UNIVERSITY OF CALIFORNIA
SAN DIEGO
The Systematic Position of the Ilyarachnoid Eurycopidae
(Crustacea, Isopoda, Asellota)
A dissertation submitted in partial satisfaction of the
requirements for the degree Doctor of Philosophy
in Marine Biology
by
George D.F. Wilson
Committee in charge:
Professor Robert R. Hessler, Chairman
Professor William A. Newman
Professor Richard H. Rosenblatt
Researcher William R. Riedel
Professor Dan L. Lindsley
1985 .
The dissertation of George D. F. Wilson is approved,
and it is acceptable in quality and form for
publication on microfilm:
ｾｈＮ＠
ｾｦＨＮ＠
Chairman
University of California, San Diego
1985
iii
To Kath,
Mom and Dad,
Judie and Jackie
and the Fur Babies.
iv
TABLE OF CONTENTS
Page
List or Figures •••••••.•••••••••••••••••••••••..••••.•••••••••••
ix
List of Tables •••••••••••••••••••••••••••••••••••••••••••••••••• xii
Acknowledgments ••••••••••••••••••••••••••••••••••••••••••••••••• xiii
Vita ••.•.. ｾ＠ ...•••••••...•.••....••....•.•..........•..•... ..•... xvii
Abstract •••••••••••••••••••••••••••••••••••••••••••••••••••••••• xxi
1. An Introduotion to deep-sea isopods and the systematio
problems in the olassifioation of the ilyaraohnoid
Euryoopidae (Crustaoea, Isopoda, Asellota) •••••••••••••••••••• 1
1.1. Introduction •••••••••••••••••••••••••••••••••••••••••••••••• 1
1.2. The munnopsoid families and the ilyaraohnoid Euryoopidae •• 11
1 •.3. Synopsis of the thesis •••••••••••••••••••••••••••••••••••• 2.3
2. The taxonomy of the ilyaraohnoid Euryoopidae
................. 27
2.1. Introduction •••••••••••••••••••••••••••••••••••••••••••••• 27
2.2. Materials and methods •••••••••••••••••••••••••••••••••••••
2.2.1. Souroes of speoimens •••••••••••••••••••••••••••••••••••
2.2.2. Reporting and use of ratios ••••••••••••••••••••••••••••
2.2 •.3. Definition of taxa and morphologioal terms •••••••••••••
2.2.4. Preparation and illustration of speoimens ••••••••••••••
27
27
.32
.3.3
.35
2.3. Taxonomy •••••••••••••••••••• ｾ＠ ••••••••••••••••••••••••••••• 37
2.3.1. Coperonus new genus ••••••••••••••••••••••••••••••••••• 37
2 •.3.2. Coperonus oomptus new speoies ••••••••••••••••••••••••• 42
2 •.3 •.3. Coperonus nordenstami new speoies ••••••••••••••••••••• 54
2 •.3.4. Hapsidohedra new genus •••••••••••••••••••••••••••••••• 55
2 •.3.5. Hapsidohedra oohlera new speoies •••••••••••••••••••••• 61
2 •.3.6. Hapsidohedra aspidophora (Wolff, 1962) •••••••••••••••• 74
2 •.3.7. Lioneotes new genus ••••••••••••••••••••••••••••••••••• 78
2 •.3.8. Lioneotes humioephalotus new speoies •••••••••••••••••• 84
2 •.3.9. Li omera Tattersall, 1905a •••••••••••••••••••••••••••• 95
2 •.3.10. 1. Lipomera) new subgenus ••••••••••••••••••••••••••• 101
2 •.3.11. L. (Lipomera) lamellata Tattersall, 1905a ............ 101
2 •.3.12. ｾＮ＠
(Paralipomera) new subgenus ••••••••••••••••••••••• 10.3
2 •.3.1.3. L. (Parali omera) knorrae new speoies •••••••••••••••• 10.3
2 •.3.14. ｾＮ＠
(Tetraoope new subgenus •••••••••.••••••••••••••••• 117
2 •.3.15. 1. (Tetraoope) ourvintestinata new speoies ••••••••••• 117
2 •.3.16. Mimooopelates new genus •••••••••••••••••••••••••••••• 1.34
2 •.3.17 Mimooopelates longipes new speoies ••••••••••••••••••• 1.39
2 •.3.18. Mimooopelates anohibraziliensis new speoies •••••••••• 154
v
TABLE OF CONTENTS, continued
Page
3. Amuletta, a new genus for Ilyarachna abyssorum Richardson
(Isopoda, Asellota, Eurycopidae) •••••••••••••••••••••••••••• 166
3.1. Abstract ••••••••••••••••••••••••••••.••••••••••••••.••••• 166
3.2. Introduction ••••••••••••••••••••••••••••••••••••••••••••• 167
3.3. Materials and Methods •••••••••••••••••••••••••••••••••••• 168
3.4. The systematic position of Ilyarachna abyssorum •••••••••• 169
....................................... 178
3.6. Amuletta abyssorum (Richardson) .......................... 180
3.5. Amuletta new genus
3.7. Acltnowledgments .••..••••.•.••..•..•.•......•...•......•... 190
4.
An outgroup for the munnopsoid families: phylogenetic
analyses of the suborder Asellota and the
superfamily Janiroidea •••••••••••••••••••••••••••••••••••••• 191
4.1. Introduction ••••••••••••••••••••••••••••••••••••••••••••• 191
4.2. Materials and Methods ••••••••••••••••••••••••••••••••••.• 192
4.2.1. Specimens •••••••••••••••••••••••••••••••••••••.••••••• 192
4.2.2. Data on janiroidean character states •••••••••••••••••• 194
4.2.3. Phylogenetic techniques ••••••••••••••••••••••••••••••• 195
4.3. A redescription of Pseudojanira stenetrioides Barnard ••••
4.3.1. Introduction
4.3.2. Pseudojaniridae new family ••••••••••••••••••••••••••••
4.3.3. Pseudojanira stenetrioides Barnard, 1925 ••••••••••• : ••
4.3.4. Discussion ••••••••••••••••••••••••••••••••••.•••••••••
.......................................... 200
200
203
204
209
4.4. The female reproductive apparatus of the Asellota •••••••• 212
4.4.1. Introduction •••••••.•••••••••••••••••••••••••••••.••.• 212
4.4.2. A survey of the female reproductive apparatus ••••••••• 217
4.4.3. Character states of the cuticular organ ••••••••••••••• 232
4.5. Character analysis of the asellotan superfamilies ••••••••
4.5.1. Introduction ••••••••••••••••••••••••••••••••••••••••••
4.5.2. Superfamily classification and taxa used ••••••••••••••
4.5.3. The characters and their states •••••••••••••••••••••••
4.5.4. Results of the character analysis •••••••••••••••••••••
vi
237
237
238
238
254
TABLE OF CONTENTS, continued
Page
4.6. A preliminary phylogenetic analysis of the Asellota ••••••
4.6.1. Previous phylogenies
4.6.2. Results of the phylogenetic analysis ••••••••••••••••••
4.6.3. Discussion ........................................... .
4.6.4. Implications for the classification of the Asellota •••
4.6.5. Evolution of Reproductive Structures ••••••••••••••••••
..................................
258
258
258
263
268
269
4.7. Phylogenetic analysis of the Janiroidea ••••••••••••••••••
4.7.1. Introduction •.•••••••••••.••••••••.•••.•••.•••••••••••
4.7.2. Taxa used ••••••••••••••.•••••••••••.••.••••••••••.•••.
4.7.3. Choice and scoring of characters ••••••••••••••••••••••
4.7.4. Character analysis ••••••••••••..••••.••••••••••••.•••.
4.7.5. The results of the character analysis •••••••••••••••••
4.7.6. The phylogenetic analysis
271
271
271
275
279
293
298
4.7.7. Discussion ........................................... . 304
.............................
5. A proposed phylogeny and classification of the munnopsoid
taxa with special reference to the ilyarachnoid Eurycopidae • 306
5.1. Introduction
5.2. Taxa Used
306
................................................ 307
5.3. Methods •••••••••••••••••••••• ｾ＠ ••••••••••••••••••••••••• •• 308
5.4. Character analysis of the munnopsoid taxa ••••••••••••••••
5.4.1. Fusion of the natasomal segments •••••••••••••••••••••
5·4.2. Comparative sizes of the natasomal pereonites ••••••••
5.4.3. Midgut •.•.•••.•••••..•......••..........•....••......
5·4·4. Clypeus
5.4.5. Rostrum ••••••••••••••••••••••••••••••••••••••••••••••
5.4.6. Frontal arch •••••••.•••••••••••.•••••••.•.••••••.•.••
5·4.7. Mandible
5.4.8. Ambulatory pereopods
5.4.9. Natatory pereopods V-VII .•..•....••••.....••.........
5·4.10. Cleft in the tip of female pleopod II ...•.•....•.....
5.4.11. Pleopods III-IV .•...••........••..•••..••..•..•.•.•..
5·4·12. Uropods
5·4.13. Results of the character analysis
............................................. .
............................................
.
.................................
..............................................
310
311
312
313
316
316
317
318
319
320
323
324
325
327
5.5. Results of the phylogenetic analysis ••••••••••••••••••••• 332
5.5.1. The estimated phylogeny ••••••••••••.••••••••••.••.•••. 332
5.5.2. Discussion and proposals for a revised classification. 335
5.6. Conclusions •........•.......•.......•.................... 341
vii
TABLE OF CONTENTS, continued
Page
Literature Cited ••••••••••••••••••••••••••••••••••••••••••••••• 343
Appendix 1: A glossary of morphological terms •••••••••••••••••• 353
Appendix 2: Output of the Program lTERMIX for the analyses of
the Asellota and the Janiroidea •••••••••••••••••••• 370
Appendix 3:
Output of the program CLIQUE for the analyses of
the Asellota and the Janiroidea ••••••••••••••••••• 385
Appendix 4:
Output of the program ITERMIX for the analysis of
selected genera of munnopsoids showing various
tree topologies ••••••••••••••••••••••••••••••••••• 393
viii
LIST OF FIGURES
Page
Figure 1.1.
An ilyarachnoid eurycopid
2
Figure 1.2.
Numerical species richness of Isopods
4
Figure 1.3.
Morphological variety of deep-sea Janiroidea
7
Figure 1.4.
The morphology of a typical munnopsoid
12
Figure 1.5.
Morphological diversity in the munnopsoids
14
Figure 1.6.
The appearance of the Ilyaracbnidae
17
Figure 1.7.
Examples of ilyarachnoid Eurycopidae
21
Figure 2.1.
Coperonus comptus new genus, new species
40
Figure 2.2.
Coperonus comptus new genus, new species
45
Figure 2.3.
Coperonus comptus new genus, new species
49
Figure 2.4.
Coperonus comptus new genus, new species
52
Figure 2.5.
Hapsidohedra ochlera new genus, new species
60
Figure 2.6.
Hapsidohedra ochlera new genus, new species
63
Figure 2.7.
Hapsidohedra ochlera new genus, new species
66
Figure 2.8.
Hapsidohedra ochlera new genus, new species
69
Figure 2.9.
Hapsidohedra ochlera new genus, new species
72
Figure 2.10.
Hapsidohedra aspidophora (Wolff, 1962)
75
Figure 2.11.
Lionectes humicephalotus new genus, new species
83
Figure 2.12.
Lionectes humicephalotus new genus, new species
86
Figure 2.13.
Lionectes humicephalotus new genus, new species
90
Figure 2.14.
Lionectes humicephalotus new genus, new species
93
Figure 2.15.
Lipomera (Lipomera) lamellata Tattersall, 1905a
100
Figure 2.16.
Lipomera (Paralipomera) knorrae new species
105
ix
LIST OF FIGURES, continued
Page
Figure 2.17.
Lipomera (Paralipomera) knorrae new species
108
Figure 2.18.
Lipomera (Paralipomera) knorrae new species
111
Figure 2.19.
Lipomera (Paralipomera) knorrae new species
115
Figure 2.20.
Lipomera (Tetracope) curvintestinata new species
119
Figure 2.21.
Lipomera (Tetracope) curvintestinata new species
121
Figure 2.22.
Lipomera (Tetracope) curvintestinata new species
125
Figure 2.23.
Lipomera (Tetracope) curvintestinata new species
128
Figure 2.24.
Lipomera (Tetracope) curvintestinata new species
131
Figure 2.25.
Mimocopelates longipes new genus, new species
138
Figure 2.26.
Mimocopelates longipes new genus, new species
142
Figure 2.27.
Mimocopelates longipes new genus, new species
145
Figure 2.28.
Mimocopelates longipes new genus, new species
148
Figure 2.29.
Mimocopelates longipes new genus, new species
151
Figure 2.30.
Mimocopelates anchibraziliensis new species
156
Figure 2.31.
Mimocopelates anchibraziliensis new species
159
Figure 2.32.
Mimocopelates anchibraziliensis new species
163
Figure 3.1.
Amuletta abyssorum (Richardson, 1911)
173
Figure 3.2.
Amuletta abzssorum (Richardson, 1911)
175
Figure 3.3.
Amuletta abzssorum (Richardson, 1911)
184
Figure 3.4.
Amuletta abzssorum (Richardson, 1911)
187
Figure 4.1.
Pseudojanira stenetrioides Barnard, 1925
202
Figure 4.2.
Pseudojanira stenetrioides Barnard, 1925
208
Figure 4.3.
Previous concepts of female reproductive organs
214
x
LIST OF FIGURES, continued
Page
Figure 4.4.
Female reproductive system of Asellus
219
Figure 4.5.
Female reproductive system of Stenetrium
222
Figure 4.6.
Female reproductive system of Pseudojanira
225
Figure 4.7.
Female reproductive system of Munna
228
Figure 4.8.
Female reproductive system of Notasellus
231
Figure 4.9.
Mating in the Asellota
236
Figure 4.10.
Male copulatory organs in Asellus and Stenetrium
241
Figure 4.11.
Male copulatory organs in several Janiroidea
244
Figure 4.12.
Comparison of asellotan first pereopods.
252
Figure 4.13.
Previous phylogenies for the Asellota
260
Figure 4.14.
Phylogeny of the Asellota proposed by W!gele
262
Figure 4.15.
A new phylogeny for the Asellota
265
Figure 4.16.
A comparison of the dactylar claws
284
Figure .4.17.
A comparison of asellotan third pleopods
287
Figure 4.18.
A comparison of higher janiroidean third pleopods
291
Figure 4.19.
Preliminary phylogenetic tree for the Janiroidea
300
Figure 5.1.
Cephalons of an acanthaspidiid and munnopsoids
315
Figure 5.2.
Estimated phylogeny of selected munnopsoid genera
334
Figure 5.3.
Estimated phylogeny of the Lipomerinae
337
xi
LIST OF TABLES
Page
Table 1.1.
The current classification of the munnopsoids
10
Table 1.2.
Diagnostic characters of the Ilyarachnidae
18
Table 2.1.
Abbreviations used in text
28
Table 2.2.
Locality Data
30
Table 2.3.
Locality Data, Woods Hole Oceanogr. Inst. samples
31
Table 4.1.
Asellota: presence and position of cuticular organ
216
Table 4.2.
Taxon-character matrix for the Asellota
257
Table 4.3.
Families used for janiroidean phylogenetic analysis
273
Table 4.4.
Taxon-character matrix for janiroidean analysis
296
Table 4.5.
Actual data for janiroidean phylogenetic analysis
297
Table 5.1.
Taxon-character matrix for munnopsoid analysis
330
Table 5.2.
Actual data for munnopsoid phylogenetic analysis
331
Table 5.3.
A revised classification of the munnopsoids
338
xii
ACKNOWLEDGMENTS
Many people have been influential in this thesis.
If I mentioned
everyone with whom I have worked over the years, this section would
look like the Scripps Institution of Oceanography telephone book.
If
you don't see your name here, please know that I am grateful for your
contribution nevertheless.
During my tenure at Scripps, Dr. Robert R. Hessler has provided
guidance and advice, instruction in oceanographic and systematic
knowledge, employment on many of his projects, and friendship.
grateful to him for these and many other things.
I am
His influence on my
career is immeasurable.
The other members of my committee provided guidance,
encouragement, and editorial work on the thesis.
They are Dr. William
A. Newman, Dr. Richard H. Rosenblatt, Dr. Hans R. Thierstein, Dr.
William R. Riedel, and Dr. Dan L. Lindsley.
gentlemen for their help and interest.
I sincerely thank these
My research also benefited
from discussions with or reviews of papers by Drs. Abraham Fleminger,
Jean Snider, Leslie Snider, Richard Brusca (Los Angeles County
Museum), David Thistle (Florida State University), and Thomas Bowman
(U.S. National Museum of Natural History).
xiii
Chapter 3 was written with Dr. David Thistle, Florida State
University.
He initially began the research reported there as part of
his work with Dr. Robert R. Hessler on a revision of the family
Ilyarachnidae.
I used the information he collected on the type
specimen from France of Ilyarachna abyssorum as a starting point for
what I wrote in chapter 3.
A systematist is severely handicapped with limited collections
of specimens to study.
Much of the information in this thesis would
be impossible without the thousands of deep-sea isopods amassed in
Dr. Hessler's laboratory from Woods Hole Oceanographic Institution
expeditions in the Atlantic.
These these samples were collected by
Dr. Howard Sanders, Dr. Hessler, and more recently Dr. J. Frederick
Grassle.
Other sources for the specimens are listed in chapter 2.
The study of deep-sea isopods is what it is today because of an
important monograph on the Asellota by Dr. Torben Wolff, Zoological
Museum of the University of Copenhagen_
In bringing together all the
literature on these isopods, organizing it into a workable scheme, and
setting an example for the necessary quality of work, he has made a
lasting impact on all later work.
Robert Hessler extended this
tradition by writing a valuable monograph on the Desmosomatidae of the
Gay Head-Bermuda Transect.
xiv
My initial interest in evolutionary questions derives from my
undergraduate work with Dr. Craig E. Nelson, Zoology Department,
Indiana University.
His enthusiasm for research in vertebrate
speciation and biogeography was infectious, and has influenced the
direction of my thinking.
I thank him for this and for his good humor
during my undergraduate fumblings with him.
The data was analysed, and this thesis was written entirely on a
microcomputer, a fact made possible by the recent revolution in
personal computer hardware and software.
My work would have been much
more difficult and time consuming without such software packages as
"WordStar" by MicroPro Corp., "123" by Lotus Corp., "dBase III" by
Ashton-Tate, and "SideKick" and "Turbo Pascal" by Borland
International.
In addition to these commercial software packages,
"PHILIP", the phylogeny inference programs supplied by Dr. Joseph
Felsenstein, University of Washington, made the phylogenetic analyses
much easier, more objective, and reproducible.
The research in this thesis was supported by primarily by a
National Science Foundation, Systematic Biology grant to myself and
Dr. Robert R. Hessler.
Additional funding sources, including funds to
purchase a microcomputer system, were provided by a National Oceanic
and Atmospheric Administration, Marine Mineral Management Service
contract to Dr. Fred N. Spiess and Dr. Robert R. Hessler, and by a
NOAA subcontract from Oregon State University, coordinated by Dr. Gary
Taghon, OSU.
xv
I would like to thank the members of Dr. Hessler's lab, past and
present, for their help.
Deserving special mention are Bryan Burnett
who showed me how to ink my pencil illustrations, and Elana Varnum who
helped me with the NOAA sponsored research and organized many details.
Finally, I would like to recognize the members of my family.
Martha K. Fries-Wilson provided the domestic support, encouragement,
advice, readings of various papers, and love that made this thesis
possible.
My parents, George A. Wilson and Violet L. Shinlever
Wilson, provided my start in life and my interest in living things,
as well love and encouragement while this work was in progress.
sisters, Jacqueline L. Wallace and Judith L. Noelker, and their
families were good friends and cheerleaders.
I give my love and
sincere thanks to you all.
xvi
Ｍｾ
My
VITA
GEORGE D.F. WILSON
1967-1968
Laboratory Assistant, Herpetology, Zoology Department,
Indiana University, Bloomington.
1968-1969
Laboratory Assistant, Plant Physiology, Botany Department,
Indiana University, Bloomington.
1969
BA, Indiana University.
1969-1972
Graduate Research Assistant, Deep-sea Isopod Taxonomy,
Marine Biological Research Divison, Scripps Institution
of Oceanography.
1972
MS, Scripps Institution of Oceanography, University of
California, San Diego.
1973-1981
Staff Research Associate, Marine Biological Reasearch
Divison, Scripps Institution of Oceanography.
1981-1985
Associate Specialist, Marine Biological Reasearch Divison,
Scripps Institution of Oceanography.
1985
Doctor of Philosophy, Scripps Institution of Oceanography,
University of California, San Diego.
PUBLICATIONS
Wilson G., Hessler R.R. 1974. Some unusual Paraselloidea (Isopoda,
Asellota) from the deep benthos of the Atlantic. Crustaceana,
27(1 ):47-67.
Thiel H., Thistle D., Wilson G. 1975. Ultrasonic treatment of
sediment samples for more efficient sorting of meiofauna.
Limnology and Oceanography 20(3):472-473.
Wilson G. 1976. The systematics and evolution of Haplomunna and its
relatives (Isopoda, Haplomunnidae, n.fam.). Journal of Natural
History, 10:569-580.
xvii
Wilson G., Thistle D., Hessler R. 1976. The Plakarthriidae (Isopoda;
Flabellifera): deja VUe Zoological Journal of the Linnean
Society, 58(4):331-343.
Hessler R.R., Wilson G., Thistle D. 1979. The deep-sea isopods: a
biogeographic and phylogenetic overview. Sarsia, 64(1-2):67-76.
Wilson G. 1980. Superfamilies of the Asellota (Isopoda) and the
systematic position of Stenetrium weddellense (Shultz).
Crustaceana, 38(2):219-221.
Wilson G. 1980. New insights into the colonization of the deep sea:
Systematics and zoogeography of the Munnidae and the
Pleurogoniidae comb. nov. (Isopoda; Janiroidea). Journal of
Natural History, 14(2):215-236.
Wilson G., Hessler R.R. 1980. Taxonomic characters in the morphology
of the genus ｅｵｲｙｃｏｾ･＠
(Crustacea, Isopoda) with a redescription of
!. cornuta Sars, 18 4. Cahiers de Biologie Marine, 21:241-263.
Wilson G. 1980. Incipient speciation in a deep-sea eurycopid isopod
(Crustacea). American Zoologist 20(4):815 (Abstract).
Iverson E.W., Wilson G. 1981. Paramunna guadratifrons, new species,
the first record of the genus in the North Pacific Ocean
(Crustacea: Isopoda: Pleurogoniidae). Proceedings of the
Biological Society of Washington, 93(4):982-988.
Wilson G. 1981. Taxonomy and postmarsupial development .of a dominant
deep-sea eurycopid isopod (Crustacea). Proceedings of the
Biological Society of Washington, 94(1):276-294.
Wilson G., Hessler R.R. 1981. A revision of the genus Eurycope
(Isopoda, Asellota) with descriptions of three new genera. Journal
of Crustacean Biology, 1(3):401-423.
Wilson G. 1982. Two new natatory asellote isopods (Crustacea) from
the San Juan Archipelago, Baeonectes improvisus n.gen., n.sp. and
Acanthamunnopsis miller n.sp., with a revised description of ｾ＠
hystrix Schultz. Canadian Journal of Zoology 60(12):3332-3343.
Wilson G. 1983. Variation in the deep-sea isopod, Eurycope iphthima
(Asellota, Eurycopidae): Depth related clines in rostral
morphology and in population structure. Journal of Crustacean
Biology, 3:127-140.
Wilson G. 1983. An unusual species complex in the genus Eurycope
(Crustacea: Isopoda: Asellota) from the deep North Atlantic Ocean.
Proceedings of the Biological Society of Washington 96(3):452-467.
xviii
Hessler R.R., Wilson G. 1983. The ｯｲｾｧｮ＠
and biogeography of
malacostracan crustaceans in the deep sea. In: "Evolution, Time,
and Space: The Emergence of the Biosphere," edited by R.W. Sims,
J.H. Price, and P.E.S. Whalley, Systematics Association, Special
Publication, 23:227-254.
Wilson G. 1983. Dispersal and speciation in the deep-sea janiroidean
isopods (Asellota, Crustacea). American Zoologist 23(4):921
(Abstract).
Wilson G. 1983. Systematics of a species complex in the deep-sea
genus Eurycope, with a revision of six previously described
species (Crustacea, Isopoda, Eurycopidae). Bulletin of the
Scripps Institution of Oceanography 25:1-64.
Wilson G. 1984. The evolution of the janiroidean female reproductive
apparatus (Crustacea, Isopoda, Asellota). American Zoologist
24(4):67A (Abstract).
Wilson G., Thistle D. 1985. Amuletta, a new genus for Ilyarachna
abyssorum Richardson, 1911 (Isopoda: Asellota: Eurycopidae).
Journal of Crustacean Biology 5(2):350-360.
Wilson G., Hessler R. In Press. Speciation in the Deep Sea.
Review of Ecology and Systematics.
xix
Annual
FIELDS OF STUDY
Maj or
Field: Marine Biology
Studies in Deep-Sea Biology.
Professor Robert R. Hessler
Studies in Crustacean Biology.
Professors Robert R. Hessler and William A. Newman
Studies in Invertebrate Zoology
Professors Edward Brinton, Abraham Fleminger,
and Nicolas D. Holland
Studies in Ichthyology
Professor Richard H. Rosenblatt
Studies in the Philosophy of Science
Professors Paul K. Dayton and George N. Somero
Studies in Biological Oceanography
Professors John A. McGowan, Michael M. Mullin,
and John D. Strickland
Studies in Ecology and Statistics
Professor Edward W. Fager
Studies in Marine Chemistry
Professor Edward D. Goldberg
Studies in Marine Geology
Professor H. William Menard
Studies in Physical Oceanography
Professors Myrl C. Hendershott and Joseph L. Reid
ＭｾＢＧ
xx
ABSTRACT OF THE DISSERTATION
The Systematic Position of the Ilyarachnoid Eurycopidae
(Crustacea, Isopoda, Asellota)
by
George D.F. Wilson
Doctor of Philosophy in Marine Biology
University of California, San Diego, 1985
Professor Robert R. Hessler, Chairman
Although isopod crustaceans of the suborder Asellota are a
dominant part of the deep-sea benthic macrofauna, the systematic
relationships between the major families are poorly understood.
The
fully natatory families, Munnopsidae, Eurycopidae, and Ilyarachnidae,
are in the greatest need of study.
Within this munnopsoid group, the
ilyarachnoid Eurycopidae, a poorly described assemblage of genera,
confound the definitions between the Ilyarachnidae and the
Eurycopidae.
This thesis determines how the llyarachnoid eurycopids
are related to the other taxa, and shows whether they are a
monophyletic group or only a polyphyletic assemblage.
In the descriptive section, the ilyarachnoid Eurycopidae are
found to include 5 genera, 4 of which are new.
The definition of the
Ilyarachnidae is improved by the removal of the species Ilyarachna
abyssorum to the eurycopid genus Amuletta, and weaknesses in the
classification of the munnopsoid families are discussed.
xxi
The superfamilies of the Asellota are phylogenetically analysed
to find appropriate outgroups for the superfamily Janiroidea, which
includes the munnopsoids.
Pseudojanira stenetrioides is redescribed
because it is related to the janiroideans, but distinct from this and
other superfamilies.
The relationships of the superfamilies of the
Asellota are illuminated by a morphological study of a female
copulatory structure called the cuticular organ.
These morphological
data are combined with other characters to derive a well resolved
phylogeny of the asellotan superfamilies.
The outgroup for the
munnopsoids is found by analyzing the Janiroidea for characters in the
morphology of the dactylar claws, the third pleopods, and other little
used aspects of the janiroidean form.
The phylogenetic estimates
derived from all these characters nominate the Acanthaspidiidae as the
best candidate for an outgroup to the munnopsoids.
Character analyses of selected munnopsoid genera is made possible
by comparison with character states in the Acanthaspidiidae.
The
resulting character-taxon matrix produces phylogenetic estimates that
are not fully resolved, but have a generally consistent form.
Because
the current classification of the families is not reflected in the
phylogeny, a proposal is made to place all the munnopsoids into one
family, the Munnopsidae.
The ilyarachnoid Eurycopidae are a
monophyletic group and are assigned to the subfamily Lipomerinae.
xxii
CHAPTER 1
AN INTRODUCTION TO DEEP-SEA ISOPODS AND THE SYSTEMATIC PROBLEMS
IN THE CLASSIFICATION OF THE ILYARACHNOID EURYCOPIDAE
(CRUSTACEA, ISOPODA, ASELLOTA)
INTRODUCTION,
Isopod crustaceans that live in such accessible environments as a
backyard or any shallow marine habitat are cryptic animals.
To find
isopods, often one must look in hidden habitats, such as under a rock,
in cracks and crevices, or buried in the gills of a fish.
environment, isopods live in the open.
But in one
This is in the deep sea, on
the sea floor and water column below the photic zone, the most
extensive environment on our planet (Sverdrup et al, 1942).
Unlike anywhere else, isopods of the deep-sea benthos are a major
feature of the biota.
In most deep-sea benthic samples isopods are
among the most abundant crustacean taxa, and often account for a large
fraction of the species present in an area (Sanders and Hessler, 1967;
Wilson and Hessler, unpublished manuscript; Wilson, in progress).
For
example, in the equatorial Pacific manganese nodule province, isopods
represent the third most abundant macro benthic taxon and their
diversity possibly exceeds 85 species (fig. 1.2).
1
In one program
2
Figure
ＱｾＮ＠
An example of an ilyarachnoid eurycopid (Crustacea,
Isopoda, Asellota), in lateral view.
3
Figure 1.2.
The numerical species richness of two localities in the
Equatorial Pacific Ocean.
The expected number of species curves for
the lumped data of each locality were calculated using the Hurlbert
(1971) rarefaction technique.
The straight line intersecting the
origin traces the maximum of one species per individual.
were collected with 0.25 2 box corers.
Environmental Survey) site A samples (N
90 30' N, 151 0 30' W, 5100-5200 m.
The samples
The DOMES (Deep Ocean Mining
= 50)
are from approximately
The samples (N
= 15)
from the
Scripps Institution of Oceanography cruise ECHO leg I (DOMES site C)
are from approximately 140 40' N, 125 0 25' W, 4500 m.
are predominantly manganese nodules bottoms.
The two sites
4
ＱＮｾＭ＠
ISOPODA
N1UD81'ical Species licJmess
5
where 15 quantitative samples were collected from a 4500 m deep
manganese nodule bottom, 154 specimens of isopods were counted (Wilson
and Hessler, unpublished manuscript).
These specimens comprised 59
separate species, a high species richness considering that only 3.75
m2 of the sea floor was sampled (Wilson, in progress).
Deep-sea isopods do not resemble their cryptic shallow marine,
fresh water, and terrestrial counterparts.
The archetypical isopod is
dorsoventrally flattened and has 7 pairs of similar legs, hence the
translation of their name "like footed."
This body form is
undoubtedly related to their cryptic life style of creeping underneath
objects and in cracks and crevices.
Deep-sea isopods, however,
display a great variety of forms, from narrow walking-stick creatures
to things that look like little space ships and highly modified
swimmers.
Their body forms are evidence for a great evolutionary
radiation, one apparently in full flower.
A few examples of these
unusual animals are shown in figure 1.3.
These morphological differences reflect evolutionary paths
separate from those of other Isopoda: the best evidence collected to
date indicates most of the families of deep-sea isopods evolved there,
and not in shallow water (Hessler and Thistle, 1975; Hessler, Wilson,
and Thistle, 1979).
The evolution of entire families in the deep-sea
also has biogeographic consequences.
These families and most of their
6
Figure 1.3.
A few examples of the morphological variety of Isopoda
Asellota, superfamily Janiroidea, from the deep sea.
Notice that most
of the genera represented here lack eyes, practically a diagnostic
characteristic of deep-sea isopods.
Dorsal views, not to same scale,
although most specimens shown are approximately 1-3 mm long.
Ilyarachna, Ilyarachnidae.
Eurycopinae.
a,
A,
B, Syneurycope, Eurycopidae, subfamily
Disconectes, Eurycopidae, subfamily Eurycopinae.
Mesosignum, Mesosignidae.
Notoxenoides, Paramunnidae.
E, Exiliniscus, Nannoniscidae.
G, Momedossa, Desmosomatidae.
Aspidoniscus, Haploniscidae •. I, Munna, Munnidae.
family incertae sedis.
H,
J, Austrofilius,
K, Abyssianira, Abyssianiridae.
Macrostylis, Macrostylidae.
F,
L,
M, Haplomesus, Ischnomesidae.
D,
7
o
d
L
8
genera are cosmopolitan in the deep-sea, but are found in shallow
water only where special conditions permit their existence (e.g., high
latitudes: Hessler and Wilson, 1983).
In spite of their ubiquity in
the deep-sea, evidence from some groups suggests that the evolution of
new species is actively occurring (Wilson, 1980a, 1983a), and species
)
ranges are small geographic areas and narrow depth ranges (Wilson,
1983b, 1983c).
Although deep-sea isopods are ecologically important and
biogeographically interesting, systematic knowledge on the most
important families is limited.
The primary deep-sea families belong
to the suborder Asellota, the systematics of which can best be
described as unstable.
The Asellota has been the subject of several
major monographs and numerous smaller papers (best reviewed before
1960 by Wolff, 1962).
In the last three decades great interest in the
taxon has been generated by the discovery of its high diversity of
both species and morphological types in the deep-sea (Menzies, 1962;
Wolff, 1962; Birstein, 1963;
Hessler and Sanders, 1967; Hessler,
1970; Hessler, Wilson, and Thistle, 1979).
This interest has resulted
in the rapid accumulation of new species and genera, described from
deep-sea samples taken since the early 60's.
In spite of this new
information, no major reorganization of the suprageneric taxa has been
attempted since the landmark papers of Wolff (1962) and Menzies
(1962).
As a result, the family-level groups have become poorly
defined as they have been forced to include a broad variety of taxa.
9
This problem is most acute in a group of families called the
munnopsoids: Munnopsidae, Eurycopidae, and Ilyarachnidae.
Taxa have
been described that appear to be intermediate between the Eurycopidae
and the Ilyarachnidae (the genus Betamorpha Hessler and Thistle,
1975), and a group of eurycopids has been discovered that are very
similar to the Ilyarachnidae but cannot be placed there owing to the
current definitions of the families (Wilson and Hessler, 1981).
ilyarachnoid Eurycopidae are the subject of this thesis.
present a solution to the systematic problem they present.
These
In it, I
In so
doing, some light will be shed on the evolutionary paths taken by the
deep-sea asellote isopods and their ancestors.
10
Table 1.1.
The current classification, of the munnopsoids (family
Munnopsidae sensu
ｾ＠
of Sars, 1883, temporary group Incertae sedis).
(extracted from: Bowman and Abele, 1982; Hessler and Thistle, 1975;
and Wilson and Hessler, 1981).
Only the genus-level taxa discussed in
the text are shown.
Crustacea
Class Malacostraca
Subclass Eumalacostraca
Superorder Peracarida
Order Isopoda
Suborder Asellota
Superfamily Janiroidea
Family Munnopsidae sensu stricto
Genus Paramunnopsis Hansen,1916
Family Eurycopidae
Subfamily Eurycopinae
Genus Eurycope Sars, 1864
Genus Betamorpha Hessler and Thistle, 1975
Subfamily Acanthocopinae
Subfamily Bathyopsurinae
Subfamily Syneurycopinae
Family Ilyarachnidae
Genus Ilyarachna Sars, 1864
IlfaraChna abyssorum Richardson, 1911
temporary genus incertae sedis)
Ilyarachnoid Eurycopids, temporary group incertae sedis
Genus Lipomera Tattersall, 1905a
(Taxa misplaced in the literature)
Ilzarachna aspidophora Wolff, 1962
Eurycope frigida Vanh6ffen, 1914
frigida Nordenstam, 1933
Eurycope ｾ＠
11
THE MUNNOPSOID FAMILIES AND THE ILYARACHNOID EURYCOPIDAE
The munnopsoid families of the isopod suborder Asellota are often
a dominant fraction of deep-sea sled and dredge samples, and are
represented by many species and genera in single samples (Wilson and
Hessler, 1980, 1981).
Figure 1.4 illustrates the morphology of a
common munnopsoid isopod.
The success of the munnopsoids may be
related to their primary specialization, the swimming habit.
Although
primitive asellote isopods have lost the ancient crustacean ability to
swim, the Munnopsoids have an integrated set of adaptations that allow
them to swim rapidly and efficiently, but in a posterior direction.
This ability has resulted in an important adaptive radiation, with the
evolution of numerous offshoots from the basic swimming type
exemplified by the genus Eurycope (fig. 1.5).
The munnopsoids, a large family as originally conceived by G.O.
Sars (1883, 1899), are now classified into three separate families
(see table 1.1): the Eurycopidae with several subfamilies, the
Ilyarachnidae, and the Munnopsidae.
The munnopsids have taken the
swimming life to its logical extreme: some of its members are
holopelagic.
Ilyarachnids, on the other hand, have gone to the
opposite extreme by specializing in burrowing into the sediment
surface with paddle-shaped posterior legs (probably the source of
Sars' appellation of "mud spider" for the type-genus of this group).
Nevertheless, ilyarachnids retain the ability to swim.
12
nat
Figure 1.4.
The morphology of a typical munnopsoid, Eurycope iphthima
. Wilson (1981), in lateral view with anterior to the left.
The main
body parts are the cephalon (c), the ambulosome (amb) which is made of
pereonites (segments of the thorax bearing legs) 1-4 (numbered in the
figure), and the natasome which is made of pereonites 5-7 (numbered in
the figure) and the pleotelson (pI).
The limbs from anterior to
posterior are: the antennula (AI), the antenna (All), the mouth parts
(mp) with only the mandible and maxilliped externally visible, the
ambulatory pereopods (PI-IV), the natatory pereopods or natapods
(PV-VII), and the uropod (ur).
The limbs of the pleotelson, the
pleopods, are obscured in this view by the natapods.
13
Figure 1.5.
A sampling of the morphological diversity present in the
munnopsoids, those Isopoda Asellota with distinct natasomes.
shown in dorsal view with anterior toward the top.
Munnopsurus.
Munnopsis.
C, Acanthocope.
G, Syneurycope.
D, Storthyngura.
H, Paropsurus.
All are
A, Eurycope.
E, Ilyarachna.
B,
F,
14
•
15
As presently constituted, eurycopids are more difficult to classify
under this functional scheme because many of the groups in the family
have specializations that resemble those found in the other two
families.
Some of these similarities are true homologies, reflecting
a common ancestry, such as the resemblance of the eurycopid Betamorpha
to primitive members of the Ilyarachnidae (Thistle and Hessler, 1977).
Other similarities are undoubtedly convergences to a common body form.
Recent revisionary work (Wilson and Hessler 1980, 1981) has
identified a group of genera within the Eurycopidae that have an
"ilyarachnoid facies" (Fig. 1.6, 1.7).
A comparison of the diagnostic
characters of the Ilyarachnidae (Wolff, 1962) with the features of
these eurycopids (Table 1.2) reveals SUbstantial similarities between
the two groups.
The overall shape of the natasome and the cephalon
are most compelling.
In the current literature, these ilyarachnoid
eurycopids are only an informal collection of species and genera with
little formal systematic status.
On a purely typological basis (using
similarities only), they should be classified with the Ilyarachnidae.
The similarities, however, may be due to convergence of unrelated taxa
to a common body form, thus decreasing the naturalness and usefulness
of such a phenetic classification.
Therefore, these character
complexes should be examined in some detail.
16
Figure 1.6.
Dorsal views of several munnopsoids to illustrate the
appearance of the Ilyarachnidae.
Ilyarachna abyssorum.
A, Eurycope.
D, Lipomera.
ilyarachnoid eurycopids.
B, Ilyarachna.
E, a new genus of the
C,
17
c
18
TABLE 1.2:
A comparison of the characters from the diagnosis of the
Ilyarachnidae (Wolff, 1962) with the ilyarachnoid eurycopids.
Has similar character. "_"
=
No similar character.
"+" =
Characters found
in all the munnopsoids omitted.
Ilyarachnoid
Eurycopids
Character from the diagnosis
of the Ilyarachnidae
Pleotelson subtriangular
+
Head broad, without frontal area
+
Antennulae terminal or subterminal
+
Mandibles short and thick
+, -
Mandibles with obtuse incisive part
+, -
Mandibles with reduced setiferous molar process
Pereopods III and IV with short basis
*
Uropods with flattened, oval, setiferous basal
segment and reduced rami
*
+, -
This character is considered by Thistle and Hessler (1976) to be the
principal diagnostic character separating the Ilyarachnidae from the
Eurycopidae.
19
Members of the ilyarachnoid eurycopids first appear in the
literature with a description of Lipomera lamellata Tattersall 1905a
(1905b).
Related species are Eurycope frigida Vanhoffen 1914,
frigida Nordenstam 1933, Ilyarachna aspidophora Wolff 1962.
!. cf.
Recently,
these species were recognized as an informal taxon having an
"ilyarachnoid facies" within the Eurycopidae similar to, but possibly
independent of the Ilyarachnidae (Wilson and Hessler, 1981).
In spite
of the limited treatment, species of this group appear in more than 60
samples of deep-sea isopods from the North and South Atlantic Oceans,
some samples having more than 90 specimens and two or more species.
Similar to other advanced deep-sea taxa, the ilyarachnoid eurycopids
display high latitude emergence.
A previously unknown species was
discovered in a sample collected by Robert Hessler from Norwegian
coastal waters, a region of intensive investigation over the last
century.
Thus, the ilyarachnoid eurycopids are particularly worthy of
systematic attention because they are a numerically and
biogeographically important group of genera that has received little
attention in the literature.
20
Figure 1.7.
Examples of ilyarachnoid eurycopids in lateral view,
anterior is to the right.
described in chapter 2.
A-C and E-F are examples of new genera
D is a new species of the previously
described genus Lipomera Tattersall.
for comparison.
G is a member of Ilyarachna Sars
21
22
Because the ilyarachnoid eurycopids confound the overall
distinction between the Ilyarachnidae and the Eurycopidae, a
systematic investigation of these isopods reveals much about the
evolution within the munnopsoids.
Kussakin (1973) proposed a
phylogeny for the established families of the Asellota that showed the
close relationship of the munnopsoid families, but he ommitted details
of the phylogenetic construction, preventing any analysis on the
nature of this relationship.
Little of this basic systematic work has
been attempted since.
In the following chapters, the ilyarachnoid eurycopids are
described, and then analysed using phylogenetic techniques in order to
discover their relationships to the other natatory taxa.
By analyzing
the potential links between the munnopsoid families, our knowledge of
their systematic relationships can be placed on a more solid
foundation.
23
SYNOPSIS OF THE THESIS
The primary aim of the researoh reported here will be to
determine whether the similarities between the ilyaraohnoid
Eurycopidae and the Ilyaraohnidae are synapomorphies, uniquely derived
and shared specializations, or whether they are homoplasies,
oonvergenoes that reveal little about the phylogenetio
between groups.
ｲ･ｬ｡ｾｯｮｳｨｩｰ＠
Because the Euryoopidae, as a family, is
morphologioally and potentially phylogenetioally heterogeneous, an
important question is how the ilyarachnoid euryoopids should be
olassified vis-a-vis the other munnopsoid taxa.
As the final ohapter
will show, this inquiry results in a new systematio organization for
the munnopsoids.
A related question is whether the ilyaraohnoid
eurycopids are a monophyletio group rather than a "faoies", a
polyphyletio assemblage of speoies with the same overall appearanoe.
Before these questions oan be answered, other information must be
added to the inquiry beoause the ilyaraohnoid Euryoopidae are largely
ignored or unknown in the ourrent literature.
Chapter 2 remedies this
situation with detailed desoriptions of the genera of this little
known group.
Speoial attention will be paid to the morphology
ｯｾ＠
the
natasome and oephalon in order to lay a firm foundation for the
phylogenetio analysis.
As the reader will see, four new genera are
desoribed, and Lipomera Tattersall is divided into three subgenera.
24
To understand the composition of the Ilyarachnidae, the species
Ilyarachna abyssorum Richardson must be defined carefully and its
systematic position considered.
This is the content of chapter 3, in
which this species is removed from the Ilyarachnidae, and is assigned
to a new genus, Amuletta.
Moreover, some of the difficulties with the
current classification of the munnopsoids are discussed.
A serious problem with the study of phylogenetic relationships of
the munnopsoid families is that their sister group or groups are
unknown.
In fact, as touched on above, little is known of the
relationships of all the families in the Janiroidea.
Chapter 4 delves
into these questions by taking the analysis to a higher systematic
level, the superfamilies of the isopod suborder Asellota, and then
working back to the family-level groups.
A poorly known South African isopod called Pseudojanira
stenetrioides Barnard has an important role in this study.
Although
it has previously been classified in the janiroidean family Janiridae,
a detailed study of its male and female reproductive morphology shows
that it does not belong in the superfamily Janiroidea.
In the first
section of chapter 4, Pseudojanira is redescribed as the type of a new
family of Asellota, with uncertain superfamily relationships.
As Pseudojanira shows, an understanding of reproductive
morphology is a key to understanding the relationships of the
asellotan superfamilies.
Female copulatory organs found in most
Janiroideans, called "cuticular organs" by a number of authors
(Veuille, 1978b), are shown in chapter 4 to occur in all asellotans
25
examined.
The presence of these organs does not define the
Janiroidea, but their position with respect to the female oopores does
help to delimit a major group of families within the Janiroidea.
The information on the cuticular organs is combined with a number
of other characters that help define major groups of the Asellota to
provide a new phylogeny for the entire suborder.
This analysis
reaffirms the evolutionary hypotheses presented by earlier authors and
argues against the recent concept of asellotan phylogeny presented by
ｗｾｧ･ｬ＠
(1983).
New structure is added to the evolution of the
Asellota by the recognition of Pseudojanira as the sister group to the
Janiroidea, and by the startling conclusion that the families Munnidae
and Pleurocopidae must be derived from the ancestral stock of the
Janiroidea before the Janiridae.
All this sets the stage for the goal of chapter 4, the
identification of the outgroup to the munnopsoids.
A series of little
understood characters seen in the Janiroidea are analysed in the last
section; examples of such characters are the setation and size of the
rami of the third pleopod.
These characters generate a poorly
resolved estimate of the phylogeny of the Janiroidea, although the
single result sought, the outgroup for the munnopsoids, is attained.
That group is shown to be a spiny, but otherwise little modified,
deep-sea isopod family called the Acanthaspidiidae.
26
To answer questions concerning systematic position of the
ilyarachnoid eurycopids, chapter 5 provides the results of an analysis
of a great many characters, narrowed down to a few attributes that
help to define groups within the munnopsoids.
These characters are
used in a new phylogenetic treatment of a selected subset of the
genera of all the munnopsoid families, including the taxa of the
ilyarachnoid eurycopids.
The estimated evolutionary structure of the
munnopsoids bears little resemblance to the concept of three separate
families, so they are submerged into the broader family concept of
Sars, the single family Munnopsidae for all the genera.
Chapter 5
concludes that the ilyarachnoid eurycopids are a monophyletic group,
and assigns them to the subfamily Lipomerinae.
CHAPTER 2
THE TAXONOMY OF THE ILYARACHNOID EURYCOPIDAE
INTRODUCTION
The isopods of the family Eurycopidae that have the "ilyarachnoid
facies" (Wilson and Hessler, 1981) are a fairly diverse group.
Although they have Ilyarachna-like features tying them all together,
they do not constitute a single genus-level taxon.
The members of
this group vary considerably in the development of the last thoracic
segment, and in the form of the cephalon, as well as having definable
differences in the uropods and pleotelson.
As a result, this chapter
redescribes Lipomera Tattersall, 1905a, and divides the species of
this genus into three subgenera.
Four new genera are erected to
contain the remaining bulk of the specimens originally classified as
. ilyarachnoid Eurycopidae.
MATERIALS AND METHODS
SOURCES OF SPECIMENS
The specimens used in this study came from a variety of sources,
indicated by abbreviations (meanings in table 2.1) in table 2.2 and
table 2.3.
The largest contributor to the collection of ilyarachnoid
eurycopids came from a series of deep benthic sampling transects in
various basins of the Atlantic Ocean conducted by the Woods Hole
Oceanographic Institution (WHOI) under the direction of
27
28
Table 2.1.
Abbreviations used in text.
Sources of Specimens
Abbreviation
Meaning
BAT
Battelle New England Marine Research Laboratory
BMB
Marine Biology- Course at Herdla, Norway
INCAL
Joint European Expedition "Intercalibration"
IODal
Institute of Oceanography, Dalhousie
LGL
LGL Ecological Research Associates
NZOI
New Zealand Oceanographic Institute
RANKIN
John Rankin Samples, Weddell Sea
WHOI
Woods Hole Oceanographic Institution
Depositories of Specimens
Abbreviation
Meaning
MNHNP
Museum National d'Histoire Naturelle, Paris
SIO
Robert Hessler collection,
Scripps Institution of Oceanography
USNM
United States National Museum of Natural History
ZMUC
Zoological Museum, University of Copenhagen
Other Abbreviations
Abbreviation
Meaning
bl
Body Length, measured from frons to pleotelson tip
inds
Individuals, usually reporting number used in a
measurement.
29
Howard Sanders, and, at different times, Robert Hessler or J. Fredrick
Grassle.
These samples include the Gay Head-Bermuda Transect, off New
England (Sanders et al, 1965; Hessler and Sanders, 1967).
An
important collection of Antarctic Isopoda was provided by John Rankin,
University of Connecticut, from samples collected in the Weddell Sea
during the years 1968 and 1969 (68Rankin and 69Rankin samples).
Specimens from the South Shetland Island were collected by Eric Mills,
Institute of Oceanography, University of Dalhousie, and Robert
Hessler, Scripps Institution of Oceanography, during the "Hudson 70
Expedition" to the antarctic and subantarctic islands in the vicinity
of the Palmer Penninsula (IODal samples).
Some specimens from the
Northeast Atlantic were collected by a joint European sampling program
around the British Isles and in the Bay of Biscay (INCAL samples, see
Sibuet, 1979, for more information).
Robert Hessler provided 2
samples that were collected in the Hjeltefjord during a marine biology
course at Herdla, Norway (HMB samples).
Recent studies of the slope
fauna off the Eastern United States, directed by James Blake and Nancy
Maciolek-Blake of Battelle New England Marine Research Laboratory has
provided several samples that help establish the ranges of species
found on the Gay Head-Bermuda Transect (BAT samples).
An important
collection of Gulf of Mexico Isopoda collected during 1983 and 1984
(LGL83 and LGL84 samples) was provided by Linda Pequegnat, LGL
Ecological Research Associates.
Specimens collected from slope depths
off New Zealand (NZOI samples) were kindly sent by Desmond Hurley,
30
Table 2.2. San¢es That Contained Ilyarachnoid Eurycopids. Oascriptions and abbreviations of
prograna given In text. In samples. takan with trawls, that have start and finish positions. only
the midpoints for the both latitudes. longitudes, and depths are given. AU positions are rounded
off to the nearest minute. The abbreviations for the genera are as foUClfllSI C, Coperonus n. gen.;
H, Hapsidahedra n. gen., LN, Lionactes n.
LP1, Lipqmara (L1p9mera) n. ｾＮＬ＠
LP2, Lipomera
(Paral1ppl!!1'!) n.
LP3, Lipomera (Tetrasape) n. SUbgen.; 1111, !I!1mocape1ates n. gen. lonaipas
n.ap. species group, JII2, !I!1!aoc<p!lates anch1breziliensis n. gen., n.ap. species group. Generic
abbreviations with an asterisk (*) indicate a type locality for a described or new specie••
Generic abbreviations with a double asterisk (H) indicate a type locality for the type species of
the genus. All S8IIIPles except those collected by the IdoocIs Hole Ilceanographic Institution programs.
gen.,
subgan.,
PragrM and"
N!.Inbar
Ganus
Station
C*
(Norcllinstanl, 1933)
s.edish Antarctic
Expedition sta. 311
(TattersaU, 1905)
R/V Helga stetion
LP1H
C*, LN*
C
C
C
C
C, LN
LP3
LP3
LP3
LP3
LP3
1111
1111
H
C
LN
C, LNH
L3
H
H
H
LP2
LP2
LP2
LP2
JII2
JII2
JII2
JII2
JII2
JII2
Location
l1Iidpoint
9!pth (iii)
l'Iidpoint
Latitude
I'I1dpalnt
Longitude
54° 11' S
:!B0 1S' III
281
agO 3S' E
385
650
650
South Georgia
off CulDlrland Say
Porcupine Sank
(vanh8ffen, 1914)
Gauss Station
Eastern Antarctica
68Rankln 0001 ES
S. ldeddell Sea
68Rankln 0001 AD
S. IIIaddell Sea
68Rankln 0018ES
S. IIIeddell Sea
68Rankln 0055S8T
III. IlleddeU Sea
69Rankin IJJ1 AD
S. IdeddeU Sea
BAT 1111-13-1-7
Off Delaware Bay, USA
BAT 51-3-1-3
Off Cape Lookout;, USA
BAT S2-3-2-{1-9)
Off Cape Lookout, USA
HIS Beyer 7-8/VII/18 Hjaltefjord, ｎｯｾｹ＠
HIS RPsled II/VII/18 Hjeltef jord, Norway
INCA!. 0513
r£ Atlantic Ocaan
INCA!. OSOil
r£ Atlantic Ocaan
IM:AL 111503
HE Atlantic Ocean
lOOal 6
S. Shatland Isl.
lOOal 7
S. Shetland Isl.
S. Shetland Isl.
IOOal 13
LGL83 C1/4/5-10
N. Gulf of IIIexico
LGL83 CII/3/Q-5
N. Gulf of Jllexico
LGL84 C2/2/1
N. Gulf of I'Iexico
N. Gulf of I'Iexico
LGL84 CII/8/2
N. Gulf of I'Iexico
LGL84 E4/2/1
LGLSII 1112/1 /1
N. Gulf of Jllexico
N. Gulf of JIIexico
LGL84 1113/1 /1
LGL84 1113/3/1
N. Gulf of I'Iexico
Off N8III Zealand
NZOIF719
NZOI E753
Off N.... Zealand
NZOI F911
Off N8III Zealand
NZOI P939
Off N8III Zealand
NZOI S147
Off N8III Zealand
NZOI S153
Off N8III Zealand
53°
se'
N
eao 02' S
711° 06' S
711° 06' S
72° lIS' S
66° 48' S
77° 49' 5
ｾ＠
54' N
34° 15' N
34° 15' N
SOO 311' N
SOO
46°
46°
48°
62°
62°
38'
38'
45'
54'
OIl'
45'
110'
110'
53'
53'
III
III
III
III
III
III
III
III
E
E
27°
27°
34'
02'
OIl'
19'
110'
29'
18'
OJ'
29'
54'
2S'
011'
25'
11'
10'
lIaD
14' S
17'f 13' E
1140
34°
4,°
114°
45'
38'
20'
30'
21'
174° 30' E
174° :!B' E
61°
28°
ｾ＠
ｾ＠
27°
28°
ｾ＠
Ｔｾ＠
N
N
N
N
S
5
S
N
N
N
N
N
N
N
N
39°
39°
42°
49°
42°
73°
75°
75°
011°
04°
S
S
5
S
S
10° 12' III
10° 17' III
Ｑｾ＠
23' III
SOO 22' III
O 117' III
seO 00' III
goO 15' III
agO 46' III
goO 06' III
agO 47' III
esO 35' III
se
93°21'111
93° 19' III
93° 19' III
166° 55' E
174° 19' E
1?t' 36' E
1926
3338
659
1613
1500
1500
260
260
4822
4706
4829
146
59
282
42D
1378
595
1386
1358
605
860
841
BOil
810
11193
1760
7BO
1386
31
Table 23. Samples collected by the Woods Hole
ｏ｣ｾ｡ｮｯｧｲｰｨｩ＠
Institution.
See previous pege for explanation.
Genus
Program and
Station NlJItJer
WHOI F1
WHOI64
WHOI 66
WHOI 73
WHO! 85
WHOI 103
WHOI 119
WHOI 126
WHOI 128
WHOI 131
WHOI 142
WHOI 156
WHOI 159
1'12
C, 1'12
WHOl 162
LP2, 1'12
WHOI 167
LP2, 1'12
WHoI 169
LP1
WHOI 180
H
WHOI 189
l'tI, LP3** WHOI 209
l'tI, LP3
IdHOI 210
C**
IdHOI 236
C
WHOI237
C
WHOI 239
H, l'tI
WHOI 243
C, H
WHOI 245
l'tI
WHOI 287
l'tI
WHOI 291
l'tI
WHOI 293
H**
WHOI 295
LP2
WHOI 297
l'tI
WHOI 299
l'tI**
WHOI 321
l'tI
WHOI 326
H, l'tI
WHOI 328
l'tI
WHOI 330
H, l'tI
WHOI 334
H,LP2**,l'tI WHOI 340
l'tI
l'tI
l'tI
l'tI, LP3
l'tI
l'tI
LP3
l'tI
l'tI
l'tI
LP2
l'tI
Midpoint
Latitude
l'Iidpoint
L5!!:l9itude
l'Iidpoint
Oeeth (ml
39°
38°
38°
39°
37°
39°
32°
39°
39°
36°
10°
00°
07°
70°
70°
70°
70°
69°
70°
64°
66°
70°
67°
17°
29°
34°
34°
34°
34°
13°
12°
70°
70°
53°
53°
53°
52°
53°
54°
55°
54°
540
54°
55°
13°
14°
15°
17°
46°
70°
1500
2886
2802
1400
3834
2022
2159
3806
1254
2178
1710
3459
887
1493
975
587
205
1011
1597
2044
SOB
1002
1670
3B19
Location
Gay Head-Sermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda ·Transect
E. Gay Head-8ermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Off Senegal, Africa
Nr. St.Peter/St. Paul Rocks
Off Brazil
Off Brazil
Off Brazil
Off Brazil
Ofr lIIalvis Bay
Off lIIalvis Bay
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Argentine Basin
Argentine Basin
Argentine Basin
Argentine Basin
Argentine Basin
Eastern Caribbean Basin
Eastern Caribbean Basin
Eastern Caribbean Basin
Eastern Caribbean Basin
Eastern Caribbean Basin
Eastern Caribbean Basin
lIE Atlantic Ocean
lIE Atlantic Ocean
lIE Atlantic Ocean
lIE Atlantic Ocean
Central North Atlantic Ocean
ｾ＠
Atlantic Ocean
ｾ＠
ｾ＠
08°
22°
Ｒｾ＠
39°
39°
36°
36°
36°
37°
36°
13°
10°
aBO
08°
07°
07°
50°
50°
50°
50°
40°
38°
47'
48'
47'
47'
59'
44'
16'
37'
47'
29'
30'
46'
58'
59'
54'
03'
54'
00'
47'
43'
28'
33'
49'
37'
56'
16'
06'
58'
04'
45'
55'
12'
as'
as'
43'
43'
16'
N
N
N
N
N
N
N
N
N
N
N
S
S
S
S
S
S
S
N
N
S
S
S
S
5
N
N
N
N
N
N
N
N
N
N
N
N
45' W
06' W
09' W
43' W
26' III
37' III
32' W
46' III
45' W
5B' W
52' W
26' III
22' III
06' W
17' III
24' III
32' E
45' E
49' W
48' III
32' W
23' W
15' W
24' III
01' III
53' III
14' W
04' III
21'W
24' W
42' III
39' III
24' W
45' III
52' III
14' III
21' W
2707
4957
3864
1487
1011
516
2009
2B79
3859
4431
4632
4400
3310
32
New Zealand Oceanographic Institute, and Roger Lincoln, British
Museum, Natural History.
These latter specimens are mentioned only
briefly here and will be the subject of a future paper describing New
Zealand munnopsoid isopods.
REPORTING AND USE OF RATIOS
Many ratios are used in describing the species herein.
In order
to avoid the repetitive use of the word "times", ratios are reported
as a multiplier of the object of a telegraphic phrase in order to
indicate the size of the subject of the phrase.
For example, "endopod
length 2.2 width" means "the length of the endopod is 2.2 times its
width," or "article 2 of palp 0.86 mandibular body length" means "the
second article of the palp is 0.86 times the length of the mandibular
body."
Note that often nouns are used as modifiers of nouns without
adjectival endings; this practice improves the readability of the
necessarily dense telegraphese
ｾｳ･､＠
to describe the species.
When
used in this way, the modifier nouns will include larger sets to the
left so that reading left to right will take the reader from general
to specific, e.g. "male pleopod I distal tip inner lobe."
Each set
indicated b,y a noun may include a modifier to specify position or
appendage number.
Ratios are used because they accomplish two things.
First, they
provide a specific, unambiguous description of shape in a form that is
readily understood.
Second, they normalize the size of an appendage
or segment to the overall size of the specimen being used, thereby
imparting some generality to the measurement.
The ratios are derived
33
from measurements taken directly from the animals using a camera
lucida attachment on the microscope, or from drawings made of the
specimens.
The precision of the ratios is reduced in most cases to 2
significant figures in order to accommodate individual variation and
measurement error.
The ratios are meaningful in that they report the
shape of a particular body part, a shape that has been verified by
examining several specimens, or more for externally visible
characters.
Large departures from the reported ratio can be seen
easily, whereas small differences, say plus or minus 10 per cent,
require careful measurement.
Statistical significance, however, is
not implied by the use of ratios.
If the ratios are derived from more
than one specimen, their count is reported parenthetically immediately
after the ratio.
DEFINITION OF TAXA AND MORPHOLOGICAL TERMS
Species are identified using techniques developed and discussed
in previous papers (Wilson and Hessler, 1980; Wilson, 1983).
In
general, this involves the study of variation within and between
populations (samples) of similar animals.
Species level taxa were not
studied intensively for this work, because the main purpose was to
elucidate the higher level taxonomy of the ilyarachnoid eurycopids.
In fact, some of the species may include complexes of very similar
species; Mimocopelates longipes n.gen., n. sp., is suspected of being
one such case because it has a broad distribution similar to that of
the Eurycope complanata complex (Wilson, 1983b).
problems are left to future study.
These species level
34
Genera are the main focus of this work and are defined using a
system based on eurycopid morphology developed in Wilson and Hessler
(1980, 1981).
A glossary to the morphological terms used in this work
is provided in appendix 1.
Figure 1.4 shows the shows the overall
morphology of a typical munnopsoid, and figure 2.1 illustates terms
referring to cephalic morphology.
Generic characters are taken from the forms of the cephalon and
the natasome.
The cephalic characters, including the mandibles and
their articulation to the cephal on , show a great deal of variation
among the janiroidean isopod families, and seem to indicate important
differences in feeding life styles between groups of species.
The
natasome characters, such as the size and shape of the swimming leg
segments, are unique to (a synapomorphy of) the munnopsoid families
Ilyarachnidae, Eurycopidae, and Munnopsidae, and indicate the
locomotory life styles, of their bearers.
The natasome shows a great
deal of variation among these taxa (for example see figure 1.5), but
is constant among groups of species.
As such, the natasome characters
are ideal for generic definition within the munnopsoids.
Other
characters, such as the form of uropods and the ambulatory limbs (when
these legs have been seen; they typically break off during sampling
and processing) are also important in defining genera.
The goal of this morphological system is to define genera as
distinctive groups of species, separated (as Mayr (1970) wrote) from
other such groups by distinct gaps.
clades of similar species.
Genera are, therefore, defined as
We may be able to distinguish genera only
35
because intermediate species have become extinct, or because they
simply have not been collected yet, a common occurrence for deep-sea
taxa.
Although genera may be only a taxonomic convenience to help
categorize the evolutionary hierarchy, they may also include those
animals that go about their business in similar ways, and thus be of
potential interest to ecologists.
PREPARATION AND ILLUSTRATION OF SPECIMENS
All specimens for this study are stored in 80% or 95% ethanol.
For study, they were placed on depression slides in ethylene glycol,
which is miscible with ethanol.
The specimens were studied,
dissected, and illustrated using a Wild M5 dissecting stereomicroscope
or a Wild M20 compound microscope, both equipped with camera lucida
attachments.
Illustrations of the specimens were originally done in pencil,
and then inked by tracing onto translucent velum.
The illustrations,
of course, cannot include all the detail of the animals, although
effort was made to include all major surface structures, including all
setae.
When rows of setae were encountered, such as those on the
margins of the swimming pereopods, only a few representative setae
were drawn and positions of the the rest were indicated by a circular,
u-shaped, or v-shaped marks.
An open mark shows the direction that
the seta lies on the animal.
Some types of setae, such as plumose
setae and broom setae, have many fine setules that would not reproduce
well i f all were illustrated.
Therefore, setules on setae are
generally illustrated much more sparsely than they really are.
Some
36
cuticular structures, generally best studied with a scanning electron
microscope, were sometimes prominent on the specimens and were
partially drawn in order to accentuate cuticular form.
the drawings represents surface structures.
Most detail in
Frequent exceptions are
. the musculature and sperm tubes of malepleopods I and II, and
sometimes structures on the mandibles.
or represented b.1 dashed lines.
Subsurface detail is shaded,
If not otherwise noted, the
orientation of the illustrations is as follows.
illustrated in lateral view.
The maxillulae, maxillae, maxillipeds,
and pleopods are illustrated in ventral view.
illustrated in ventral view.
All the pereopods are
The antennulae are
37
TAXONOMY
COPERONUS New Genus
(Figures 2.1 - 2.5)
Type-Species.-Coperonus comptus new species
Generic Diagnosis.--Dorsal surface smooth, without spines.
Cephalic
anterior and lateral margin lightly calcified, not enlarged,
semicircular in frontal view.
in dorsal view.
Rostrum absent, vertex slightly convex
Frontal arch protruding anteriorly, with raised
flattened area adjacent to clypeal attachment; frontal arch angular in
frontal view.
Clypeus medial section triangular in frontal view;
dorsal apex higher than articulation with frons, slightly lower than
apex of flattened area on frons.
half that of cephalon.
Labrum anteriorly flattened, height
Body deepest and widest at pereonite 5.
Natasome compact; pereonites 5-7 with distinct articulations dorsally
I
but fused ventrally; pereonite 5 largest; pereonite 7 dorsally reduced
to thin strip.
Ventral surface of natasome enlarged at pereonite 5,
compressed at pereonites 6-7, with large ventromedial bump medial to
insertions of pereopods V.
Antennular article 1 with distinct medial
and lateral lobes; medial lobe rounded, longer than article 2; lateral
lobe flattened.
Antennal scale absent.
Mandible not highly
modified, without reduced functional areas: incisor process, lacinia
mobilis, and molar process with pointed cusps or denticles; molar
process distally concave; condyle roughly same length as molar
process, with support ridge extending from posterior edge of condyle
to posterolateral corner of mandibular
｢ｯ､ｹｾ＠
palp slightly shorter
38
than mandibular body.
Pereopodal bases I-IV increasing slightly in
length posteriorly, all longer than natapodal bases V-VII; basis V
shortest and stoutest, bases VI-VII increasingly longer and less stout
posteriorly.
Pereopods V-VI natatory, with broad carpi and propodi.
Pereopod VII near length of pereopod VI but carpus and propodus only
slightly broadened, with fewer and shorter plumose setae on margins.
Dactylus of pereopod V small, lenticular; dactyli VI-VII long, thin.
Female pleopod II with small slit in distal tip.
Uropod short and
stout, recessed into posteroventral margin of pleotelson; protopod
broader than long; both rami shorter than protopod.
Derivation of Name.--Coperonus (Greek, masculine) may be construed to
mean "isopod furnished with oars."
Composition.--Coperonus comptus n. sp., C. nordenstami n. sp., C.
frigida (Vanh8ffen, 1914).
Remarks.--Coperonus is the least modified genus of all the
ilyarachnoid eurycopids.
Although its members have the short, broad
head and reduced frontal area characteristic of the Ilyarachnidae and
the ilyarachnoid eurycopids, the pereon and pleotelson are much more
characteristic of the Eurycopidae in the posteriorly rounded, bulletshaped appearance.
The uropods are also very eurycopid-like, although
somewhat reduced and modified in their position.
The only feature of
the posterior half of the body that unequivocally identifies Coperonus
as a member of the ilyarachnoid eurycopids is the reduction of
pereonite 7 and its limb.
Figure 2.1.
Coperonus comptus new genus, new species.
male, lateral and dorsal views, scale bar 1.0 mm.
A-B, holotype
C-F, cephalon,
paratype brooding female, bl 2.8 mm, antennula and antenna removed
from one or both sides to show frons.
oblique view.
E, anterior view.
C, lateral view. D, frontal
F, ventral view, maxilliped removed
to show shape of mandibles and ventral cephalon.
G, natasome,
paratype male, bl 2.9 mm, ventral oblique view showing form of ventral
surface and shapes of pereopodal bases.
Labels on figure: a - apex of
anterior dorsal margin; c - clypeus; f - frontal ridge; I - labrum; m
- mandible; mxI - maxillula; mxII - maxilla; ok - oral knob (supports
maxillipeds above mouthparts shown); p - paragnaths; plI - male
pleopod I; pIlI - male pleopod II; ur - uropod.
40
41
Coperonus may be distinguished from the other ilyarachnoid
eurycopids by its rounded natasome and relatively unmodified uropod.
A large pereopod VII that retains some of its natatory function is
also useful for identification, clearly separating Coperonus from
Lipomera Tattersall, 1905a, and Mimocopelates n. gen., which lack
functional seventh pereopods.
Coperonus does not have the decidedly
Ilyarachna-like appearance and flexed body of Hapsidohedra n. gen., or
the low cephalon and terminal uropods of Lionectes n. gen.
In addition to the type-species, Coperonus comptus n. sp., the
genus includes species originally placed in Eurycope.
syntypes of
!.
Most of the
frigida Vanh8ffen, 1914 belong in Coperonus.
Vanh8ffen
(1914) described 10 individuals under this species name, although one
of the specimens belongs to Lionectes n. gen. (see discussion after
diagnosis of Lionectes).
In addition to the overall similarity of the
body shape of the large specimen figured by Vanh8ffen (1914, his
figure number 122), the maxilliped is practically identical to that of
the type-species of Coperonus, and the male pleopods are similar, but
not identical (Vanh8ffen, 1914, his figure number 123b-d).
Because of
these generic similarities, the 9 large specimens of the species
frigida are assigned to the genus Coperonus.
A lectotype of C.
frigida is currently undesignated.
Nordenstam (1933) described Eurycope sp. cf. frigida but, for
some undisclosed reason, did not feel confident enough to give it a
new species name, even though he examined Vanh8ffen's types and found
his specimens different.
!.
sp. cf. frigida Nordenstam, 1933 is
42
definitely a member of Coperonus; the illustrations (Nordenstam, 1933,
his fig. 78) clearly show the distinctive body shape and the
heterogeneous composition of natatory pereopods, with a reduced but
still natatory pereopod VII, found only in Coperonus.
Because
Nordenstam's specimens are sufficiently well illustrated to establish
their specific identity, they are assigned to a new species of
Coperonus,
Q. nordenstami,
in honor of their first describer (see
diagnosis below).
Coperonus is a South Atlantic and Antarctic genus.
to
In addition
Q. frigidus (Vanh6ffen, 1914) and Q. nordenstami n. sp. found off
East Antarctica and South Georgia Island, respectively, three species,
one of which is
Q. comptus n. sp., have been found in the Weddell Sea
and Palmer Penninsula area, and three species were collected by Woods
Hole Oceanographic Institution expeditions off Argentina and Brazil.
Coperonus comptus new species
(Figures 2.1 - 2.5)
Holotype.--Copulatory male, bl 2.6 mm, ambulatory pereopods and
antennae missing, USNM.
Paratypes.--Preparatory female, USNM.
male, ZMUC.
Preparatory female, copulatory
Preparatory female, copulatory male, MNHNP.
90
individuals, some dissected for description SIO.
Type-Locality.--WHOI 236, 360 27.0-28.1' S, 53 0 31.0-32.3' W, 497-518
m, collected 11 March 1971 during R/V Atlantis cruise number 60.
43
other Material.--WHOI 239, 37 individuals.
WHOI 237, 36 individuals.
WHOI 245, 2 .fragments.
General Distribution.--Argentine Basin in the southwestern Atlantic
Ocean, 497-2707 m.
Derivation of Name.--Comptus means nelegantn in Latin.
Diagnosis.--Apex of cephalon only slightly convex, neither linear nor
strongly convex.
Pleotelson posterior margin in dorsal view smoothly
arced, not nvn or heart-shaped.
than article 2.
Male antennular article 3 shorter
Maxillipedal epipod distal tip pointed, not rounded.
Pereopod VI only slightly shorter than pereopod V, pereopod VI length
0.94 pereopod V length.
Male pleopod I distal tips concave in ventral
view, with broadly angular inner and outer lobes.
Description.--Adult body length 2.5-2.8 mm (5 inds), length 1.9-2.1
width (4 inds).
Body setation (fig. 2.1A): Natasome with tiny setae on dorsal and
lateral surfaces; other dorsal surfaces with only scattered fine
setae.
Cephalon (fig. 2.1C-F): Dorsal length 0.31 width, length 0.42 height.
Ventral margin at posterior articulation of mandible with distinct
indentation or notch.
Antennula (fig. 2.2A-B): In males length 0.35-0.36 (2 inds) body
length; in females, 0.23-0.26 (2 inds).
Male antennula with 14
44
Figure 2.2.
Coperonus comptus new genus, new species.
A, right
anterior section of cephalon showing antennula and basal articles of
antenna, holotype male.
B, right antennula.
C-F, H-I, lett mandible.
distal section of palp.
spine row, ventral view.
view.
B-N, paratype brooding female, bl 2.8 mm.
C, dorsal view.
E, incisor process, lacinia mobilis, and
F, incisor process and lacinia mobilis, plan
G, incisor process, right mandible, plan view.
process, anterior and posterior views.
maxilla.
L, paragnaths.
D,
H-I, molar
J, right maxillula. K, right
M-N, right maxilliped, enlargement of
endite and whole limb, respectively.
Ｌｾ＠
45
H
46
articles and approximately 6 aesthetascs distally; remale antennula
with 10-11 articles and 2-5 aesthetascs distally. Article 1 medial
length 1.1 width in male, 0.75-0.78 (2 inds) in remale; medial lobe or
both sexes with approximately 6 denticulate setae having long sensilla
and 3-4 denticles on distal tips.
Articles 2 and 4 with broom setae.
Articles 2 and 3 only slightly geniculate at articulation.
Article 2
slightly shorter than article 1 medial lobe in remales, length 0.7
medial lobe length in males.
Article 3 length 0.61 article 2 length
in male, 0.71 (2 inds) in remales.
Mandible (rig. 2.2C-I): Normally developed. Both mandibles with 3
distinct cusps on incisor processes.
Lacinia mobilis reaching to tip
or incisor process, with 4 cusps. Lert spine row with 7 members.
Molar process distal end with low circumgnathal denticles, lacking
large pointed cusp on ventral margin; posterior margin with 3
rlattened setulate setae; triturating surrace with approximately 4
sensory pores.
Condyle length 0.27. mandibular body length.
Palp
second article length 0.49 mandibular body length.
Maxillula (rig. 2.2J): Normally developed.
Inner endite width 0.74
outer endite width.
Maxilla (rig. 2.2K): Normally developed.
Outer lobes shorter than
inner lobe.
Maxilliped (rig. 2.2M-N): Basis with 4 receptaculi and 4 ran setae
distally, medial ran seta more robust, with rewer and broader branches
than 3 lateral ran setae. Endite length 0.53 total basis length.
Palp
47
article 2 width greater than 2 times endite width, lateral length 1.6
medial length.
Palp article 3 lateral length 0.19 medial length.
Epipod short, narrow, and distally pointed; length 0.81 basis length;
length 2.9 width.
Pereopodal Bases (fig. 2.1G, 2.3C): Bases I-IV length-body length
ratios in male holotype 0.22, 0.24, 0.23, 0.26, respectively; all
similarly robust.
Bases V-VII in brooding female shorter than bases
I-IV; length-body length ratios 0.11, 0.18, 0.19,_ respectively.
Pereopod I (fig. 2.3A-B): Sexually dimorphic.
In males, pereopod I
length 0.67 body length, with robust basis and ischium, and with tuft
of setae on proximal venter of ischium; ischium length 0.48 basis
-length.
In females, pereopod length 0.63 body length, with thin basis
and ischium, and lacking tuft of setae on ischium; ischium length 0.43
basis length.
Natatory Pereopods (fig. 2.3D-F): Natapods heterogeneous in form:
pereopod V strongly natatory; pereopod VII resembling walking leg but
with slightly broadened carpus and propodus, and with reduced plumose
setae; pereopod VI intermediate in form.
Bases, propodi, and dactyli
increase in length posteriorly; ischia, meri, carpi, and natatory
setae on carpus and propodus decrease in length posteriorly; width of
carpus and propodus decrease posteriorly.
Pereopod V-VII length-body
length ratios 0.70, 0.66, 0.60, respectively.
width ratios 1.1, 1.3,
ＳＮｾＬ＠
Carpi V-VII lengtn-
respectively. Propodi V-VII length-width
ratios 1.6, 2.5, 5.6, respectively.
Dactylus V tiny, with no distal
Ｍｾ
claw (or unguis); dactyli VI-VII much longer, with claw.
----------------
Figure 2 •.3.
Coperonus oomptus new genus, new speoies.
A, right
pereopod I, male from WHOI 2.39, bl 2.7 mm.
B, D-F, pereopods,
brooding female from WHOI 2.39, bl .3.0 mm.
B, right pereopod I.
bases of pereopods I-IV, paratype male, bl 2.9 mm.
C,
D-F, natatory
pereopods V-VII to same soale, with enlargements of olaws of daotyli
VI-VII.
49
c
50
Male Pleopod I (fig. 2.4!-B).
narrowing midlength.
Pleopod widest proximally, abruptly
Length 2.9 width; dorsal orifice 0.09 total
length from distal tip. Distal tips bilobed, rounded in lateral view,
slightly concave in ventral view.
Fine setae on distal third of
ventral surface, and 2 paired groups of setae on distal tip.
Male Pleopod II .(fig. 2.40):
Protopod broad proximally, narrowing to
small rounded lobe distal to exopod; length 1.5 width.
setae on distolateral margin of protopod.
Small plumose
Stylet short, half length
of protopod; sperm duct opening at stylet midpoint.
Exopod bare,
without tuft of fine setae.
Female Pleopod II (fig. 2.4G-I): Keel deep, sharply defined from
lateral fields.
Dorsal surface with scattered setae; distolateral
margins with small plumose setae.
length.
Length 0.81 width; depth 0.47
Apex anterior to length midpoint, lacking large seta.
Pleopod III (fig. 2.4D): Exopod extending to distal tip of endopod,
with 2 long plumose setae, and 1 simple setae on distal tip.
Uropod (fig. 2.41): Protopod medial length 0.61 distal width.
Exopod
0.69 endopod length.
Distal
Endopod 0.76 medial length of protopod.
margin of protopod with group of unequally bifid setae on medial lobe,
and few setae laterally.
51
Figure 2.4.
Coperonus comptus new genus, new species.
paratype male, bl 2.9 mm.
mm.
A-C,
D-J, paratype brooding female, bl 2.8
A-B, male pleopod I, ventral and lateral views, with
enlargement of distal tip, some setae shown only by basal attachments
for clarity of reproduction.
C, left male pleopod II, with enlargement
of stylet; fringing setae on distolateral margin are plumose.
left pleopods III-V.
G-I, female pleopod II, ventral, lateral,
and posterior views, respectively.
J, right uropod.
D-F,
52
53
Remarks.--Coperonus has three described species and 5 undescribed
species known to me.
Q. comptus can be identified among these only by
using a combination of characters: the cephalic and pleotelson form,
the male antennulae and pleopods, the comparative sizes of pereopods V
and VI, and the maxillipedal epipod •. It is restricted to the
Argentine Basin from just below the shelf break to below 2000 m.
54
Coperonus nordenstami new species
sp. cf. frigida Nordenstam, 1933.
ｓｹｮｯｭＮＭｾ｣ｰ･＠
Syntypes.--Two small damaged females.
Type-Locality.--Swedish Antarctic Expedition station 34.
South
Georgia Island, off the mouth of Cumberland Bay, 540 11' S, 360 18' W,
252-310 m, 5 June 1902. Sediment gray clay with a few stones.
General Distribution.--South Georgia Island.
Known only trom type
locality.
Derivation of Name.--This species is named after its describer, ike
Nordenstam.
Diagnosis.--Apex of cephalon linear.
dorsal view appearing as rounded "V".
rounded.
Pleotelson posterior margin in
Maxillipedal epipod distal tip
Pereopod VI only slightly shorter than pereopod V.
Remarks.--The above diagnosis is somewhat limited because males of
Coperonus nordenstami n. sp. are unknown.
are different from
The females of this species
Q. comptus in the form of the pleotelson, the
cephalon, and the maxillipedal epipod (Nordenstam, 1933, his figure
78).
55
HAPSIDOHEDRA new genus
(Figures 2.5 - 2.9)
Type-Species.--Hapsidohedra ochlera new species
Generic Diagnosis.--Dorsal surface of body without spines.
Cephalic
lateral and frontal margins thickened and calcified; frontal area
semicircular in frontal view, without rostrum or medial protrusions;
vertex linear, without anterior or posterior curves.
Clypeus thick
and heavily sclerotized laterally; medially arched, anterior-most midpoint higher than attachment to frons.
Labrum high and anteriorly
flattened, height three quarters that of
｣･ｰｨ｡ｬｯｮｾ＠
Body deepest at
pereonite 5; broadest at posterior margin of pereonite 5. Natasome
highly modified: dorsal surface greatly arched, so that pleotelson at
right angle to axis of ambulosome; pereonite 7 reduced and
dorsomedially fused to pereonite 6; sutures between pereonites 5-7
present ventrally.
margin.
Pleotelson subtriangular, widest at anterior
Antennular first article broad, with distinct medial and
lateral lobes; medial lobe rounded, lateral lobe dorsoventrally
flattened; flagellar articles as few as 2 in adult female.
article 3 without distinct scale.
Antenna
Mandible highly modified: incisor
process with reduced rounded teeth; lacinia mobilis flattened, much
smaller than incisor process, with reduced teeth; left spine row
compressed next to base of lacinia, spines much shorter than lacinia;
molar process massive, with broad, bilobate triturating surface
lacking circumgnathal incisive ridges or denticles, setal row with few
closely adjacent setulate setae; condyle enlarged, heavily
56
sclerotized, extending trom distal surface of molar process to
proximity of posterolateral corner of mandibular body, length greater
than half mandibular body length; palp thin, shorter than mandibular
Pereopodal bases lengths heterogeneous: bases II and III
body.
subequal and shortest, bases IV and VI subequal and longest, bases I,
V, and VII intermediate in length.
broad carpi and propodi.
Pereopod V and VI natatory, with
Pereopod VII thin, reduced, with narrow
carpus and propodus, and few natatory setae.
Dactyli of pereopods V-
VI thin, curved, lengths subequal; dactylus VII much longer, thin
also.
Pleopod II of female with slit dividing distal tip into two
halves.
Uropod with broad, flattened, oval protopod and 1 short
ramus; uropod inserts subterminally and ventrally, covering anus with
protopod.
Derivation of Name.--Hapsidohedra (Greek, fe.minine) means "vaulted
rump, If referring to the high, arched natasome of species of this
genus.
Composition.--Hapsidohedra ochlera n. sp.;
ｾ＠
aspidophora (Wolff,
1962) •
Remarks.--Hapsidohedra is the most ilyarachnid-like of the
ilyarachnoid eurycopids.
The broad, dorsally tubular and robust
cephalon, the triangular natasome tipped with a leaf-like uniramous
uropod, and a non-natatory pereopod VII are all seen in the
Ilyarachnidae.
Indeed, Wolff (1962) chose to place the species
aspidophora in Ilyarachna, apparently overlooking characters that
Ｍｾ
conflicted with his diagnosis of the Ilyarachnidae: a large, rounded,
Ｍｾ
57
non-setiferous mandibular molar; elongate bases of pereopods III-IV;
and a bilobate, thick antennular article 1.
This species provided the
impetus for this work; it is shocking that an animal can resemble the
members of a reasonably well-defined and specialized taxon, and yet
can lack the features that define the taxon.
If this genus was the
only one known of the ilyarachnoid eurycopids, the current definition
of the Ilyarachnidae would be seriously deficient.
The other genera
described in this paper, however, show that Hapsidohedra is part of an
evolutionary line separate from the ilyarachnids, and that convergence
to a similar body form is responsible for the resemblance.
Hapsidohedra shares the several important characters with the
other ilyarachnoid eurycopids.
different from ilyarachnids.
These characters also make the genus
The molar process is not reduced, but is
enlarged (taken to an extreme in this genus).
III-IV are similar in length to basis II.
The bases of pereopods
Pereonites VI and VII are
fused dorsally, but Hapsidohedra retains the primitive separation of
the ventral surfaces of the natasomites.
The clypeus is angular and
its anterior apex is higher than its insertion on the cephalic frons.
A11 ilyarachnoid eurycopids have almost identical pleopods III and IV,
and Hapsidohedra is no exception.
The frons of Hapsidohedra is distinctive, but the same general
cephalic form is found in all the ilyarachnoid eurycopids: the frontal
area is reduced, with a disappearance of the cephalic arch and the
frontal area above it.
As in most ilyarachnoid eurycopids, the
anterodorsal dorsal margin of the cephalon has become heavier,
58
providing a support bridge for the mandibular attachments.
In
contrast, the frontal arch of the Ilyarachnidae, in which Hapsidohedra
was previously placed, has become broadened under the antennae,
providing the main part of the mandibular support bridge.
This will
be discussed in more detail in chapter 6.
other characters help seperate Hapsidohedra from the other
ilyarachnoid eurycopids.
The leaf-like uropod is most useful for
separating if from the other genera.
This genus is closely related to
Coperonus'in the general form of the natasome, but its Ilyarachna-like
appearance and massive mandible make it easy to separate from that
genus.
Hapsidohedra is superficially most similar to Lipomera in the
form of the uropod and the cephalon, but Hapsidohedra has a distinct
ramus on the uropod, and a functional pereopod VII.
Hapsidohedra
lacks the terminal uropods and recessed pereonite 7 of Lionectes, and
the highly modified natasome of Mimocopelates.
Hapsidohedra has only two described species at present, H.
ochlera n.sp. from bathyal waters of the Caribbean Sea off northern
South America, and
ｾ＠
aspidophora (Wolff, 1962) from shallow bathyal or
deep shelf waters off East New Zealand.
At least 3 other undescribed
species have been collected in the North and South Atlantic, and the
Gulf of Mexico.
This genus may be regarded as cosmopolitan in view of
the wide occurrences in the Atlantic and Pacific Oceans.
59
Figure 2.5.
Hapsidohedra ochlera new genus, new species.
A-B,
holotype preparatory female, lateral and dorsal views, scale bar 1.0
mm.
C, paratype male, lateral view, same scale as female.
D,
paratype male, enlargement of left lateral margins of pereonites 1-4
and pereopodal bases, showing relative sizes of bases.
holotype female.
E, pleotelson,
F, natasome, lateral oblique view, showing form of
ventral surface and relative sizes of bases V-VII, paratype female,'
bl· 1.7 mm.
60
A
61
Hapsidohedra ocblera new species
(Figures 2.5 - 2.9)
Holotype.--Preparatory female, bl 2.5 mm, all pereopods except left
Per VII missing, USNM.
Paratypes.--Preparatory female, bl 2.3 mm; brooding female, bl 2.2 mm;
male, bl 1.7 mm: USNM.
ZMUO.
Brooding female, bl 2.3 mm; male, bl 1.6 mm:
Brooding female, bl 2.3 mm; male, bl 1.6 mm: MNHNP.
58
individuals, some dissected for description, SIO.
o
0
Type-Locality.--WHOI 295, 8 04.2' N, 54 21.3' W, 1000-1022 m, 8
February 1972, collected with an epibenthic sled.
Other Material.--Five specimens, WHOI 293.
Preparatory female, LGL84
04/6; fragmentary copulatory male, LGL84 02/2.
General Distribution.--Off Surinam, South America, 1000-1518 m, and in
the Gulf of Mexico off Louisiana, 595-1386 m.
Derivation of Name.--Ocblera (Greek, feminine) means "troublesome."
The specific epithet refers to the "troublesome", but superficial
similarity of this species to the Ilyarachnidae.
Diagnosis.--Antennular article 2 longer than medial lobe.
Mandible
with reduced spine row on incisor process; molar process with 3
serrate setae distally.
Keel of female pleopod II terminating
abruptly anterior to distal tip, with recurved or quadrate posterior
margin in lateral view and with posteriorly directed denticles on
ventral margin.
Figure 2.6.
Hapsidohedra ochlera new genus, new species.
A-B,
cephalon, frontal oblique and lateral views, antennula and antenna
removed to show frons, paratype preparatory female, cephalon fragment
only.
C-J, paratype brooding female cephalon fragment.
C-D,
cephalon, anterior and ventral views, dorsal setation not shown.
left mandible, dorsal and medial views.
mobilis, and spine row, ventral view.
mobilis, plan view.
G, incisor process, lacinia
H, incisor process and lacinia
I, molar process, posteromedial view.
process, right mandible.
E-I,
J, incisor
63
o
Ｏｾｈ＠
I
J
64
Description.-Body Characters (fig. 2.5A-C,E): Adult body" length 1.72.5 mm, length (measured along curving body axis) 2.8 width in
holotype female. Pleotelson plan ventral view length 1.0-1.1 width.
Body Setation (fig. 2.5A,C,E-F): Cephalon with single large simple
seta.
Dorsal surface of ambulatory pereonites with sparse row of
simple setae near anterior margins.
with row of simple setae.
Anterior margin of pereonite 5
Ventrolateral margin of pleotelson with
thick row of plumose setae.
Cephalon (fig. 2.6A-D): Dorsal length 0.42 width, length 0.49 height.
Antennula (fig. 2.7A-C): Length 0.31-0.28 body length in males (2
measured), 0.15 in holotype female.
Male antennula with 12-16
articles, approximately 6 aesthetascs distally.
6 articles and only 1 aesthetasc.
Female antennula with
Article one medial length 0.93
width in male, 0.79 in female; both sexes with lateral row of
approximately 5 large setae; medial lobe with 4-5 large unequally
bifid or smaller broom setae.
Articles 2 and 4 with broom setae.
Articles 2 and 3 decidedly geniculate at articulation.
Article two
0.62 medial length of article one in male, 0.76 in female.
Mandible (fig. 2.6E-J): Left incisor process with 4 cusps, with gap
between dorsal cusp and three ventral cusps.
Right incisor with
single large cusp, and low cusps dorsally and ventrally.
mobilis flattened, with 4 teeth.
Lacinia
Left spine row with approximately 5
simple members, distinctly shorter than lacinia mobilis; right spine
row with two members.
Molar process with three closely-clumped
65
Figure 2.7.
Hapsidohedra ochlera new genus, new species. 'A -B, left
antennula, dorsal and lateral views, paratype male, bl 2.0 mm.
left antennula, paratype preparatory female, bl 2.0 mm.
paratype brooding female cephalon fragment.
maxillula.
F, left maxilla.
endite distal tip_
0,
D-G,
D, paragnaths.
E, left
G, right maxilliped with enlargement of
66
\
\
\
,
\
\
,
\
67
setulate setae.
Condyle length 0.54 mandibular body length.
Palp
second article length 0.43 mandibular body length.
Maxillula (fig. 2.7E): Normally developed.
Inner endite 0.64 width of
outer endite.
Maxilla (fig. 2.7F): Normally developed.
Outer lobes distinctly
shorter than inner lobe.
Maxilliped (fig.
epipod.
ｾＮＷｇＩＺ＠
Coxal plate large, nearly as long as width of
Endite with 4 receptaculi medially and 5 fan setae distally.
Palp article 2 lateral length 1.1 endite lateral length; lateral
length 1.7 medial length.
length.
Palp article 3 lateral length 0.29 medial
Epipod outline bean-shaped, with rounded lateral and distal
margins; length 1.5 width; distal margin with single simple seta.
Pereopodal Bases (fig. 2.5D,F; 2.8A-D): In female, bases I-VII
length/body length ratios 0.19, 0.16, 0.17, 0.23, 0.19, 0.23, 0.20,
respectively.
In male, ratios for bases I-IV 0.18, 0.17, 0.17, 0.23.
Male bases III-IV more robust than in female.
Pereopod I (fig. 2.8A): Total length 0.77 body length.
subequal to basis length.
Carpus length
Carpus and propodus thin, paucisetose.
Natatory Pereopods V-VI (fig. 2.8B-C): Total lengths 0.69, 0.71 body
length, respectively.
Ischia lengths 0.75, 0.60 bases lengths.
length/width ratios 1.4, 1.4.
Carpi
Propodi length/width ratios 2.0, 2.2.
Dactyli short, curved, thin, lengths 0.47, 0.50 propodi lengths.
68
Figure 2.8.
Hapsidohedra ocblera new genus, new species.
pereopod I, paratype preparatory female, bl 1.8 mm.
natatory pereopods V-VI, paratype male, bl 2.0.
ｾＬ＠
VII, paratype preparatory female, bl 2.0 mm.
holotype female.
A, left
B-C, right
D, left pereopod
E, right uropod, in
69
E
\
'---'--"
'
\. \
'\
,
{
I
70
Pereopod VII (fig. 2.8D): Total length 0.65 body length.
0.27 total length.
Basis length
Carpus and propodus narrow, with fewer setae on
margins than on anterior natatory limbs; length/width ratios 5.7, 4.7
respectively.
Dactylus long, thin, curved, length 1.2 propodus
length.
Male Pleopod I (fig. 2.9B): Fused pleopod pair long, thin, widest near
proximal end, length 3.4 width; at dorsal orifice length 5.8 width.
Distal tip bluntly rounded, almost quadrate.
continuous, marked only by rounded angles.
Inner and outer lobes
Distal tip with setae
dorsally, ventrally, and more proximally along midline.
Setae thick
and tubular proximally, narrowing abruptly at midlength, and thin,
whip-like distally.
Remainder of ventral surface without setae.
Male Pleopod II (fig. 2.90): Protopod long, narrow, distally rounded;
length 3.6 width; lateral margin with 10 large plumose setae; distal
and distolateral margin with short, fine, simple setae; 4 long simple
setae on ventral surface.
distal tip.
Endopod inserting 0.34 protopod length from
Stylet not extending to distal tip of protopod, with
short sperm duct, length 0.46 protopod length.
Female Pleopod II (fig. 2.9A): Opercular fused pleopod pair narrow,
horseshoe shaped in dorsal view,
widest midlength.
Keel thin, deep, with denticles along ventral margin.
pair depth 0.33 length.
Length 1.9 width.
Fused pleopod
Lateral margins with 8 plumose setae.
Long
simple setae on distoventral edge, and on posterior half of keel.
Distal tip slit length 0.11 total fused pleopod pair length.
Figure 2.9.
Hapsidohedra ochlera new genus, new species.
A, female
pleopod II, ventral and lateral views, paratype preparatory female, bl
2.0 mm.
B-F, pleopods, paratype male, bl 2.0 mm.
with enlargement of distal tip.
of stylet.
D, right pleopod III.
B, pleopod I,
0, left pleopod II, with enlargement
E-F, left pleopods IV-V.
72
B
73
Pleopod III (fig. 2.9D): Exopod longer than endopod, distally rounded,
with long thin simple setae on lateral margin, shorter thin, simple
setae on medial margin, and two long plumose setae distally having
thiak simple seta between them.
setae.
Endopod with three long plumose
All plumose setae longer than exopod.
Pleopod IV (fig. 2.9E): Exopod short, rounded, approximately half
length of pleopod length; single long plumose seta on distal tip.
Uropod (fig. 2.8E): Length 0.28 (male) to 0.29 (female) pleotelson
length.
Single ramus length 0.43 (male) to 0.37 (female) protopod
length.
External margins of protopod with large setae.
Distal tip of
ramus with 2 large and several small broom setae.
Remarks.--Hapsidohedra ochlera is most readily identified by the form
of the keel of the female pleopod II that has posteriorly directed
denticles on ventral margin and an anteriorly recurved or truncate
posterior margin.
The shape of the proximal article of the antennula
is useful as well.
This species has been found on shallow bathyal bottoms in the
Gulf of Mexico and in the Southern Caribbean Sea.
It will be
interesting to discover whether it is continuously distributed, or
whether the species is made of disjunct populations interrupted by
barriers such as the Yucatan Penninsula.
74
Hapsidohedra aspidophora (Wolff, 1962)
(Figure 2.10)
Synonym.--Ilyarachna aspidophora: Wolff (1962), p. 106-108.
Holotype.--Brooding female with about 20 embryos in marsupium, bl 3.2
mm, body width 1.4 mm (not seen by me).
No other types.
Type-Locality.--R/V Galathea station 639, off East New Zealand, 370
31' S, 1770 08' E, 213 m, bottom temperature circa 14.70 C (see Brunn
(1959) for more information).
Diagnosis.--Antennular article 2 shorter than medial lobe.
Mandible
lacking spine row on incisor process; molar process with only 1
serrate seta distally.
Keel of female pleopod II dorsally and
distally setose, lacking denticles on ventral margin, and sloping
smoothly into distal tip.
Remarks.--Hapsidohedra aspidophora is known from only a single, now
partially dissected, brooding female (Wolff, 1962).
It is much larger
than all the specimens of H. ochlera, and is different in the form of
the female pleopod II and the antennula.
The mandibular characters,
although less useful for sorting purposes, may also be useful for
distinguishing H. aspidophora from
aspidophora is unknown.
ｾ＠
ochlera.
The male of
ｾ＠
75
Figure 2.10.
Hapsidohedra aspidophora (Wolff, 1962).
and lateral views of holotype, after Wolff (1962).
A-B, dorsal
76
A
B
77
Hapsidohedra aspidophora is known from surprisingly shallow (213
m) and warm (140 C) waters off East New Zealand.
It will be of
considerable biogeographic interest to know the full range of this
species and its preferred hydrographic regime. !!. aspidophora may be
living under conditions similar to the deep-sea isopod fauna found in
shallow (50 m) water in the Mediterranean Sea (Hessler and Wilson,
1983) •
78
LIONECTES New Genus
(Figures
2.11 - 2.14)
Type-Species.--Lionectes humicephalotus new species.
Generic Diagnosis.--Dorsal surface smooth, without spines; in lateral
view, dorsal surface forming smooth arc from cephalon to pleotelson.
Cephalic anterior and anterolateral margins thin, dorsally flattened
in frontal view.
view.
Rostrum absent, vertex slightly convex in dorsal
Frontal arch between antennulae reduced, only slightly
protruding, rounded dorsally, not heavily calcified.
Clypeus medial
section triangular in frontal view; broad, rounded dorsal apex of
clypeus roughly horizontal, not sloping posteriorly to articulation
with frons, lower than apex of frontal arch.
Labrum high and
anteriorly rounded, approximately three-quarters height of cephalon.
Body deepest at pereonite 5.
Natasome compact, conical in dorsal plan
view; dorsal surface of pereonites 5-7 distinctly articulated
laterally, indistinctly articulated medially between pereonites 5 and
6, and fused medially between pereonites 6 and 7; pleonite 1
articulating margins distinct; pereonite 7 reduced, not reaching
lateral margin of natasome.
Ventral surface of natasomal pereonites
smoothly rounded, with indistinct or absent articulations between
segments; insertions of pereopods VII medial to insertions of
pereopods VI; posterior edge of pereon recessed into pleotelson.
Antennular article 1 with distinct medial and lateral lobes; medial
lobe rounded, longer than article 2; lateral lobe dorsoventrally
flattened.
Antennal scale absent.
Mandible somewhat modified: spine
79
row with few, posteriorly reduced members; molar process broad,
distally rounded, with thin cuticle, lacking denticles, and with only
1 distal setulate seta; condyle enlarged, longer than molar process,
with support ridge extending from posterior edge to protruding
posterolateral oorner of mandibular body; ventromedial region of
mandibular body reduced, not protruding; palp not reduced, with robust
segments.
Pereopodal bases lengths heterogeneous:
bases I, II, III,
and V lengths similar, shortest; basis VII longest; bases IV and VI
lengths similar, intermediate lengths.
Pereopods V-VI natatory, with
broad carpi and propodi; pereopod V only slightly larger than pereopod
VI; dactylus V tiny, rudimentary; dactylus VI-VII long and thin.
Pereopod VII resembling walking leg, with few plumose setae on ventral
margin of carpus only.
slit.
Female pleopod II distal tip entire, lacking
Uropods terminal on pleotelson, visible in dorsal view,
projecting from semicircular distal tip of pleotelson;
protopod
flattened, oval, dorsolaterally convex, with marginal whip setae;
endopod large, fat; exopod small but distinct; both rami shorter than
protopod.
Derivation of Name.--Lioneotes (Greek, masculine) means "smooth
swimmer," referring to the very smooth dorsal surface of members of
this genus.
Remarks.--Lioneotes is a member of the group of ilyaraohnoid eurycopid
genera that have seventh pereopods resembling walking legs; in
addition to this genus, the group inoludes Coperonus and Hapsidohedra.
Beoause this group has functional seventh pereopods, it is distinct
80
trom the genera Lipomera and Mimocopelates which lack seventh
pereopods (or at least tunctional ones).
Although these three genera
resemble each other in general torm ot the cephalon and the natasome,
each one has specializations, or lack thereot, that make them
distinct.
Lionectes is identitied b,y a smooth almost seed-like
habitus in dorsal view, terminally-placed uropods that protrude trom a
posterior opening in the pleotelson, a dorsoventrally tlattened head,
and a distal section ot the pereon that is recessed into pockets in
the pleotelson.
Details ot the mandible and the trons are also usetul
tor identifying this genus.
The composition ot Lionectes is currently complicated by Eurycope
trigida Vanh8tten, 1914, described trom 10 specimens collected at
"Gauss Station n (8/II/1903) in tairly shallow water ott East
Antarctica.
Vanh6tten's (1914) illustrations (p. 590) show two
animals, one listed as an adult and another listed as a juvenile,
although two species may actually be represented.
The "adult"
probably belongs to Coperonus and the njuvenile" may be a member ot
Lionectes.
The adult is much larger than the supposed juvenile,
2.5 mm versus 1 mm, and the juvenile is !!21 a manca.
In addition the
juvenile has a number ot characters that conflict with the adult: the
cephalon is anteriorly more compressed; the pleotelson is straight
sided, not rounded; the antennulae are much shorter, with compressed
tlagellar articles; and the uropods project into dorsal view trom the
tip ot the pleotelson.
Unfortunately, Vanh8tten (1914) did not
describe the uropods.
The njuvenile" has one characteristic, in
addition to the above difterences with the "adult," that make its
81
identification as a species of Lionectes more certain: the seventh
pereopods, which resemble walking legs, are placed medial to the sixth
walking legs and appear in Vanh6ffen's drawing (his figure 123A) to
protrude from above the pleopod II, indicating that the posterior part
or the pereon is recessed into the pleotelson - a diagnostic character
of Lionectes.
The larger individuals (Vanh6ffen's figures 122A, 123C-
D) are assigned to Coperonus owing to similarities in the overall body
shape and size, in the length of the antennulae, in the male pleopods,
and in the maxilliped (see discussion above under Coperonus).
The
single small individual is assigned Lionectes species incertae sedis
until it can be examined and described more rully.
The distribution of Lionectes is limited to Antarctic seas, with
humicephalotus from the South Shetland Islands and the Weddell Sea,
ｾＮ＠
｡ｮ､ｾＮ＠
SPa
incertae sedis from eastern Antarctica.
Known members of
this genus are very small, so their restricted distribution may be
partially due to sampling artifacts.
Lionectes has not been round in
the relatively carefully sampled Atlantic Ocean, giving evidence that
this genus is not ｣ｯｳｭｰｬｩｴ｡ｮＮｉｾ･ｲｧｹＬ＠
species of Lionectes
co-occur with those of Coperonus at all the localities where Lionectes
has been found.
Coperonus, however, is much more broadly distributed.
82
Figure 2.11.
Lionectes humicephalotus new genus, new species.
holotype brooding female.
uropod.
A-O,
A, lateral view, with enlargement of
B, dorsal view, scale bar 1.0 mm.
0, cephalon dorsal view.
D-F, cephalon, paratype brooding female, bl 1.2 mm, lateral, frontal
oblique and anterior views respectively.
83
\
"'\ \
I
I
..Ｎｾ＠
Ｎｾ＠
:)
84
Lionectes humicephalotus new species
(Figures 2.11 - 2.14)
Holotype.--Brooding female, bl 1.2 mm, all limbs on right side except
pereopod I intact, USNM.
Paratypes.--3 brooding females, partially or completely dissected for
description, SIO.
Type-Locality.--Institute of Oceanography, Dalhousie (IODal) benthic
station 13, North of King George Island, South Shetland Islands, 61 0
18' S, 58 0 00' W, 282 m, collected with a small epibenthic sled on 7
February 1970 during Bedford Institute of Oceanography cruise
"Hudson 70."
Other Material.--Female, IODal 7; damaged female, 69Rankin 001AD;
damaged brooding female, 68Rankin 0055SBT.
SIO.
General Distribution.--South Shetland Islands to the Weddell Sea,
58.6-659 m.
Derivation of Name.--Humicephalotus means "provided with flat head."
Diagnosis.--See description.
There is insufficient information on the
species of this genus to allow a diagnosis at this time.
Description of Brooding Females Only.--Body Characters (fig. 2.11A-B):
Adult body length 1.1-1.4 (4 inds) mm, length 1.9-2.0 (4 inds) width.
85
Figure 2.12.
Lionectes humicephalotus new genus, new species,
paratype brooding female, 1.2
view.
Mm.
A, O-G, left mandible.
B, incisor process, right mandible.
lacinia mobilis, plan view.
F, palp, lateral view, setae
G, whole mandible, ventral view.
I, right maxilla.
0, incisor process and
D, molar process, posterior view.
posterior view of whole mandible.
omitted.
A, dorsal
J, right maxilliped.
H, left maxillula.
E,
86
,
Ｇｾ＠
I
(
\
,
I
87
Body setation (fig. 2.11B): Natasome with approximately 5 setae on
each ventrolateral margin; other dorsal surfaces with scattered fine
setae.
Cephalon (fig. 2.11C-F): Dorsal length 0.35 width, length 0.68 height,
width 0.67-0.70 (2 inds) width of body at pereonite 5.
Ventral margin
at posterior articulation of mandible lacking indentation or notch.
Antennula (fig. 2.11C): Length 0.16 body length, with 7 articles and 2
aesthetascs distally.
Article 1 medial length 0.94 width; medial lobe
with approximately 3-4 broom setae.
Articles 2 with broom setae.
Article 2 with 2 distal projections bearing broom setae: 1 dorsally
and 1 laterally.
Article 2 length (including dorsal projection) 0.58
article 1 medial lobe length.
Article 3 length 0.34 article 2 length.
Antenna (fig. 2.11A): Total length greater than 1.6 (2 inds) body
length (tip of flagellum broken).
Article 5 shorter and more robust
than article 6; article 5 length 0.58 article 6 length, 0.23 body
length.
Mandible (fig. 2.12A-G): Left mandible with 3 cusps on incisor
process; right mandible with large central cusp, smaller cusp on
either side, and 3 small denticles on dorsal margin.
Lacinia mobilis
only slightly narrower than left incisor process, with 3 cusps
extending to tip of incisor process.
members.
Spine row reduced, with 3
Molar process with thin cuticle, not calcified, distal end
with no circumgnathal denticles or large pointed cusp on ventral
margin; posterior margin with 1 flattened setulate seta; triturating
88
surfaoe without evident sensory pores.
mandibular body length.
Condyle length 0.35 (2 inds)
Palp seoond artiole length 0.36-0.38 (2 inds)
mandibular body length; distal artiole robust, strongly ourled.
Maxillula (fig. 2 .12H): Normally developed.
Inner endi te short and
rounded, laclcing large apioal seta, but with several smaller setae,
width 0.61 outer endite width.
Maxilla (fig. 2.121):
ｎｯｲｭｾｬｹ＠
developed.
Outer lobes approximately
same length as inner lobe.
Maxilliped (fig. 2.12J): Basis with 2 reoeptaouli and 3 fan setae
distally.
Endi te length 0.52 total basis length.
Palp artiole 2
width 1.9 endite width, lateral length 2.0 medial length.
artiole 3 lateral length 0.34 medial length.
Palp
Epipod oval, lateral
edge scalloped; length 0.88 basis length; length 1.5 width.
Coxa
elongate, subequal to basal seotion of basis.
Ambulatory Pereopods (fig. 2.11A, 2.13A):
Pereopods I-IV thin,
lightly setose; length-body length ratios 0.61, 0.92, 1.0, 1.2,
respeotively.
Bases I-IV length-body length ratios 0.17, 0.15, 0.17,
0.21, respeotively.
Natatory Pereopods (fig. 2.13C-E): Natapods heterogeneous in form:
pereopod V with very broad carpus and propodus, many natatory setae,
and rudimentary daotylus; pereopod VI with narrower oarpus and
propodus, many natatory setae, and long ourved daotylus; pereopod VII
resembling walking leg with narrow distal segments, approximately 4
natatory setae on ventral margin of oarpus only, propodus longer than
89
Figure 2.1).
Lionectes humicephalotus new genus, new species,
paratype brooding female, bl 1.2 mm.
A, left pereopod I.
B,
natasome, ventral oblique view, showing form of ventral surface and
relative sizes of pereopodal bases.
enlargement of dactylus.
0, right pereopod V with
D-E, left pereopods VI-VII.
90
91
carpus.
Pereopods V-VII increasing in length but becoming narrower
posteriorly; length-body length ratios 0.74, 0.79, 0.83, respectively.
Bases V-VII also increasing in length posteriorly; length-body length
ratios 0.17, 0.21, 0.23, respectively.
ratios 1.0, 1.4, 3.7, respectively.
Carpi V-VII length-width
Propodi V-VII length-width ratios
1.5, 2.5, 6.6, respectively; propodi V-VII length carpus length ratios
0.90, 0.84, 1.5, respectively.
Dactyli VI-VII long, curved; length-
propodus length ratios 0.90, 0.89, respectively.
Dactylus V
rUdimentary.
Male Pleopods I and II: unknown.
Female Pleopod II (fig. 2.14A-B): Keel narrow, rounded in lateral
view, without distinct apex or large setae, deepest in proximal half
of pleopod, distinctly set off from lateral fields.
Ventral surface
with only fine setae. Distolateral margins with approximately 10-12
long plumose setae on distal half of margins.
Length 1.3 width; depth
0.36 length.
Pleopod III (fig. 2.14D): Exopod distally truncate, longer than
endopod, with 3 long plumose setae, and 1 simple seta on distal tip.
Endopod with 3 distal plumose setae.
Uropod (fig. 2.11A, 2.14G): Protopod length 1.4 width; length 0.08
body length.
length.
Exopod 0.54 endopod length.
Endopod 0.68 protopod
Distal margin of protopod with approximately 6 whip setae.
92
Figure 2.14.
Lionectes humicephalotus new genus, new species,
paratype brooding female, b11.2.
A, ventral view of pleotelson.
B-C, pleopod II, lateral and posterior views.
III-V.
G, left uropod, lateral view.
D-F, left pleopods
93
E
F
). 0
94
Remarks.--Lionectes humicephalotus is currently known only from
females; 4 brooding females were collected at the type locality off
King George Island, and the other two localities yielded only damaged
females.
ｾＮ＠
sp. incertae sedis (Vanh8ffen, 1914) is also known from a
single female.
There are differences between the illustrations of
sp. incertae sedis and
ｾＮ＠
ｾＮ＠
humicepbalotus described here, but it is
uncertain whether the illustrations of the former species are accurate
in small details.
These include the lateral margin of pereonite 7
extending to the body margin, the longer uropodal exopod, and the
presence of an elongate dactyl on pereopod VII.
Other differences
might be developmental since Vanh8ffen's specimen was not brooding.
more detailed characterization of Lionectes must await the capture of
males.
A
95
Genus LIPOMERA Tattersall, 1905a
(Figures 2.15 - 2.24)
Type-Species.--Lipomera 1ame11ata Tattersall, 1905a.
Diagnosis.--Body dorsal surface without large vertical spines or
setae.
Cephalic anterior and lateral margin lightly calcified, in
frontal view semicircular; ventral margin folding into deep notch at
posterior articulation of mandible, articular margin protruding
laterally in dorsal view.
convex in dorsal view.
Rostrum nearly absent, vertex smoothly
Frons broadly rounded, almost flat, lacking
frontal arch, with distinct separation between antennulae.
C1ypeus
arched, narrow strip, medial part triangular in frontal view, apex
articulating directly to frons.
cephalon height.
Labrum high, height greater than half
Body deepest at pereonite 5.
Natasome triangular in
dorsal view; pereonites 5 and 6 large, dorsal articulations distinct •
.
Pereonite 7 reduced, fused to pereonite 6.
or coil.
Midgut with distinct bend
Antennula first article with no medial lobe and distinct
flattened lateral lobe; in females, antennula reduced to approximately
5 articles, male antennula not reduced.
Antennular scale absent.
Mandible with palp approximately same length as mandibular body; molar
process variously enlarged; condyle with posterior support ridge
extending to posterolateral corner of mandibular body.
Pereopodal
bases I-III and VI subequa1, basis V longest, basis IV intermediate in
length.
Pereopods V-VI natatory; pereopod VII tiny and rudimentary,
or completely absent.. Dactyli of pereopods V-VI long, thin, lengths
subequa1.
Female p1eopod II tip with short fused slit.
Uropod
96
lacking rami; protopod flattened, leaf-like.
Derivation of Name.--In the name Lipomera, Tattersall (1905a, 1905b)
seems to be referring to the lack of a well-developed seventh
ｰ･ｲｯｮｩｾ＠
in this genus bY' combining lipo-, a prefix meaning "to be
lacking," with
ｾＬ＠
a latinized form of the feminine Greek word meris
which means "a part."
Generic Remarks.--Tattersall (1905a) made this genus the type of a new
family, Lipomeridae, whereas the same author (1905b), in writing the
full description of Lipomera, placed it into the Munnopsidae, which
then included the current familY'-group Eurycopidae.
Neave (1939)
cites Tattersall (1905a), the report to the British Association for
the Advancement of Science, as the original publication of the genus.
Nierstrasz and Stekhoven (1930), Nordenstam (1933), and Hult (1941)
list (possiblY' erroneouslY') Tattersall (1905b) as actuallY' being
published in 1906, although Hansen (1916) who was activelY' working at
the time of publication, lists the date as 1905.
Tattersall's first
paper maY' possibly' have come out late in 1905, making some authors .
believe it was published in 1906.
Note that if Lipomera is placed
in the same familY' with Eurycope but separate from the Munnopsidae,
then the familY' must be called Lipomeridae because a familY'-level name
was not based on Eurycope until Hansen's (1916) Eurycopini.
Eurycopidae would be a junior synonym of Lipomerinae.
A better
resolution of this problem is the revised classification of the
munnopsoid taxa (see chapter 5).
97
Lipomera is easily separated from other ilyarachnoid eurycopids.
None of the other ilyarachnoid genera has a lamellar uropod that lacks
rami and covers the anal region of the pleotelson.
The cephalon of
Lipomera is also unique: a frons lacking a frontal arch, and with the
clypeus and labrum set low on the frons.
The uropodal and cephalic
characters are especially useful for separating Lipomera from the
somewhat similar new genus Mimocopelates.
Rudimentary or absent
seventh pereopods distinguish Lipomera from the new genera Coperonus,
Hapsidohedra, and Lionectes.
Lipomera must be divided into three new subgenera,
L. (Tetracope),
｡ｮ､ｾＮ＠
ｾＮ＠
(Lipomera),
(Paralipomera), because important
specializations identify groups of species within the genus but not
the genus a whole.
species,
ｾＮ＠
ＨｾＩＮ＠
Subgenus Lipomera contains the generic type-
lamellata, and consists of short and broad species
that have short heads, smooth dorsa without denticles on the anterior
margins, and rudimentary pereopods VII and pereonites 7.
Tetracope is similar
ｴｯｾＮ＠
Subgenus
(Lipomera) in body shape and retention of a
a rudimentary pereopod VII but differs in the following ways: the gut
is coiled or has an exaggerated bend (discussed below), pereonite 6 is
larger than pereonite 5, pereopods V and VI are similar in size, and
the uropods are narrow and pointed, not large and round.
Paralipomera is similar
ｴｯｾＮ＠
Subgenus
(Lipomera) in having only a modest bend
in the midgut, pereonite 5 and pereopod V larger than pereonite 6 and
pereopod VI, and having large round uropods, but its members have
longer and narrower bodies; longer, more robust heads; ornamented
dorsal surfaces with denticles on the anterior margins; and no seventh
98
pereopods or pereonites as adults.
Species ot Lipomera have curved, strongly bent, or coiled midguts
(tigure 2.21).
This is highly unusual in the Crustacea.
Few other
groups are known-to have coiled guts; CaIman (1909) mentioned only
two, a group ot Cladocera and a single genus ot Cumacea.
A curved or
coiled gut is a derived condition in this genus, because all ot the
other ilyarachnoid eurycopids, or munnopsoids more generally, have
straight guts (personal observations).
the bivalve
ｾ＠
In another invertebrate taxon,
protundorum, a coiled gut has been associated with an
adaptation to the tood poor conditions ot the deep sea (Allen and
Sanders, 1966).
The caeca ott the anterior portion ot the midgut are
unusually large in Lipomera, supporting this hypothesis.
There is no
certainty that improved digestion is the reason convoluted guts are
seen in Lipomera, although alternative hypotheses are not apparent at
this time.
Lipomera is currently known only trom the Atlantic Ocean: north,
south, and the Gult ot Mexico.
99
Figure 2.15. Lipolllera (Lipolllera) lamellata Tattersall, 1905a, new
subgenus.
A, holotype temale, dorsal view.
lateral views.
(1905b) •
C, rudimentary pereopod VII.
B, uropod, ventral and
Atter Tattersall
100
LIPOMERA New Subgenus
(Figures 2.15, 2.21B)
Diagnosis.--Dorsal surface of body with thin, smooth cuticle; anterior
margins of pereonites without denticles.
Pereonite V longer than pereonite VI.
sclerotized and strengthened.
shorter than pereopod V.
Cephalon not indurate.
Mandible not heavily
Midgut curved, 'not coiled.
Pereopod VI
Pereopod VII present but rudimentary.
Composition.--Monotypic: Lipomera (Lipomera) lamellata Tattersall,
1905a.
Lipomera (Lipomera) lamellata Tattersall, 1905a
(Figure 2.15)
Types.--Eleven syntype individuals from 60 miles West of Aohill Head,
Ireland, August 1901, 199 fathoms (364 meters), 53 0 58' N, 120 16' W.
Length of (figured?) adult female reported as 1.25 mm.
Complete
description by Tattersall (1905b, pp. 32-35, pl. viii, locality data
on p. 75).
description.
No holotype or depository designated in original or later
Types not examined.
Distribution.--Known only from the type-locality off the western coast
of central Ireland at a depth of 364 meters.
Diagnosis.--Anterior margins of dorsal segments without denticles.
Cephalon medial length approximately one third cephalon width.
Body
dorsal surfaces smooth, with few setae; anterolateral corners of
pereonites and pleotelson with long setae.
Male antennula with 11-13
102
articles.
Pleotelson wider than long, sides in dorsal view smoothly
rounded; distal tip in dorsal view broadly pointed, almost rounded.
Male pleopod I tip narrow, acutely pointed.
Uropod posterior margin
straight.
Remarks.--Lipomera (Lipomera) lamellata has not been collected since
its original capture in 1901.
This may be due to its inhabiting a
depth that is too shallow for many deep sea studies, and too deep for
most shallow water benthic work.
Another undescribed species of
ｾＮ＠
(Lipomera) occurs off Walvis Bay, Africa, at a depth of approximately
200 m.
ｾＮ＠
ＨｾＮＩ＠
lamellata is different from this other species in the
collection b.f its larger size (the undescribed species has 0.8 mm long
adults!), and by its rounded pleotelson tip, pointed male pleopod I,
and narrower cephalic vertex.
103
PARALIPOMERA New Subgenus
(Figures 2.16 -2.19)
Diagnosis.--Dorsal surface partially indurate, with denticles on
anterior margins.
pereonite VI.
Cephalon indurate.
Mandible heavily sclerotized and strengthened.
curved, not coiled.
VII absent.
Pereonite V longer than
Pereopod VI shorter than pereopod V.
Midgut
Pereopod
Uropod large, leaf-like, round, extending beyond distal
tip of pleotelson.
Derivation of Name.--Paralipomera (Greek, feminine) means "next to
Lipomera."
Lipomera (Paralipomera) knorrae new species
(Figures 2.16 - 2.19)
Holotype.--Copulatory male, bl 1.2 mm, USNM.
Paratypes.--Brooding female, bl 1.5 mm, USNM.
Copulatory male, bl 1.2
mm, ZMUC.
Ten individuals, some
Brooding female, bl 1.4 mm, MNHNP.
dissected for description, SIO.
Type-Locality.--WHOI 340, 380 14.4-17.6' N, 700 20.3-22.8' W, 32643256 m, collected with an epibenthic sled, 3 December 1973, R/V Knorr
cruise no. 35, leg 2.
Distribution.--Known only from type-locality, Western Atlantic on the
Gay Head-Bermuda transect, 3256-3264 m.
104
Figure 2.16.
species.
mm.
a,
Lipomera (Paralipomera) morrae new subgenus, new
A-B, holotype male, dorsal and lateral views, scale bar 1.0
paratype preparatory female, dorsal view, with detail of
cuticular sculpturing on pleotelson; p6 - pereonite 6, p7 - pereonite
7.
D-G, cephalon, antennula and antenna removed to show frons,
paratype male anterior body fragment: D, frontal oblique view; E,
dorsal view; F, anterior view; G, lateral view.
105
106
Derivation of Bame.--This species of Lipomera is named knorrae after
the R/V Knorr of the Woods Hole Oceanographic Institution.
Diagnosis.--Anterior margins of cephalon and anterior 5 pereonites
with numerous small spines.
cephalon width.
Cephalon medial length approximately half
Body dorsal surfaces with fine cuticular
ornamentation and scattered fine setae; anterolateral corners of
pereonites and pleotelson with small fine setae only.
Pleotelson
longer than wide, sides in dorsal view with distinct angle at
insertions of uropods; distal tip in dorsal view acutely rounded.
Male antennula with 18-20 articles.
acutely pointed.
Male pleopod I tip narrow,
Uropod posterior margin convexly curved.
Description.--Body Characters (fig. 2.16A-C):
In adult males, body
length 1.2-1.5 mm (4 inds); body length 2.6-2.7 width (4 inds).
In
adult females, body length 1.4-1.5 mm (4 inds); body length 2.6-2.8
width (4 inds).
Cephalon (fig. 2.16D-G):
(8 inds).
Width 0.79 body width, ratio range 0.72-0.83
Medial dorsal length 0.54 width; length 0.72 height.
Ventral margin at posterior articulation of mandible with distinct
indentation or notch.
Antennula (fig. 2.16A-B, 2.17A-B): Highly sexually dimorphic: in
males, length 0.45-0.46 body length; in females, 0.16.
Male
antennula with 15-17 articles and approximately 8 aesthetascs
distally; female antennula with 5 articles and 1 aesthetasc distally.
Article 1 not sexually dimorphic, medial length 0.77 width in female;
107
Figure 2.17.
species.
Lipomera (Paralipomera) knorrae new subgenus, new
A, right antennula, paratype female, bl 1.4 m.
paratype male, bl 1.5
0.
B, right, antennula and antenna, basal
segments, cuticular ridges shown, lateral view.
mandible.
view.
0, dorsal view.
B-J,
0, E-G, left
D, incisor process, right mandible, plan
E, incisor process and lacinia mobilis, plan view.
F, distal
part of' mandibular body, ventral view; dotted lines show thickness of
sclerotization.
I, lef't maxilla.
G, molar process, medial view.
H, left maxillula.
J, maxilliped, with enlargement of distal tip,
lateral fan seta shown separately.
108
ｎｾ＠
'D·
E
A
F
G
B
,.'
H
I
109
medial side of both sexes with no setae; lateral lobe with single
broom seta.
Articles 2 and 4 with large broom setae.
Article 2
subequal to or longer than article 1 lateral lobe in both sexes,
article 2 broader in males than in females.
Article 3 subequal to or
slightly shorter than article 2 in males, article 3 length 0.43
article 2 length in females.
Mandible (fig. 2.17C-G): Heavily sclerotized and modified.
Left
incisor process with 3 short, broad cusps; right incisor process with
only 2 low, broad cusps.
Lacinia mobilis reduced, narrower than
incisor process, with 3 low cusps. Left spine row with 3 members; 4 on
right side.
Molar process distal surface convexly rounded, with no
circumgnathal denticles and with single rounded cusp on posterior
margin adjacent to 2 flattened setulate setae; triturating surface
with approximately 2 sensory pores.
Condyle elongate and curved,
length of curved lateral margin 0.67 mandibular body length.
Palp
second article length 0.52 mandibular body length; palp distal article
slightly curved and thin.
Maxillula (fig. 2.17H): Normally developed.
Inner endite width 0.41
outer endite width.
Maxilla (fig. 2.17I): Normally developed.
inner lobe.
Outer lobes shorter than
110
Figure 2.18.
species.
Lipomera (Paralipomera) knorrae new subgenus, new
A, right pereopod I, male holotype, bl 1.2 mm.
B-G, left
pereopods I-VI, paratype male, bl 1.5 mm, pereopod II with
enlargements of 2 joints and distal tip.
scale of A and G-F.
B-E at half
111
112
Maxilliped (fig. 2.17J): Basis with 2 receptaculi.
Proximal part of
basis very broad, with semicircular lateral margin, maximum width
nearly 3 times endite width.
Endite with 4 fan setae distally, medial
fan seta more robust, with rewer and broader branches than 3 lateral
fan setae; distomedial corner also with short bifurcate seta medial to
robust fan seta.
Endite length 0.41 total basis length.
Palp article
2 width 1.8 endite width, lateral length 2.2 medial length.
article 3 lateral length 0.33 medial length.
Palp
Epipod medial margin
straight; distal tip rounded, with single seta; length 0.62 basis
length; length 1.8 width.
Ambulatory Pereopods (fig. 2.18A-E):
Pereopods I-IV similar, thin,
without large spine-like setae; length-body length ratios 0.64, 0.95,
0.93, 0.95, respectively.
Pereopod I not sexually dimorphic.
Bases
I-IV length-body length ratios 0.18, 0.18, 0.18, 0.19, respectively.
Bases II-IV with group of broom setae on anterior midpoint.
Natatory Pereopods (fig. 2.18F-G): Natapods heterogeneous in form:
pereopod V larger that pereopod VI, pereopod VII absent.
length-body length ratios 0.66 and 0.54, respectively.
Pereopod
Bases V-VI
length-body length ratios 0.21 and 0.17, respectively; both segments
with long row of simple or whip setae.
with distal group of broom setae.
and 1.6, respectively.
respectively.
Basis V thickened distally,
Carpi V-VI length-width ratios 1.3
Propodi V-VI length-width ratios 1.7 and 2.1,
Dactyli V-VI long, thin, with marginal fringe of fine
setae; length ratios with respective propodi both 0.71.
Unguis V
claw-like, long, and curved; unguis VI similar but very short.
113
Male Pleopod I (fig. 2.19A-B).
Fused pleopod pair widest at
insertion, tapering to distal tip.
orifice 0.43 total width.
distal tip.
Length 2.7 width; width at dorsal
Dorsal orifice 0.24 total length from
Distal tips flattened in lateral view, tapering and
bluntly pointed in ventral view, without distinct outer lobes.
Setae
only on distal tips: each with distodorsal groups of setae and setal
row adjacent to midline.
Male Pleopod II (fig. 2.19A,C-D):
Protopod widest at insertion,
tapering posteriorly to curved post-exopodal projection; length 2.8
width.
Distal tip of protopod with medial groove enclosing exopod;
groove lined with dense group of long fine setae.
Distal tip of
protopod with lateral row of thick-bodied plumose setae. Stylet length
0.68 protopod length; sperm duct opening at midpoint of stylet; stylet
inserting 0.39 length of protopod from distal tip.
Exopod small,
covered by ventral surface of protopod, with tuft of fine setae.
Female Pleopod II (fig. 2.19H-J): Operculum triangular in ventral
view, with tapering distal tip.
Length 1.58 width; depth 0.39 length.
Dorsal surface with few scattered fine setae; distal tip with
approximately 10 plumose setae.
Keel thick, deep, apex below
posterior insertion; pleopod keel distinct from thick lateral fields.
Pleopod III (fig. 2.19E): Exopod broad, width two thirds that of
endopod; distal tip nearly extending as far as endopod; tip with with
2 long plumose setae, and 1 simple seta.
setae.
Endopod with 3 long plumose
114
Figure 2.19.
species.
Lipomera {Paralipomera} knorrae new subgenus, new
A-G, K, paratype male, bl 1.5 mm.
ot natasome, showing torm ot ventral surtace.
enlargement ot distal tip.
A, ventral oblique view
B, pleopod I with
C-D, lett pleopod II, whole limb and
enlargement ot distal portion, showing endopod and exopod through
ventral cuticle.
E-G, lett pleopods III-V.
and posterior views, respectively_
H-J, ventral, lateral,
K, right uropod, lateral view.
115
t
f
K
116
Uropod (fig. 2.19K): Protopod broad, rounded, and flattened, with
dorsal fold having two plumose setae medially.
1.49 width; medial length 0.12 body length.
Protopod dorsal length
Distal margin of protopod
with small group of simple setae and broom setae.
Remarks.--Lipomera (Paralipomera) knorrae oan be distinguished from
other 3 undesoribed speoies of its subgenus by the presence of spines
on the anterior margins of the cephalon and pereonites, b,y the shape
of the pleotelson, and its relative paucity of fine setae on the
dorsal surface.
genus Lipgmera.
This species is the deepest occurring member of the
The 3 undescribed species of the subgenus
Paralipomera are found at slope depths off Afrioa, Brazil, and the
southern United States in the Gulf of Mexioo.
117
TETRACOPE New Subgenus
(Figures 2.20 - 2.24)
Diagnosis.--Dorsal surface of body with thin, smooth cuticle; anterior
margins without denticles.
shorter pereonite VI.
strengthened.
Cephalon not indurate.
Pereonite V
Mandible not heavily sclerotized and
Midgut coiled, or with exaggerated bend (fig. 2.21A).
Pereopod VI approximately same length as pereopod V.
present but rudimentary (2.241).
Pereopod VII
Uropod narrow, pointed, not
extending beyond distal tip of pleotelson, with 2 segments in some
species.
Derivation of Name.--Tetracope (Greek, feminine), which translates as
"four oars," refers to the two pairs of similar natapods on pereonites
5 and 6.
Lipomera (Tetracope) curvintestinata new species
(Figures 2.20 - 2.24)
Holotype.--Copulatory male, bl 0.74 mm, only a few limbs broken off,
USNM.
Paratypes.--Preparatory female, bl 0.87 mm, USNM; 50 specimens, some
dissected for description, SIO.
Type-Locality.--WHOI 209, 390 47.6-46.0' N, 700 49.9-49.5' W, 15011693 m, collected on the Gay Head-Bermuda Transect during R/V Chain
cruise no. 88, 22 February 1969.
118
Figure 2.20.
species.
Lipomera (Tetracope) curvintestinata new subgenus, new
A, 0, holotype male, lateral and dorsal views.
paratype preparatory female, lateral and dorsal views.
1.0 mm.
B, D,
Scale bar
119
Figure 2.21.
A, Lipomera (Tetraoope) ourvintestinata new subgenus,
new speoies, paratype brooding female, bl 0.9 mm, view of alimentary
oanal and digestive oaeoi through ventral body surfaoe.
B, Lipomera
(Lipomera) sp., male, bl 0.8 mm, WHO! 180, oblique view through
ventral cutiole showing alimentary oanal and digestive oaeoa through
ventral body surfaoe.
121
122
Other Material.--WHOI 73,4 brooding females.
females, 1 male.
female.
WHOI 210, 2 brooding
BAT M1-13-1-7, juvenile female.
BAT S1-3-1-3,
BAT S2-3-2-(1-9}, juvenile male.
General Distribution.--Slope depths off East Coast of U.S.A.,
1500-2064 m.
Derivation of Name.--Curvintestinata means "provided with curved
intestine," referring to the coiled gut of this species.
Diagnosis.--Cephalon medial length approximately one half cephalon
width; cephalon narrower than pereonite 1; frons rounded in dorsal
view.
Body dorsal surfaces with few fine setae and no pigmentation.
Pleotelson length subequal to or shorter than combined length of
pereonites 5-6.
Midgut with 1 complete coil.
Female antennular
article 3 length approximately 2 times length of article 4.
male antennula with 14-15 articles.
Adult
Pleotelson sides almost straight,
terminating with rounded point in dorsal view; in lateral view dorsal
surface of pleotelson only weakly curving.
rounded.
Male pleopod I tip narrow,
Keel of female pleopod II flattened anteriorly, appearing as
straight line in lateral view, with angular transition at
anteroventral apex.
Uropodal protopod and distal ramus fused, with no
apparent suture (compare fig. 2.24 M and O).
Description.--Body Characters (fig. 2.20A-D): Adult body length 0.74
mm (2 inds) in males, 0.89-0.90 mm (3 inds) in females; length 1.9-2.1
(4 inds) width, anterior segments subject to compression.
Body form
not sexually dimorphic, except females often widest at pereonite 4.
123
Cephalon (fig. 2.22A-D): Dorsal length 0.38 width, length 0.54 height.
Ventral margin at posterior articulation of mandible with deep fold
projecting laterally.
Antennula (fig. 2. 23A-0) : Strongly sexually dimorphic, being much more
robust, longer, and with more articles and aesthetascs in male than in
female; both sexes with geniculation between articles 2 and 3.
In
males length 0.43-0.45 (2 inds) body length; in females, 0.20-0.22 (3
inds).
Male antennula with 14-15 articles and approximately 10
aesthetascs distally; female antennula with 6 (3 inds) articles and 1
aesthetasc distally.
Article 1 medial and lateral lobes pointed
distally, with broom setae only; medial length 0.84 width in male,
0.97 in female; medial lobe of both sexes with 2 broom setae.
Articles 2 and 4 with broom setae.
Article 2 length 3.6 article 1
medial lobe length in females, length 5.8 medial lobe length in males.
Article 3 length 0.58 article 2 length in female, 0.59 in male.
Mandible (fig. 2. 22E-N) : Not greatly modified: some reduction in molar
process setation and denticles, condyle large, but not heavily
calcified.
Both mandibles with 3 distinct cusps on incisor processes.
Lacinia mobilis normal size, extending to tip of incisor process,
width approximately three quarters width of incisor process, with 3
large cusps and 3 small cusps dorsally.
members, right spine row with 5.
Left spine row with 4
Molar process posterodistal edge
with gnathal plate having 3 sharp denticles and 2 flattened setulate
Figure 2.22.
Lipomera (Tetracope) curvintestinata new subgenus, new
species, paratype male, bl 0.74 mm.
A-D, cephalon, antennula and
antenna removed to show frons: lateral, frontal oblique, anterior,
dorsal views, respectively.
E, ventral oblique view of cephalon and
mandible, showing articulation; f - mandibular condyle articulating
with cephalic fossa, m - left mandible without palp, p - posterior
articulation between .cephalon and mandible.
F, dorsal view.
G, palp, lateral view.
mandible, ventral and plan views.
F-G, J-N, left mandible.
H-I, incisor process, right
J-K, incisor process, lacinia
mobilis, and spine row, lateral and plan views.
condyle, posteromedial view.
anterior views.
L, molar process and
M-N, molar process, posterior and
125
I
I
I
I
I
I
I
\
\
\
\
\
r4
.,
, ..
,1t
ｾＮ＠
H .
,
I
...
K
M
' ''
I
rn
()
!
ｾ＠
:
, '
::-:
,
I
,,
I
,
\
'
.fh\
N
126
setae; triturating surface with no visible sensory pores.
Cond7le
longer than molar process, distinct from posterior support ridge;
length 0.31 mandibular bod7 length.
Palp second article length 0.51
mandibular bod7 length; distal article not strong17 curved.
Maxillula (fig. 2.23E): Normal17 developed.
Inner endite width 0.45
outer endite width.
Maxilla (fig. 2.23F): Normal17 developed.
Outer lobes approximate17
same length as inner lobe.
Maxilliped (fig. 2.23G): Basis with 2 receptaculi and 3 fan setae
distal17; proximal part of basis not expanded, lateral edge broadl7
rounded, almost straight.
Endite length 0.57 total basis length.
Palp article 2 width 0.5 endite width, lateral length 2.0 medial
length.
Palp article 3 lateral length 0.31 medial length.
Epipod
broadl7 curved on medial margin, strong17 curved lateral17, with
fringe of fine setae distolateral17; length 0.84 basis length; length
1.4 width.
Ambulatory Pereopods (fig. 2.20A, 2.23H):
Pereopods II-IV with sparse
row of thin setae on dorsal and ventral margins of carpus and
propodus, pereopod I with few setae; length-bod7 length ratios 0.90,
1.18, 1.23, 1.32, respective17.
Pereopod I not sexuall7 dimorphic.
Bases I-IV length-bod7 length ratios 0.25, 0.26, 0.28, 0.28,
respective17.
Bases II-IV with few setae.
127
Figure 2.23.
species.
Lipomera (Tetracope) curvintestinata new subgenus, new
A, left antennula, paratype preparatory female, bl 0.84.
B-J, paratype male, bl 0.74 mm.
B-C, left antennula, lateral of whole
limb and dorsal view of proximal articles.
maxillula.
D, paragnaths.
F, left maxilla. 'G, left maxilliped.
I-J, right pereopods V-VI.
E, left
H, left pereopod I.
128
o
'. ......... ｾＢＬ＠
...
129
Natatory Pereopods (fig. 2.23I-J, 2.24A): Natapods V-VI similar in
form, with broad carpi and propodi; pereopod VII present only as tiny,
rudimentary 2 or 3 segmented appendage inserting medial to posterior
edge of coxae VI.
respectively.
Pereopod V-VI length-body length ratios 0.93, 0.89,
Bases V-VI length-body length ratios 0.26, 0.24,
respectively; basis V with distal broadened area having group of broom
setae.
Carpi V-VI length-width ratios 1.3, 1.5, respectively.
Propodi V-VI length 1.9 width.
Dactyli V-VI short, but not
rudimentary; length of both dactyli 0.29 propodi.
Unguis shaped like
seta, with accessory seta.
Male Pleopod I (fig. 2.24A,E-F).
Fused pleopod pair widest just
distal to rounded proximal margin., afterwards triangular, with almost
linear lateral margins and narrow distal tip.
dorsal bend, enclosing elongate penes.
dorsal orifice 0.32 pleopod width.
Proximal funnel with
Length 2.9 width; width at
Dorsal orifice 0.14 total length
from distal tip. Distal tips collectively semicircular in ventral
view; outer lobes not expressed.
Pleopod with few setae, each distal
tip with 3 simple setae in adult male, 2 in juvenile male.
Male Pleopod II (fig. 2.24A-D):
Protopod triangular in ventral view,
deep and rounded in lateral view; dorsolateral margin curled medially;
distal tip pointed; length 1.8 width; 2 plumose setae on distolateral
margin.
Stylet thin, length 0.43 protopod length; sperm duct opening
0.42 total stylet length from distal tip; stylet inserting 0.43 length
of protopod from distal tip.
setae.
Exopod small, rounded, with few fine
130
Figure 2.24.
species.
Lipomera (Tetracope) curvintestinata new subgenus, new
A-F, J-N', paratype male, bl 0.74 mm.
preparatory female, bl 0.84 mm.
G-I, paratype
A, pleotelson and pereonites 6-7,
ventral view, rudimentary pereopod VII indicated (PVII).
II, lateral and ventral view.
B-C, pleopod
D, pleopod II distal tip, medial view.
E-F, pleopod I, ventral and lateral view.
posterior, lateral, and ventral views.
G-I, female pleopod II,
J-L, right pleopods III-V.
N, right uropod, lateral and ventral views.
0, uropods, Lipomera
(Tetracope) sp., brooding female, bl 1.1 mm, WHOI 119.
M-
131
;:: ....., \...
"
I
' !,
JI
,
I
,,
,
..:
\
:'
,
\
,j
....,,
""
.'
E
"
'.
'.
I
,,
"
::
Ｖｾ＠
N
.'
132
Female Pleopod II (fig. 2.24G-I): Keel deep, acute in posterior view,
apex near anterior margin, sloping posteriorly and laterally to curled
under lateral fields.
Dorsal surface with few fine setae;
distolateral margins with 2 plumose setae on distolateral margin.
Length 1.3 width; depth 0.48 length.
Pleopod III (fig. 2.241): Exopod distally rounded, longer and narrower
than endopod, with 2 long plumose setae, and 1 simple seta on distal
,tip.
Endopod quadrate, with 3 distal plumose setae.
Uropod (fig. 2.24M-N): Protopod and endopod completely fused; exopod
absent.
Uropodal length 4.3 width; length 0.11 body length.
Dorsomedial margin with 1 long seta; row of broom setae on
distolateral surface.
Remarks.--Lipomera (Tetracope) curvintestinata was the first isopod
species I found with a complete coil in the midgut.
A survey of all
the ilyarachnoid eurycopids revealed that this condition was confined
to the genus Lipomera, and reached the most complex development in
this species and another undescribed species from Norway.
Other
species of Lipomera generally have a distinct bend in the gut, but not
coiled, similar
ｴｯｾＮ＠
(Lipomera) sp. (undescribed, see fig. 2.20B).
Another undescribed species of the subgenus Tetracope
demonstrates that the broad uropods of all members of the genus
Lipomera are made up of the fused protopod and endopod.
The setal
ｾＮ＠
homologies are distinctive (see fig. 2.24 M, 2.240, and 2.19K).
(I.) curvintestinata ｡ｮ､ｾＮ＠
Both
(!.) sp. have a long thin dorsal seta,
133
a distal group of broom setae, and a pair of small curled setae on the
lateral proximal margin.
In
1. (!.)
clearly divided into two sections.
sp., however, the uropodis
Because the exopod is small or
lost in most munnopsoids, the large distal section is the uropodal
endopod.
Also the exopodnever has broom setae on the distal tip, and
the endopod does.
The setal homologies may be extended to the other
members of Lipomera,
1.
(Paralipomera) knorrae for example. In this
latter species the uropod is a single segment and leaf-like.
The
distal tip has the same group of broom setae seen in species of the
subgenus Tetracope, as well as the large thin seta on the dorsal
margin of the uropod.
- -
In L. (T.) sp., the large seta is on the distal
edge of the protopod and the broom setae are on the tip of the
endopod.
- -
Therefore, the thin uropod L. (T.) curvintestinata and the
broad uropod of
1. (f.)
knorrae must consist of the fused segments of
the protopod and the endopod.
-L. (T.)
-
curvintestinata may be identified by a lack of pigment on
the dorsal surfaces (which the species from Norway has), by a cephalon
narrower than the first pereonite, and by a non-segmented uropod.
The
form of the body segments and the antennulae may be useful indicators
of species differences as well.
134
MIMOCOPELATES New Genus
,
(Figures 2.25 - 2.32)
Type-Species.--Mimocopelates longipes new species.
Generic Diagnosis.--Dorsal surface smooth, without spines.
absent.
Rostrum
Frons with triangular, flattened frontal arch adjacent to
clypeal attachment; frontal arch angular in frontal view.
Clypeus
medial section rounded in frontal view; dorsal apex higher than
articulation with frons, lower than apex of frontal arch.
anteriorly rounded.
Labrum
Pereonites 5-7 fused ventrally but with distinct
sutures dorsally; pereonite 5 largest; pereonite 7 dorsally reduced to
thin strip.
Ventral surface of natasome enlarged at pereonite 5,
compressed posteriorly at pereonite 6; pereonite 7 absent ventrally;
natasome deepest at large ventromedial hump between insertions of
pereopods V.
Antennular article 1 with short or undeveloped medial
lobes, lateral lobes dorsoventrally flattened, shorter than article 2.
Antennal scale absent.
Mandible modified: molar process distally
convex and heavily sclerotized, with reduced or absent circumgnathal
armature; support ridge
･ｾｴｮ､ｩｧ＠
from posterior edge of condyle to
posterolateral corner of mandibular body, appearing as separate
articular process from body of mandible; palp slender, shorter than
mandibular body.
Pereopod VII absent in adults.
Merus of natatory
pereopod V greatly elongated, much longer than basis. Dactylus of
pereopod V tiny, dactylus of pereopod VI long and thin.
Pereopodal
bases I-IV subequal, all longer than natapodal bases V-VI; basis V
shortest and stoutest, basis VI longer and less stout.
Uropod short
135
and somewhat flattened, recessed into posteroventral margin of
pleotelson; exopod tiny, reduced to small button, or completely
absent; endopod longer than protopod.
Derivation of Name.--Mimocopelates (Greek, masculine) means an
"imitator of a rower," a combination derived from the nouns mimus, "an
imitator," and copelates, "a rower."
Generic Remarks.--Mimocopelates is remarkable because pereopod VII is
completely absent, and pereopod VI is considerably reduced compared to
pereopod V.
If this trend were extrapolated, one would predict that
somewhere in the deep-sea an eurycopid exists or will exist (via
continued evolution) that lacks both pereopods VI and VII.
Increased
reliance on pereopod V for swimming is indicated by the enlarged
musculature in pereopod V, a more robust coxa and basis than is seen
in most eurycopids, and increase in the length of the limb segments,
ischium and merus, which extend the carpal and propodal paddles from
the body.
The elongation of the merus of pereopod V is unknown in any
other munnopsoid and, is, therefore, a useful autapomorphy.
In addition to the form of the natatory pereopods and pereonites,
the reduced uropods with tiny or absent exopods uniquely define this
genus.
by
ｾ＠
Mimocopelates contains two distinctive groups: one represented
longipes n.sp., and the other by M. anchibraziliensis nAsp.
Because these two species are so dissimilar in cephalic size and many
other characters, I once believed they should be separate genera.
However, the characters mentioned above outweigh these considerations,
and some of the specialized features that distinguish the two species,
136
such as the size ot the head, are known to vary wi thin the same genus
ot munnopsoid.
For example, compare the cephalic and mandibular
development ot Eurycope iphthima Wilson, 1981 and
ｾ＠
juvenalis Wilson,
1983.
Species ot the Mimocopelates longipes group are all similar to
each other, although several characters may be usetul tor
discriminating them.
These are the shape ot the vertex and the
interantennular distance, the length ot the endopod compared to the
width ot the protopod, and the shape ot the male pleopod I tip and the
number ot setae on it.
Mimocopelates, like most deep-sea asellote genera, may be
cosmopolitan: it has been tound in the North, Equatorial, and South
Atlantic.
In addition, D.E. Hurley, New Zealand Oceanographic
Institute, and R. Lincoln, British Museum (Natural History), have
collected specimens ot this genus trom bathyal depths ott New Zealand.
The latter specimens belong to an undescribed species that will be the
subject ot a tuture paper in which the munnopsoids trom New Zealand
will be described.
137
Figure 2.25.
Mimocopelates longipes new genus, new species.
holotype male, lateral and dorsal vie.ws, scale bar 1.0 mm.
view, paratype preparatory female.
A-B,
0, dorsal
D, ventral oblique view of
natasome, showing form of ventral surface and comparative sizes of
pereopodal bases, paratype preparatory female, bl 1.9 mm.
1,38
c
139
Mimocopelates longipes new species
(Figures 2.25 - 2.29)
Holotype.--Copulatory male, bl 2.1 mm, distal parts of antennulae,
antennae, and pereopods I-IV broken off.
Paratypes.--Preparatory female, bl 2.2 mm, USNM; brooding female and
copulatory male, bl 2.2., 1.9 respectively, ZMUC; brooding female, bl
2.2 mm, MNHNP; 20 individuals, some fragmentary or dissected for
description, SIO.
Type-Locality.--WHOI 321 500 12.3' N, 130 35.8' W, 2890-2868 m,
collected on 20 August 1972 during R/V Chain cruise no. 106.
Other Material.--A11 specimens in SIO: WHOI F1, 1 ind.; WHOI 64, 1
ind.; WHOI 66, 1 ind.; WHOI 73, 12 ind.; WHOI 85, 1 ind.; WHOI 103, 1
ind.; WHOI 128, 3 ind.; WHOI 131, 8 ind.; WHOI 156, 2 ind.; WHOI 209,
6 ind.; WHOI 210,2 ind.; WHOI 326, 2 ind.; WHOI 328, 6 ind.; WHOI 330,
1 ind.; INCAL DS13, 1 ind.; INCAL 0804, 1 indo
General Distribution.--Eastern and western North Atlantic from 50 0 to
equator, 1254-4822 m.
Derivation of Name.--Longipes (Latin) means "long-footed," referring
to the elongate natatory fifth pereopods.
Diagnosis.--Cephalon not enlarged, narrower than pereonite 1,
anteriorly sloping.
Cephalic vertex without distinct line separating
frons from cephalic dorsal surface.
Cephalic frontal arch sloping in
lateral view; distinctly anterior to vertex in dorsal view.
Ventral
140
margin of cephalon at posterolateral articulation of mandible with
deep, heavily sclerotized indentation or notch.
Interantennular
distance broad: distance between medial corners of antennular
insertions 0.17-0.20 (2 inds) cephalon width, not sexually dimorphic.
Maxillipedal epipod distally rounded.
Male pleopod I distal tip with
3 large and 1 small fat-based setae ventrally, 4 setae at distoventral
midline, and 4 setae in dorsolateral group.
Uropodal endopod length
2.8-3.0 width, length as long as or slightly shorter than protopod
width; protopod distomedial corner projecting acutely; exopod present
as tiny button.
Description.--Body Characters (fig. 2.25A-C): Adult body length 1.92.2 mm (6 inds), females as large as or larger than males; body length
2.1-2.3 width (6 inds).
Pleotelson sexually dimorphic: in male,
longer and more inflated compared to female; male pleotelson length
0.38 body length, in female, 0.34.
Body setation (fig. 2.25A-C): Natasome with many fine setae on dorsal
surfaces; ambulosome and cephalon with scattered fine setae.
Cephalon (fig. 2.26A-C): Dorsal length 0.43 width, height 1.3 width.
Antennula (fig. 2.27E-F): Flagellum and more proximal segments broken
in all specimens examined.
Male antennula more robust and possibly
longer than female antennulaj male flagellum with many thick and short
articles.
Aesthetascs unknown.
Article 1 medial length 0.49 width in
male, 0.51 in female; width 0.35-0.38 cephalon width in males (2
inds); 0.26-0.28 in females (3 inds); medial edge of both sexes with
Figure 2.26.
Mimocopelates longipes new genus, new species, paratype
female, bl 1.9 mm.
A-C, cephalon, antennula and antenna removed to
show frons, views: frontal oblique, anterior, lateral, respectively.
D-I, I, left mandible.
F, ventral view.
D, dorsal view.
E, palp, distal segment.
H, molar process and condyle, anteromedial view.
incisor process and lacinia mobilis, plan view.
right mandible, plan view.
J, incisor process,
I, molar process, anterior view.
I,
142
143
2-3 broom setae.
Articles 2 and 4 with broom setae.
Articles 2 and 3
sexually dimorphic, being broader and more robust in males than in
females.
Article 2 with distolateral projection having broom setae on
2 points; article 2 length subequal to article 1 medial length in
female, length 0.92 medial length in male; distal width 0.88 length in
female, 1.14 in male.
Article 3 length 0.75 article 2 length in male,
0.73 in female.
Mandible (fig. 2.26D-K): Both mandibles with 1 small dorsal and 3
large teeth on incisor processes.
Lacinia mobilis large, extending to
tip incisor process, with 6 teeth, ventral tooth largest.
rows with 5 members each.
Both spine
Molar process distal end with 5-6 low
denticles on posterior margin, and low broad cusp on ventral margin;
posterior margin with 3 flattened setulate setae; smooth, convexly
rounded triturating surface projecting beyond level of circumgnathal
armature; sensory pores not observed on triturating surface.
Condyle
roughly same length as molar process, thickened, heavily sclerotized;
length 0.29 mandibular body length.
Palp second article length 0.52
mandibular body length; distal article strongly curved, inner part of
curve well armed with pointed setulate setae.
Maxillula (fig. 2.27B): Normally developed.
outer endite width.
Inner endite width 0.64
Distal tip of inner lobe with several very fine,
equally bifid setae.
Maxilla (fig. 2.270): Normally developed.
to inner lobe.
Outer lobe length subequal
Central lobe shorter than inner lobe.
144
Figure 2.27.
Mlmocopelates longipes new genus, new species.
H, paratype preparatory female, bl 1.9 mm.
A, paragnaths.
maxillula, with enlargement of distal tip of inner endite.
maxilla.
A-E,
B, left
0, right
D, left maxilliped with enlargement of endite distal tip.
E, proximal articles of antennula.
antennula, paratype male, bl 2.1 mm.
F, proximal articles of the
G, right uropod, proximal parts
seen through cuticle, in situ, holotype male, bl. 2.1 mm.
uropod, medial view.
H, left
145
146
Maxilliped (fig. 2.27D): Basis with 3 receptaculi medially and 6 fan
setae distally; medial fan seta more robust, with fewer and. broader
branches than 5 lateral fan setae; lateral fan setae bifid, with deep
separation between sides.
Endite length 0.56 total basis length.
Palp article 2 width 1.5 endite width, lateral length 1.5 medial
length.
Palp article 3 lateral length 0.27 medial length.
Epipod
short, oval, -with fine cuticular combs around edge of ventral surface;
length 0.62 basis length; length 1.5 width.
Ambulatory Pereopods (fig. 2.28A-B):
0.31 body length.
Bases I-IV subequal, lengths
In male, pereopod I length 1.2 body length; ischium
length 0.63 basis length.
Natatory Pereopods (fig. 2.28C-E):
Pereopod VII absent in adults.
Natapods heterogeneous in form: pereopod V large, with elongate
ischium and merus, broad carpus and propodus and tiny dactylus;
pereopod VI much smaller, with narrowed carpus and propodus and long
thin dactylus.
respectively.
Pereopods V-VI length-body length ratios 0.86 and 0.69
Coxa V large, robust, broader than length of basis;
coxa VI small, much narrower than length of basis.
Bases V-VI shorter
than bases I-IV; length-body length ratios 0.11 and 0.17,
respectively.
Pereopod V merus length 0.73 ischium length.
VI length-width ratios 1.1 and 1.7, respectively.
length-width ratios 1.9 and 2.9, respectively.
Carpi V-
Propodi V-VI
Dactyli V-VI length-
propodus length ratios 0.14 and 0.63, respectively.
147
Figure 2.28.
Mimocopelates longipes new genus, new species.
E, holotype male, bl 2.1 mm.
ｾＮ＠
A,
c-
A, bases ot right pereopods I-IV, in
B, lett pereopod I, paratype male, bl 2.1 mm, with enlargement
ot dactylar claw.
dactylus.
C, right pereopod V,
D, right pereopod VI,
ot dactylar tip.
ｩｮｾＮ＠
Ａ｡ｾＬ＠
with enlargement ot
E, pereopod VI enlargement
Illustrations all to same scale.
148
.. ｾ＠
...
ｾ＠
I
-
c
149
Male Pleopod I (fig. 2.29A-0).
Fused pleopod pair highly convoluted:
widest at rounded enlarged portion just distal to insertion, narrow
waist at midlength in ventral view, dorsal locking folds enlarged,
extending dorsally more than half depth of fused pleopod pair, dorsal
stylet guides with dorsal edges extending medially and almost forming
tubes, proximal funnel for elongate curved penes opening 0.22 length
of fused pleopod pair.
pleopod width.
Length 3.1 width; width at dorsal orifice 0.56
Dorsal orifice 0.25 total length from distal tip.
Distal tip flattened, distally rounded in lateral view, curved in
ventral view; outer lobes appearing as small lateral corners.
Each
side of distal tip with 4 distinct groups of setae: 3 simple setae on
lateral margins; 4 setae just medial and dorsal to outer tips; 4 setae
on ventral side of distomedial margin; 4 unusual fat based setae on
ventral surface, inner seta distinctly smaller than others.
Fused
pleopod pair of juvenile male ventrally flattened, not convoluted,
lacking distal setae.
Male Pleopod II (fig. 2.29D-E):
Protopod robust, muscular, laterally
rounded, lacking lateral fields; length 1.8 width; approximately 9
plumose setae projecting dorsally on distolateral margin.
Stylet
short, distal tip not extending beyond protopod, length 0.47 protopod
length; proximal sperm duct opening 0.34 stylet length from distal
tip; stylet inserting 0.33 protopod length from distal tip.
Exopod
short, not extending medially beyond inner margin of protopod, with
tuft df fine setae on dorsal side.
150
Figure 2.29.
Mimocopelates longipes new genus, new species.
pleopods I-II, paratype male, bl 2.1 mm.
paratype preparatory female, 1.9 mm.
A-E,
F-L, pleopods II-V,
A-O, pleopod I, ventral view
with enlargement of distal tip, lateral view, and dorsal view of
distal tip, respectively.
D-E, left pleopod II, ventral view and
dorsal view of distal tip with enlargement of stylet tip,
respectively.
F-H, right pleopods III-V.
I-L, pleopod II:
ventral, lateral, posterior, and dorsal views, respectively.
151
152
Female Pleopod II (fig. 2.29I-L): Operoular pleopod pair triangular in
ventral view, with tiny fused groove in distal tip.
Keel broad,
rounded, lateral fields not distinot from sides of keel; row of fine
setae along keel.
Lateral margins ourling dorsally, distal part with
simple setae grading into plumose setae.
length.
Apex ventral to insertion,
｢ｾｴ＠
Length 1.3 width; depth 0.37
not extending anteriorly; apex
laoking large seta.
Pleopod III (fig. 2.29F): Exopod narrow distally, extending to tip of
endopod, with 2 long plumose setae, and 1 simple seta on distal tip.
Endopod with 3 distal plumose setae.
Uropod'(fig. 2.27G-H): Protopod broader than long, medial length 0.74
distal width; medial length 0.03 body length.
simple setae.
Exopod tiny, with 2
Endopod 1.3 medial length of protopod.
Distal margin
of protopod with 2 simple setae on posteromedial oorner.
Remarks.--Mimooopelates longipes may be distinguished from the 3 other
similar speoies (ourrently undesoribed) of this genus by the following
oharaoters.
The oephalio vertex is unmarked by a outioular line so
that the oephalio dorsal surfaoe curves direotly into the frons.
The
antennulae are set fairly far apart oompared to one speoies where the
interantennular distanoe is small.
The uropodal endopods are longer
Many
and narrower than those seen in other similar speoies.
oharaoters distinguish
anohibraziliensis.
ｾ＠
longipes from the muoh larger
ｾ＠
A less massive head that is reoessed into the
first pereonite, and a large biramous uropod are probably the easiest
oharaoters b.Y whioh to identify
ｾ＠
longipes.
153
The setal groups on the tip of male pleopod I (fig. 2.29A) are
unique, and are exactly the same for all males of
northeastern Atlantic.
ｾＮ＠
longipes from the
The males of this species from the Western
Atlantic may have a large medial fat-based seta instead of a small
one.
Only fully mature males may be used for these male pleopod
"":;.a,
characters because the preoeding juvenile male instar has a flat,
almost featureless pleopod I.
Maturity may be judged in this species
(as in most Janiroidea) by a pleopod II stylet sperm tube whioh is
open at both ends.
Juvenile males generally have either olosed or
absent sperm tubes.
ｾＮ＠
longipes has a broad distribution, both vertioally and
geographioally, oompared to distributions of other euryoopids from the
north Atlantio (Wilson, 1983a, 1983b).
of the same looalities as the
!.
This speoies is found in some
oomplanata oomplex (Wilson, 1983b),
leading one to wonder whether a oryptio speoies oomplex is present.
It is replaoed, however, at a oentral North Atlantio station (WHOI
334) by another undesoribed speoies, suggesting that it is limited to
proximity of the oontinental margins.
154
Mimocopelates anchibraziliensis new species
(Figures 2.30 - 2.32)
Holotype.-Preparatory female, bl 4.2 mm, USNM; distal parts of
antennae, and pereopods I-IV broken off.
Paratypes.-Copulatory male, bl 3.2 mm, USNM; 20 additional specimens,
';.iP
some dissected for description, SIO.
Type-Locality.--WHOI 169: 080 02.0-03.0' S, 340 23.0-25.0' W, 587 m,
collected on 21 February 1967 during R/V Atlantis II cruise no. 31.
Other Material.-- WHOI 167, 72 mostly fragmentary individuals; WHOI
159, 7 individuals; WHOI 162, 1 individual.
General Distribution.--Equatorial Atlantic Ocean off Brazil,
587-1493 m.
Derivation of Name.--This species of Mimocopelates was given the name
anchibraziliensis because it is found near Brazil in the bathyal
waters offshore.
Diagnosis.-Cephalon massive, heavily calcified, wider than pereonite
1, anteriorly flattened.
Cephalic vertex linear medially, distinctly
separating frons trom cephalic dorsal surface.
Cephalic frontal arch
recessed into frons, not protruding beyond vertex in dorsal view,
nearly vertical in lateral view.
mandibular articulation.
Cephalon lacking indentation at
Widths of antennular articles 1 sexually
dimorphic, wider in adult males than in adult females: in females,
155
Figure 2.30.
Mimocopelates anchibraziliensis new species.
A-B,
holotype preparatory female, lateral and dorsal views, scale bar 1.0
mm.
C, paratype male, dorsal view.
D-E, cephalon, lateral and
anterior views, paratype preparatory female, bl 4.4 mm.
F, cephalon
and mandible, ventral oblique view, paratype male, bl 3.5 mm.
mandibles, preparatory female, bl 4.4 mm.
view.
G, right mandible, dorsal
H, left mandible, ventral view, palp omitted.
incisor process and lacinia mobilis, plan view.
incisor and molar processes, dorsal view.
G-J,
I, left
J, left mandible,
156
157
distance between medial corners of antennular insertions 0.19 (2 inds)
cephalon width; in males, 0.10-0.11 (2 inds).
distally scalloped.
Maxillipedal epipod
Male pleopod I distal tip with following paired
setal groups: 5 fat-based setae ventral to dorsal orifice, 7 setae
distally, and 4 setae laterally.
Uropodal endopod length 1.9 width,
length shorter than protopod width, ratio
0.9; protopod distomedial
-;:..
corner rounded, not projecting; exopod absent.
Description.--Body Characters (fig. 2.30A-C): Adult females larger
than males, female body length 4.2-4.4 mm (2 inds), male body length
3.2-3.5 mm (2 inds).
Length 2.7 width in both sexes.
Pleotelson
lengths sexually dimorphic: male pleotelson length 0.38 body length (2
inds); in female, 0.34-0.35 (2 inds).
Body setation (fig. 2.30A-C): All dorsal surfaces with few scattered
fine setae.
Cephalon. (fig. 2.30D-F): All surfaces heavily calcified, especially at
anterior margins, with large plate-like crystals in cuticle.
female, dorsal length 0.50 width, length 0.76 height.
In
Ventral margin
at posterior articulation of mandible heavily calcified, with no
indentation or notch.
158
Figure 2.31.
Mimocopelates anchibraziliensis new species.
A-B,
right antennula, lateral and dorsal views, paratype male, bl 3.5 mm.
C-H, paratype preparatory female, bl 4.4 mm.
C-D, dorsal views of
left antennula: articles 1 and 2, and proximal 5 articles
respectively.
E, left maxillula.
of distal tip of basis.
dactylus.
F, left maxilliped with enlargement
G, right pereopod V, with enlargement of
H, right pereopod VI.
159
160
Antennula (fig. 2.30A-B, 2.31A-D): Strongly dimorphic sexually: male
antennula longer, with higher number of more robust articles, than in
female.
Female antennula length 0.39 body length (not intact in any
males seen); female antennula with 18-19 articles (holotype only).
Article 1 larger in males: width 0.36-0.37 (2 inds) cephalon width in
males, 0.24-0.26 (2 inds) in females; article 1 medial lobe distinct
ｾ＠
but shorter than lateral lobe, length 0.49 width in male, 0.59 in
female; medial lobe of both sexes with approximately 4 broom
ｳ･ｴ｡ｾ＠
Article 2 with blunt lateral spine bearing 2 broom setae; article 2
length 0.67 article 1 medial lobe length in female, length 1.1 medial
lobe length in male.
Article 3 length 0.75 article 2 length in
female, 0.89 in male.
Flagellar articles longer than wide in females,
wider than long in males.
Mandible (fig. 2.30F-J): Mandibles of both sexes heavily sclerotized
and calcified.
processes.
Both mandibles with 3 distinct cusps on incisor
Lacinia mobilis narrower than incisor process, with 6 low
cusps. Left spine row with 4 members, right spine row with 5.
Molar
process distally dome shaped, with no circumgnathal denticles or
cusps; posterior margin with 3 serrate setae; no sensory pores visible
on triturating surface.
Condyle strong, with anterior and posterior
shelves; length 0.36 mandibular body length.
Palp second article
length 0.47 mandibular body length; distal article thin, forming
moderate flat curl.
Maxilliped (fig. 2.31F): Ventral surfaces of basis, palp article 2,
and epipodite with cuticular ridges and few setae.
Basis with 4-5
161
receptaculi and 6 fan setae distally; 4 lateral fan setae bifid with
distinct gap separating both sides; medial fan seta small, truncate;
seta second from middle behind third seta more robust, with fewer and
broader branches than 4 lateral fan setae.
length 0.51 total basis length.
Endite distally quadrate,
Palp article 2 width 2.0 endite
width, lateral length 2.0 medial length.
Palp article 3 lateral
Ｍｾ＠
length 0.22 medial length.
Epipod short, round, broadly concave
distally; length 0.66 basis length; length 1.5 width.
Pereopodal Bases: Bases I-IV short, not subequal to each other:
length-body length ratios 0.19, 0.17, 0.18, 0.19, respectively.
Natatory Pereopods V-VI (fig. 2.31G-H): Basically similar to those of
Mimocopelates longipes.
0.54,
ｲ･ｳｰ｣ｴｾｶｬｹＮ＠
Pereopod V-VI length-body length ratios 0.65,
Pereopod V merus length 0.82 ischium length.
Carpi V-VI length-width ratios 1.1, 1.3, respectively.
Propodi V-VI
length-width ratios 1.8, 2.6, respectively.
Male Pleopod I (fig. 2.32A-D).
Fused pleopod pair not highly
convoluted: widest proximally, tapering gradually to narrow distal
end, curving smoothly in lateral view, with small dorsal locking
folds.
Length 5.6 width; width at dorsal orifice 0.48 pleopod width.
Dorsal orifice close to distal tip: 0.09 total pleopod length from
distal tip. Distal tips similar in shape to Mimocopelates longipes.
Penes elongate, curving posteriorly and down from ventral surface
before entering proximal sperm tube funnel of fused pleopod pair.
162
Figure 2.32.
Mimocopelates anchibraziliensis new species.
paratype male, bl 3.5 mm.
view.
A-J,
A, pleotelson and pereonite 6, ventral
B-D, pleopod I: B, lateral view with enlargement ot ventral
tat setae; C, ventral view with enlargement ot distal tip; D, dorsal
view ot distal halt.
E-G, pleopod II: E, lett side, ventral view;
F, right side, lateral view; G, lett side, enlarged dorsal view ot
distal tip.
H-J, right pleopods III-V.
paratype preparatory temale, bl 4.4 mm.
bl 4.2
mm,
ｾＬ＠
K-L, pleopod II,
M, uropod, holotype temale,
proximal portion seen through outiole.
163
ｾ＠
F
ｾＭ
... L
ｾ＠
I
164
Male Pleopod II (fig. 2.32E-G):
Protopod elongate, triangular, deeper
in distal half where exopodal musculature attaches; length 2.3 width.
Dorsally recurved distolateral margin with approximately 6 plumose
setae.
Stylet small with short sperm tube, length 0.30 protopod
length; sperm duct proximal opening one third total stylet length from
distal tip; endopod inserting 0.19 length of protopod from distal tip.
:'-lo<
Exopod small, with fine setae on dorsomedial side.
Female Pleopod II (fig. 2.32K-L): Keel broad, with shallow rounded
anterior prow and low hump 0.37 total length from proximal end; keel
curving smoothly into rounded lateral fields.
few setae.
Ventral surface with
Distolateral margins strongly recurved dorsally with
approximately 11 plumose setae on each side.
Length 1.3 width; depth
0.41 length.
Pleopod III (fig. 2.32H): Exopod distally rounded, longer and wider
than endopod, with 2 distal plumose setae and no apparent joint.
Endopod with 3 distal plumose setae; setae longer than endopod.
Pleopods IV-V (fig. 2.32I-J): Endopods of both limbs thick and
triangular in ventral view.
Exopod of pleopod IV long, flattened,
lobe-like, with single long plumose seta.
Uropod (fig. 2.32M): Uropods small, uniramous, recessed into
ventromedial margin of posterior pleotelson; only distal tip of
endopod visible in lateral view.
width.
Protopod medial length 0.56 distal
Endopod 1.6 medial length of protopod.
Distal margin of
protopod with few long setae, posterior margin lacking projection.
165
Remarks.--Mimocopelates anchibraziliensis n.sp. is a very distinctive
species: members are large, exceeding 4 mm as adults, the uniramous
uropods are very tiny, and the cephalon is enlarged and heavily
calcitied.
In addition to these characters, the flat, triangular male
pleopods are distinctly different from the robust, highly convoluted
pleopods of
!:. longipes.
In fact, the male pleopods II of
!:.
anchibraziliensis are somewhat reminiscent of those seen in some
Munnopsidae whose endopods, exopods, and intrinsic musculature are
reduced.
This species was collected only in a bathyal transect of
stations off Recite, Brazil.
CHAPTER 3
AMULETTA, A NEW GENUS FOR ILYARACHNA ABYSSORUM RICHARDSON 1911
(ISOPODA, ASELLOTA, EURYCOPIDAE) 1
by George D.F. Wilson and David Thistle2
"'"
ABSTRACT
Amuletta, new genus, is proposed for Ilyaracbna aBlssorum
Richardson 1911.
A detailed description, new illustrations, and new
records are presented with a discussion of the systematic position of
this species.
It must be placed in the Eurycopidae, in spite of its
resemblance to the presumed ancestor of the Ilyarachnidae.
This
difficulty arises because the present classification of these
janiroidean families has become obsolete.
This species is apparently
limited to the northeast Atlantic, where it has a broad depth
distribution.
However, sampling device avoidance may account for the
infrequent records of this species, implying it may have a broader
geographic range.
The gut contents of one specimen contained a high
proportion of calcareous Foraminifera, suggesting that it was actively
feeding on forams.
1 This chapter was published as an article of the same title and
authorship in the Journal of Crustacean Biology, volume 5, pages
350-360, 1985.
2 Second author: David Thistle, Associate Professor of Oceanography,
Florida State University, Tallahassee, Florida.
166
167
INTRODUCTION
Ilyarachna abyssorum Richardson 1911 has been an enigma since it
was described.
Richardson's original description was brief, and she
provided no figures.
Fq.rther, she was unsure of the appropriateness
of placing the new species in Ilyarachna.
Ilyarachna abyssorum was
pivotal in discussions of the origin af the Ilyarachnidae by Thistle
and Hessler (1976), who treated it as Ilyarachna.
Schultz (1976), on
the other hand, transferred the species to Echinozone.
with the placement of
ｾ＠
Difficulties
abyssorum arise, at least in part, from the
intermediate nature of this species.
Witness, for example, Thistle
and Hessler'S (1976) arguments that the species can be used to
understand the evolutionary transition from the Eurycopidae to the
Ilyarachnidae.
In this paper, we hope to dispell confusion about
ｾ＠
apyssorum by presenting a discussion of its systematic position and a
diagnosis of a new genus; Amuletta, based on a complete redescription
of the original type-specimens and new material from the Northeast
Atlantic.
168
MATERIALS AND METHODS
The types of Ilyarachna abyssorum were kindll lent to us by Dr.
J. Forest, Museum National d'Histoire Naturelle, Paris, and Dr. T.E.
Bowman, National Museum of Natural History, Washington, D.C.
Additional specimens came from the research collection of Dr. R.R.
Hessler, Scripps Institution of Oceanograph1, the sources of which are
described in Wilson and Hessler (1980).
The descriptive terms and methods used here are those of Thistle
and Hessler (1977) and Wilson and Hessler (1980).
In the following
discussions, the term "munnopsoids" is taken to refer to an informal
(but useful) taxon made up of the truly natatory families of the
Janiroidea: Munnopsidae, Eurycopidae, and Ilyarachnidae.
169
THE SYSTEMATIC POSITION OF ILYARACHNA ABYSSORUM
Richardson (1911) placed the species abyssorum into Ilyarachna
because of apparent similarities to known species of that genus.
felt abyssorum most resembled
ｾ＠
plunketti Tattersall 1905a (=
She
ｾ＠
longicornis Sars; see Thistle, 1980) but noted that the two species
differed in the form and the position"'ofepimeres of the anterior four
pereonites, the size and the shape of natasomal segments, and the
shape of the carpus of pereopod VII.
These observations have gone
unnoticed in the literature until their significance became apparent
during our redescription of abyssorum.
Our work on the families Eurycopidae and Ilyarachnidae has
convinced us that Richardson's familial placement of abyssorum must be
revised.
Below we present arguments for the removal of the species
from the Ilyarachnidae, and its placement in a new genus of the
Eurycopidae.
Richardson (1911) mentioned that the carpus of pereopod VII was
broadened in abfssorum.
Among munnopsoids, this is a primitive
character state with respect to all Ilyarachnidae, in which the last
pereopod is reduced to an almost ambulatory-appearing condition.
Al though none of our adult specimens retained this limb segment,
Richardson's statement is corroborated by two bits of evidence.
First, inspection of a sagittally bisected individual showed that
pereoni te 7 is as well muscled as the anterior natasomal segments and
is not reduced as in Ilyarachna.
Also, the basis of pereopod VII is
nearly as robust as that of pereopod VI (fig. 3.1G), rather than
170
clearly thinner as in Ilyarachna.
Second, in the manca 3 of
agyssorum, the carpus of the developing pereopod VII (fig. 3.1E) is
somewhat broadened, a condition intermediate between that seen in the
Eurycopidae (e.g. Eurycope iphthima, see Wilson, 1981) and that of the
Ilyarachnidae, such as I. antarctica.
Taxa in which the adult limb is
not broadened show no broadening in tne manca 3 pereopod VII.
Therefore, the seventh pereopod carpus of abyssorum is likely to be
wider than that of the ilyarachnids, but narrower than in the
eurycopids.
In abyssorum, the mandibular molar process (fig. 3.2H,L) is
little modified from the primitive janiroidean condition; it is
distally broad, concave, with many setae and teeth on its distal
margins.
This morphology is different from the reduced, setiferous
molar process used as a primary diagnostic character of the
Ilyarachnidae by Wolff (1962). The rest of the abyssorum mandible
(fig. 3.2F-N) is different from that typical of ily-arachnids.
The
incisor process is not reduced and rounded, the mandibular body is not
shortened, and the dorsal condyle is small, rather than elongate and
curved.
Because the mandible is not highly specialized as in the
ilyarachnid condition, the cephalon is not greatly broadened to
accomodate enlarged mandibular articular supports.
All these
mandibular characters in abyssorum are primitive compared to those of
the Ilyarachnidae.
171
The mandibular palp is absent in abyssorum but the generalized
form of the mandible indicates that this reduction was derived
independently of the Ilyarachnidae.
The absence of a palp in some
genera of the Ilyarachnidae, such as Echinozone, is convergent because
the highly modified ilyarachnid mandible has a palp in other genera.
The significance of the agyssorUm uropod requires the comparison
of the primitive state of this character within the munnopsoids,
determined through inspection of the uropods of other janiroidean
families, such as the Desmosomatidae and the Janiridae.
The primitive
uropod has a tubular protopod that may be oval in cross-section, and
two elongate, unequal rami; the distal margins of the protopod and the
rami have rows or groups of setae.
EBfYcope and Storthyngura.
This is the type of uropod seen in
The uropod of abyssorum (fig. 3.1I-K) is
modified from the primitive condition: the distal margin of the
protopod is elongated medially and tilted to face laterally, and the
rami are very short and stout.
The protopod, however, is not
flattened but is more or less oval in cross-section.
All members of
the Ilyarachnidae have a flattened, foliaceous uropodal protopod, and
the rami are reduced or absent, a morphology even further removed from
the primitive munnopsoid uropod than that of apyssorum.
If the
abyssorum uropod form is related to that of the Ilyarachnidae, it is
as a preoursor.
The triangular natasome and the enlarged cephalon
with no rostral projection in abyssorum (figs. 3.1A, 3.2A-E) is
characteristic of the Ilyarachnidae.
This general facies, however, is
1:72
"
Figure 3.1.
10.3 mm.
.........
A-B, paralectotype female (USNM 42172), body length (BL)
A, dorsal view, scale bar at left is 2 mm long.
B, ventral
oblique view.
e,F, lectotype preparatory female. e, dorsal view. F,
lateral view.
D-E, I, manca 3, WHOI 328.
at lower right is 1 mm long.
D, dorsal view, scale bar
E, ventral view of pleotelson.
G-H,
female paralectotype natasome fragment, "Talisman" station 135.
lateral view.
H, dorsal view of pleotelson.
I-J, female
paralectotype pleotelson fragment, "Talisman" station 134.
ventral view of pleotelson, pleopod II in plan view.
ｾＬ＠
lateral view.
I, uropod, ventral view.
G,
J,
I, oblique
uropod, in
173
174
Figure 3.2.
A, C, E-F, H-N, preparatory female, estimated BL 14.9 mm,
INCAL WS02.
B, lectotype female.
station 135.
G, paralectotype male, "Talisman"
A-E, cephalon, scale bar to right of A is 1 mm long: A,
frontal oblique view, right antennula and antenna removed;
ventral view, all mouthparts in place;
removed;
D, dorsal oblique view;
antenna removed.
ventral view;
posterior view;
ventral view, maxilliped
E, lateral view, antennula and
F-N, left mandible, scale bar to right of F is 0.5
mm long: F,I, dorsal view;
of distal parts;
C,
B,
G, dorsal view;
J, lateral view;
H, dorsal oblique view
K, lacinia mobilis and spine row,
L, molar process, posterior view;
M, incisor process,
N, lacinia mobilis, posterior view.
175
176
also found in the Syneury-copinae, Storthyngura, and in Betamorpha.
If
these characters are useful for determining phylogenetic affinities,
thel define a group larger than the famill Ilyarachnidae.
Hessler and Thistle (1975) believed the primary character
identifYing the members of the Ilyarachnidae to be the shortened bases
of the third and fourth pereopods.
Although the bases of pereopods
III and IV are shortened in abyssorum (fig. 3.1B,F), they are not as
short as in the Ilyarachnidae.
The use of this character as a unique
descriptor of the Ilyarachnidae is in doubt because
ｳｨｯｲｴ･ｮｾ＠
bases
III-IV are found in Bellibos hugsness and Hessler 1979, Munneurycope
nodifrons (Hansen, 1916) and similar species, and to a lesser extent
in some species of Storthyngura.
Extremely short, robust bases of
pereopods III and IV are also characteristic of the Munnopsidae.
Although the short bases of the Munnopsidae mal have been derived
independently, the other taxa mentioned above mal delineate a
transformation series from the elongate bases III-IV considered to be
primitive in the munnopsoids, to the short and robust ones typical of
the Illarachnidae.
be intermediate.
The form of the bases in aprssorum would therefore
Although this view may disagree with Thistle and
Hessler'S (1976) contention that the length of the bases III-IV
provides the diagnostic difference between the Ilyarachnidae and the
Eur,ycopidae, we believe that the ilyarachnids are still diagnosable bl
the unique shape of their cephalon and mandibles, their uropods, their
reduction of the seventh pereopods, and their general body form.
177
In sum, no character shared between the Ilyarachnidae and
abyssorum is unique to these taxa.
Therefore, we conclude that
abyssorum must be placed in the Eurycopidae, in spite of the
possibility that this species may be similar to the ancestral
ilyarachnid.
This ancestor would not be included in the same genus
with abyssorum because it would have had a mandibular palp.
Much of the difficulty with determining the position of abyssorum
lies not in indecision about the meaning of its characters, but in the
general weakness of the present system of classification of the
munnopsoid families.
The Eurycopidae, as the central taxon of the
munnopsoids, should be recognized as paraphyletic, containing members
of related phyletic lines leading to the various subfamilies of the
Eurycopidae, and to the Ilyarchnidae and the Munnopsidae.
The
confusion in the present classification occurs because the advanced
members of the eurycopid subfamilies are no more similar to each other
than they are to the other families of the munnopsoids.
Despite these
dissimilarities, intermediate taxa such as abyssorum and Betamorpha
eliminate distinct gaps which would simplify the classification,
increasing the difficulty but not the interest of munnopsoid
systematics.
Research in progress by one of us (GDFW) on eurycopids
having the ilyarachnoid facies (Wilson and Hessler, 1981) and other
taxa in the Eurycopidae will attempt to reclassify the munnopsoid taxa
in a more phylogenetically natural fashion.
We will not, therefore,
suggest a subfamilial placement for the new genus Amuletta, proposed
here for the species abyssorum.
178
Amuletta new genus
Type-Species.-- Ilyarachna a£yssorum Richardson 1911, b,y monotypy.
Diagnosis.-- Dorsal surface of body without spines.
Cephalic lateral
margins not greatly broadened; frontal area without rostrum, but with
2 medial protrusions: small dorsal
ｬｯｾ･＠
between closely adjacent
antennulae; supraclypeal ridge enlarged, thick and rounded medially,
flattened laterally under antennal insertions.
Segments of natasome
flexibly articulated and distinct ventrally, decreasing in width
posteriorly.
Pleotelson distinctly longer than wide, with rounded
posterior tip in dorsal view.
Antennular first article longer than
wide, thick and rounded distomedially, flattened and projecting
anteriorly on distolateral margin.
without palp;
Antenna without scale.
incisor process and lacinia mobilis cuspate;
Mandible
molar
process large, with many setae and teeth on circumgnathal margin.
Coxal plates on pereopods I-III with pointed anterior projections;
pereonite 4 anterolateral corner protruding in similar manner.
Bases
of pereopods III-IV two-thirds length of basis II, with distinct
lateral bumps.
Bases of natatory pereopods as long as or longer than
bases of ambulatory pereopods.
carpus, not reduced.
Pereopod VII with broad natatory
Uropodal protopod not foliaceous,
subcylindrical, pointed distomedially, with 2 distinct rami.
179
Derivation ot Name.--Amuletta (teminine) is derived from the French
word tor amulet or talisman, reterring to the "Talisman", the ship
trom which the genus was tirst collected.
Generic Remarks.--Within the Eurycopidae, Amuletta is most similar to
Betamorpha, Bellibos, and some species ot Storthyngura.
These
similarities are in the general shape of the body, cepha.lon,
antennulae, antennae, pereopods, and pleopods.
however, is unique in some way.
Each ot these genera,
Amuletta's small distomedial lobe on
the uropodal protopod and lack ot a mandibular pa.lp make it
immediately distinct from Betamorpha.
The natatory pereonitesot
Bellibos are fused into one inflexible unit, unlike the free
pereonites ot Amuletta.
Species ot Storthyngura that lack lateral
and dorsal spines do not have the compact uropod with short rami or
the triangular pleotelson ot Amuletta.
As discussed above, this genus
cannot be confused with the genera ot the Ilyarachnidae because it
does not have the specialized cepha.lon, mandibles, seventh pereopods,
and uropods ot that tamily.
180
Amuletta abyssorum (Richardson)
Synonymy.--llyaraehna abyssorum, Richardson 1911, p. 533;
abyssorum, Hessler and Thistle 1975, p. 157;
1976, pp. 112-113;
Ilyarachna
Thistle and Hessler
Eehinozone abyssorum, Schultz 1976, p. 10.
Lectotype.--Fragmentary preparatory
ｴｾｭ｡ｬ･＠
(designated trom syntype
series) from Northeast ot the Azores, "Talisman" dredge station no.
134, 4060 m., 420 19' N, 23 0 36' W, 24 August 1883 (station no. 147
in Smith, 1889; see appendix in Crosnier and Forest, 1977), deposited
in Museum national d'Histoire naturelle, Paris.
Features of type:
only head and anterior 5 pereonites remaining; right pereopods
represented by at most coxa and basis.
Paralectotypes.-Four fragmentary specimens, "Talisman" dredge station
no. 134;
3 fragmentary specimens, "Talisman" dredge station no. 135
(149 in Smith, 1889), 4165 m., 43 0 15' N, 21 0 40' W, from Northeast of
the Azores, 25 August 1885; deposited in
de Paris.
ｍｵｳｾｭ＠
d'Histoire naturelle
Preparatory female, body length 10.3 mm, "Talisman" dredge
no. 135, deposited in the United States National Museum of Natural
History (possibly by Richardson), catalog number USNM 42172.
Additional Material.-Four juvenile specimens (one is a cephalon
fragment only), Woods Hole Oceanographic Institution deep benthic
station (WHOI) 328, 4426-4435 m., 500 4.7' N, 150 44.8' W, 23 August
1972, Southeast of Ireland.
One manca, "Sarsia" station 50 (collected
by John Allen, University Marine Biological Laboratories, Millport,
Isle of Cumbrae, Scotland), 2379 m., 43 0 46.7' N, 30 38' W, 18 July
181
1967, in the Bay of Biscay.
Preparatory female, pleotelson missing,
estimated body length 14.9 mm, completely dissected for illustration,
Expedition "Intercalibration" (mCAL; for description ot program, see
Sibuet, 1979) station WS02, 2498-2505 m., 500 19.3'-20' N, 120 55.8'56.0' W, 30 July 1976.
Copulatory male, body length 13 mm, partially
dissected for illustration, mCAL ｳｴ｡ｾｩｯｮ＠
WS04, 4829 m., 480 18.9'-
18.3' N, 150 14.4'-13.3' W, 2 August 1976.
General Distribution.--Ab,yssal Northeast Atlantic, 2379-4829 m.
Description.--Body Characters (fig. 3.1A-H): Total body length 2.8
times body width, in manca length 2.9 times width; body widest at
pereonite 4.
Adult body lengths range trom 10.2 mm (preparatory
female, USNM 42172) and 13 mm (copulatory male, mCAL WS04) to 14.9 mm
(preparatory female, mCAL WS02, estimated length);
328) body length 4.1 mm.
manca 3 (WHOI
Dorsal surface of pereonites with scattered
simple setae; pereonites 1-5 with row of setae on anterior margins;
marginal setae decrease in size posteriorly.
Dorsal surface of
pereonites complex: anterior margins flaring slightly upward,
posterior margins distinctly depressed under flange of next posterior
pereonite, patches of cuticle over muscle attachments slightly raised
or depressed.
Pleotelson length 1.1 - 1.4 times width in adult,
length 1.4 times width in manca 3.
Cephalon (fig. 3.2A-E): Cephalon length in dorsal view from
dorsal antenna! socket margin to posterior articulation 0.39 times
width (2 females measured); in manca 3 length 0.43 times width.
Dorsal surface domed, slightly bilobed by medial sagittal depression;
182
surface with many setae, sometimes on low cuticular bumps on dorsum,
very fine setae on sides.
rows of setae.
row of setae.
Anterior margins of antennal sockets with
Posterior margin with rounded transverse ridge having
Clypeus short, broad, dorsally rounded, shorter than
length of labrum.
Antennula (fig. 3.3A-B): Basal article longer than broad, length
1.4 times width;
medial and central part thick; lateral margin thin,
flattened, anteriorly projecting, with unequally bifid and simple
marginal setae.
More distal articles elongate and thin.
Second
article slightly longer than third article, length 0.54 times basal
article length (about 0.6 in male).
length of article 3.
Article 4 less than one-fifth
Broom setae on proximal 2 articles only.
In
male, flagellar articles shorter, wider and more numerous than in
female; each article of about distal two-thirds of flagellum with
single aesthetasc inserting ventrally.
Antenna (fig. 3.1B, 3.2A-D): Basal 4 segments large, robust,
indicating long appendage.
Basal segments decrease in width distally.
Scale on third article absent, former position possibly marked by
clump of setae.
Left Mandible (fig. 3.2F-N): Incisor process with 3 teeth.
Lacinia mobilis with 4 teeth, broad grinding surface posterior to
teeth, and many hair-like spines on ventral surface.
Spine row with
11 members on strongly curved and compressed basal ridge.
Molar
process large, with 13-17 setae on distal posterior edge; distal
183
triturating surface concave, oval, heavily cuticularized, with
distinct sensory pores.
Dorsal condyle shorter than molar process,
somewhat recessed into mandibular body.
Posterior part of mandibular
body with large articular lobe.
Maxillula (f1g. 3.3F): Inner lobe very setose, nearly as long as
outer lobe, with one large distal seta.
Outer lobe with 12 claw-like
setae, one spine-like seta at base of sixth claw seta from lateral
end, and row of thin flattened setae at ventral base of larger distal
setae; second large seta from outside resting in concavity on medial
surface of first seta.
Maxilla (f1g. 3.3G): Inner lobe wider than both outer lobes
together.
All lobes very setose.
Basal region covered with many
cuticular combs.
Maxilliped (fig. 3.3H-I): Endite with 7-9 coupling hooks in
adult (3 in manca 3);
distal tip sharp-toothed laterally with 9 short
(4 in manoa 3) and 1 long fan setae; endite length (measured from
medial insertion of palp to distal tip) 0.32 times total basis length.
Palp article 2 width 1.2 times endite width; medial length 0.38 times
lateral length.
length.
Palp article 3 medial length 3.0 times lateral
Epipod distally rounded with no lateral projection; length
2.2 times width.
Pereopod I (fig. 3.3C-D): L1mbrobust.
Basis longest segment.
Ischium with row of setae on dorsal distomed1al margin.
Merus w1th
184
8
Figure 3.3.
A, 0, E-I, preparatory female, INOAL WS02.
are all 0.5 mm long;
male, INOAL WS04.
A, 0, E, H have the same scale.
B, copulatory
D, paralectotype female, USNM 42172.
antennula, distal articles missing.
0, pereopod I.
Scale bars
A-B,
D, pereopod I
dactylus, medial view.
E, paragnaths.
of distolateral setae.
G, maxilla, with enlargement of setal combs on
mediobasal region.
endite distal tip.
H, maxilliped.
F, maxillula, with enlargement
I, enlargement of maxilliped
185
patch of setae on ventral distomedial margins.
Carpus length 0.88-
0.92 times basis length, with 23-36 setae on opposing margin of
carpus.
Propodus length 0.69-0.72 times carpus length.
Bases of Pereopods I-VII (fig. 3.1B, F-G): Basis VI longest,
bases III-IV shortest; basis
length ratios 0.13, 0.17,
ｬ･ｮｧｴｨｾ｢ｯ､ｹ＠
0.11, 0.11, 0.15, 0.20, 0.17, respectively.
Bases III-IV with
distinct lateral bump about midway along length.
Basis VII as robust
as bases V-VI.
Male Pleopod I (fig. 3.41-C): Pair complex long and narrow,
widest proximally, narrowest distally, length 3.4-3.5 times proximal
width, length 8.5 times width at dorsal orifice.
Dorsal orifice close
to distal tip, 0.09 times total pleopod length from distal tip.
Ventral surface with broad paired rows of many plumose setae extending
nearly full length of pleopod.
Distal tip with 3 paired, dense groups
of simple setae: on dorsal surface of distal margin, on ventral
surface behind outer lobe, on ventral surface in broad row extending
proximally from region below dorsal orifice to around two-thirds
length of pleopod.
Inner lobe rounded; outer lobe bluntly recurved.
Male Pleopod II (fig. 3.4D-F).
Protopod length 2.3 times width;
many plumose setae on lateral margin and posterior half of ventral
surface; simple setae on ventral surface below exopod.
Endopod and
exopod small, inserting close to distal tip; endopod inserting 0.26
times total protopod length from distal tip.
•
beyond distal tip;
Stylet not extending
length 0.39 times total protopod length;
tip of stylet with tiny lateral denticles.
distal
Exopod with very dense
186
group of fine simple setae on posterior curve.
Female Pleopod II (fig. 3.1 E, I): Operculum narrow with deep
Length 1.9 times width in manca 3.
keel.
Keel narrow, ventrally
rounded, with no distinct apex nor setae. Lateral margins and
posterior part of lateral fields with.many plumose setae.
Distal tip
bifurcate with distinct incision, incision length subequal to medial
length of uropodal protopod.
Pleopod III (fig. 3.4G): Endopod with around 14 distal brush
setae in adult.
hopod narrow, length 5.6 times width, rounded with
around distal 8 brush setae in adult, lateral margin with small
plumose setae on proximal article.
Pleopod IV (fig. 3.4H): hopod narrow, decreasing in width
distally, with 3 brush setae on tip.
Uropod (fig. 3.1E, I-K): Protopod large compared to rami; about
round in cross-section; distal margin (where rami attach) forming
acute angle with medial margin, with circa 15 short setuled plumose
setae on ventral margin (10 in manca 3) and circa 15 long setuled
plumose setae on dorsal margin (5 in manca 3).
Endopod short and
stubb,y, length 0.33 times medial length of protopod in manca 3; distal
tip with tuft of broom and short setule plumose setae.
hopod about
halt length of endopod, with distal tuft of short setuled plumose
setae.
187
\ , I ,/
ｾＢｉ＠
-,r,l'
.."·
ｩＮｾ＠
ｾ＠
"
"
'1
• It
!\
A '\',
·,
'.'\fL':
·· ,
.: I:
"
·
"
: ｾ＠Ｚ "
I . ｾ＠
ｾｅ＠
8
c
\
Figure .3.4.
Pleopods trom aopulatory male, mOAL WS04.
A-C, pleopod
I, saale bar to right ot A is 0.5 mm long: A, ventral view, setae
shown on right side, some plumose setae indiaated by insertion points
only;
B, lateral view, setae omitted;
0, lateral view ot distal tip_
D-F, pleopod II: D, ventral view, some plumose setae indiaated by
insertion points only;
small arrows in D;
E, aontour ot ventral surtaae at position ot
F, endopod with stylet and exopod, dorsal view,
with enlargement ot stylet distal tip.
G-I, pleopods III-V.
188
Remarks.--Schultz (1976) considered abyssorum to be a member or
Echinozone Sars 1899 because it has biramous uropods and lacks
mandibular palps.
Amuletta abyssorum, however, is dirrerent rrom the
species or Echinozone in the rollowing major characters: lacinia
mobilis and molar process not reduced as in most ilyarachnids, coxal
plates large on pereonites 1-3, antennal scale absent, and no spines
-:.;.'
on dorsal surraces.
[Concerning this last character, Schultz (1976)
described Echinozone as possibly having dorsal spines tipped with
stout setae, i.e., pedestal setae: a diagnostic character or
Bathybadistes Hessler and Thistle 1975.
None or the species or
Echinozone (ibid, list on p. 157) has such setae.]
ｾ＠
The inclusion or
abyssorum in Echinozone would unnecessarily and unnaturally broaden
the detinition ot the latter genus.
Amuletta agyssorum is a large species, with adult body sizes
between 1.0 and 1.5 cm.
It is larger than any species in the
Ilyarachnidae and most species ot the Eurycopidae.
Species or
Betamorpha, and the Syneurycopinae sometimes approach 1 cm in length,
and Storthyngura pulchrum is known to exceed 3 cm (specimens in the
collection ot R.R. Hessler trom ott southern Calitornia).
-A.
agyssorum ralls in the middle or the size range or the large members
ot the Eurycopidae.
ｾ＠
agyssorum has been round only in the northeast Atlantic Ocean
despite the intensive deep-sea sampling that has been conducted in
most parts ot the Atlantic.
The species has a broad depth range,
2379-4829 m., suggesting it is somewhat eurytopic by deep-sea isopod
189
standards.
The geographic distribution of
greater than reported here.
ｾ＠
abyssorum may be much
agyssorum is about the same size as
ｾ＠
Storthyngura pulchrum, a species which also appears rarely in
epibenthic-sled samples but is taken abundantly in large trawls
(Martham, 1978; and personal observations).
specimens of
ｾ＠
Therefore, the paucity of
abfssorum may be due ':.to avoidance of the epibenthic
sled used to collect most of the Atlantic deep-sea samples we have
examined.
The gut contents of a large female specimen (!NCAL WS02) were
removed during dissection.
This material consists of amorphous
sediment and detritus, and many whole or partially broken calcareous
Foraminifera (roughly 20% by volume).
Their abundance in this
specimen's gut indicates that A. agyssorum may be actively selecting
Foraminifera as food items.
Some of the amorphous material could have
been agglutinating Foraminifera, which would quickly become
unrecognizable under the attention of the mouthparts and gastric mill.
Consumption of Foraminifera by deep-sea isopods may be more common
than has been reported until now.
We have often seen calcareous
forams in the guts of other Janiroidean genera, although not as many
as in the
ｾ＠
abyssorum specimen.
Furthermore, the abundance of
Foraminifera in the deep-sea (Thiel, 1975;
Bernstein et al., 1978;
Snider, et al., 1985) suggests that these protozoans should be an
important food source for isopods and other macrofauna.
190
ACKNOWLEDGMENTS
Thomas Bowman, United States National Museum, and Jacques Forest,
Museum national d'Histoire naturelle Paris, loaned the type-specimens
of Ilyarachna abfssorum needed for this study.
The manuscript was
reviewed by Robert Hessler, William Newman, Richard Rosenblatt and
Hans Thierstein, all of Scripps Instit'ution of Oceanography, and two
outside reviewers provided by the Journal of Crustacean Biology-.
The
INCAL material analysed in this study was sorted by the Centre
National de Tri d'Oceanographie Biologique, and the Laboratory at Oban
of the Scottish Marine Biological Association.
This work was
supported by National Science Foundation grant BSR 8215942.
We
sincerely thank these people and institutions for their part in this
research.
CHAPTER 4
AN OUTGROUP FOR THE MUNNOPSOID FAMILIES: PHYLOGENETIC ANALYSES OF
THE SUBORDER ASELLOTA AND THE SUPERFAMILY JANIROIDEA
INTRODUCTION
The ilyarachnoid Eurycopidae clearly belong among the munnopsoid
families, but how they should be classified in this group is uncertain
without knowing the ancestral state of the munnopsoids.
Knowledge of
the evolutionary sequence from primitive to derived in a taxonomic
group's characters is a primary requirement of successful phylogenetic
analysis. (Hennig, 1966).
The most successful technique for
determining this evolutionary sequence is outgroup analysis (Watrous
and Wheeler, 1981; Maddison et al., 1984).
In the following pages, the
results of several outgroup analyses of the Asellota will be reported
with the goal of finding the most likely sister group of the
munnopsoid families, Eurycopidae, Ilyarachnidae, and Munnopsidae.
With this knowledge, the systematic position of the ilyarachnoid
Eurycopidae may be determined.
In well-developed classifications,
broad ranging systematic work of the type reported here would be
unnecessary.
One simply would consult existing authoritative works
for the best estimate of the outgroups.
such works exist.
For the Asellota, however, no
Evolutionary relationships at the superfamily-level
191
192
are poorly resolved, and published studies of the asellotan taxa
generally do not use eonsistent phylogenetic techniques.
This ahapter
is a partial remedy to this situation, and is the springboard to the
work reported in the final chapter.
To aeeomplish the objeetives of this chapter, a new taxon, the
family Pseudojaniridae, is introdueec("into the elassification of the
Asellota, using morphologies overlooked by my eontemporaries.
The
Pseudojaniridae is important beeause this monotypic family has
eharacters that are elearly intermediate between the superfamily
Stenetrioidea and the superfamily Janiroidea.
contains the munnopsoids.
The latter superfamily
At the superfamilial level, the morphology
of the cutieular organ, a female copulatory organ, was found to be
very useful for aseertaining the evolution of the Janiroidea.
Within
the Janiroidea, the third pleopod and the seemingly insignificant
claws on the pereopodal dactyli are used extensively.
All these
eharacters are described below and their evolutionary polarities are
determined.
These data are then used in two phylogenetic analyses,
one at the superfamilial level of the suborder Asellot& and one at the
familial level of the superfamily Janiroidea.
MATERIALS AND METHODS
SPECIMENS
The holotype female and male speeimen of Pseudojanira
stenetrioides were kindly loaned b.1 M.G. van der Merwe, Marine Biology
Technieal Offieer of the South African Museum (SAM).
The accession
193
numbers for these two specimens are SAM A6295 and SAM A15345,
respectively.
The holot;rpe female was collected off the Zululand
coast, among coral found in the eulittoral zone.
comes from off South Africa (240 53'
at a depth of 55 m.
s,
The male specimen
340 56' E) in fine gray sand
The remaining examples of the genera discussed in
this chapter were taken from the research
collection of Robert
.-:.
Bessler.
The specimens of Munna, Paramunna, Notasellus and Santia
were collected at Palmer Station, Palmer Penninsula of Antarctica
(Richardson, 1976).
Lund, Sweden.
Asellus was collected by Robert Bessler near
The remaining specimens were collected in various
localities in the deep Atlantic Ocean by vessels of the Woods Bole
Oceanographic Institution.
For studies of the cuticular organ, the holot;rpe of Pseudojanira
stenetrioides was studied in lactic acid after staining with methylene
blue.
Other specimens were bisected sagittally, and one half of each
was macerated in potassium hydroxide solution kept at a temperature of
600 C.
After all tissues except the cuticle were dissolved away, the
specimens were either studied in lactic acid - methylene blue or were
stained in Ehrlich's triple stain (Guyer, 1953, p. 246), rapidly
dehydrated into 100 percent ethanol, and transferred to turpineol for
examination.
turpineol.
All macerated specimens are stained and stored in
The illustrations in this chapter were inked from pencil
drawings made using a Wild M20 microscope fitted with a camera lucida
drawing tube.
Previous discussion of the evolution of the Asellota
have t;rpically relied on simple outline drawings of limbs for
comparison.
The fine details of asellotan construction, however, are
194
otten phylogeneticall1 important (Wlgele, 1983).
For example, an
outline ot the endopod ot male pleopod II would not show the
ditterence between the stylet ot Pseudojanira and that ot the
J&n1roidea.
Theretore this chapter will provide more pictorial
intormation than has been typicall1 ottered in the past.
In the
illustrations ot body parts, and especially the cuticular organs,
anterior is toward the top ot the page.
DATA ON JANIROIDEAN CHARACTER STATES
Information on the character states ot the tamilies ot the
Janiroidea was taken trom many literatures sources.
A pictorial card
tile and these literature sources were used to survey the character
states used.
This card tile, compiled by various workers in Hessler's
laboratory, including me, contains photocopied illustrations trom the
literature ot a large proportion ot the Janiroidean genera.
Data on the dactylar claws ot the pereopods was derives trom a
survey ot these characters conducted by Robert Hessler, Bryan Burnett,
and me.
The intormation consists ot numerous polaroid photographs ot
scanning electron microscope images, arranged by taxon.
The images
are views trom ditterent directions ot the pereopod II dactylus ot
specimens trom most ot the Janiroidean tamilies, as well as trom the
Stenetrioidea and other isopodan suborders.
It no images ot a taxon
were available, the literature generall1 provided the needed data.
195
PHYLOGENETIC TECHNIQUES
Phylogenies were estimated primarily using techniques codified by
Hennig (1966), and explained in modified form by Wiley (1980).
Hennig's method relies on knowledge of ancestral and derived character
states, from which the taxa are arranged in a hierarchical branching
sequence.
Parsimony is the
｣ｲｩｴ･ｯｮｾ＠
..for arranging the taxa; this
criterion chooses an estimated phylogeny that hypothesizes the fewest
total changes in character states from the observed distribution of
character states among the taxa.
Using such a criterion allows one to
derive phylogenies in those cases where several sets of characters
provide conflicting estimates of the true phylogeny.
This form of phylogenetic estimation relies on knowledge of the
polarity of the characters, that is, which character states are
ancestral or plesiomorphies and which are derived or apomorphies.
A
series of character states from ancestral to derived is called a
transformation series.
The most reliable way of determining the
polarity in a transformation series is to use outgroup analysis
(Watrous and Wheeler, 1981 j Maddison et al., 1984). Watrous and
Wheeler (1981) give a simple rule for determining polarity: for a
character with 2 or more states within a taxon, the state found in
that taxon's most closely related group, the sister group, is the
plesiomorphy within the taxon.
Maddison, Donoghue, and Maddison
(1984) point out that this rule fails when the characters vary in
potential sister groups.
They advocate the use of an algorithm that
uses an estimate of the phylogeny of the all the taxa, both outgroups
and the ingroup, to assign the most parsimonious estimate of a
196
character state to the outgroup node (the ancestral species of the
sister group and the ingroup).
Once the ancestral states are known
from this procedure, the phylogeny of the ingroup can be estimated.
Maddison et ale (1984) show that this two step procedure can achieve
the most parsimonious estimate ot the phylogenr for both the outgroups
and the ingroups, a quality they call:'" global parsimony. n
A phylogenetic tree, here considered the same as a cladogram, may
be constructed using the logical rule ot parsimony, although one
cannot be certain that
!!! the most parsimonious trees have been
investigated for cases that have more than a few characters and taxa.
Numerical techniques tor evaluating phylogenies are useful when the
complexity ot the data set exceed one's ability to find all possible
•
trees.
For the work reported here, both logical and numerical
techniques were used to estimate phylogenies.
essentially the same results.
Both methods yielded
The numerical methods also give
parsimony values and trees automatically, allow the testing the effect
of various topologies of transformation series, arid give results in a
few minutes rather than hours of careful work.
The numerical methods used here were developed by Joseph
Felsenstein, University of Washington, and colleagues, and are
supplied by him as PASCAL programs that may be easily compiled into
machine language for many different kinds ot computers.
The programs,
called PHILIP (PHYlogeny Inference Package), use a variety of
algorithms for determining phylogenies, discussed in Felsenstein
(1979; 1982).
The programs were moditied by me to run on an
197
International Business Machines XT microcomputer, and turned into
machine language by a compiler, Turbo Pascal, distributed by Borland
International.
The PHILIP program used most heavily for my analyses was MIX,
which allows the use of weights and two different parsimony algorithms
ｾ＠
for each character separately_
The two algorithms are the Gamin-Sokal
method (Gamin and Sokal, 1965) and the Wagner method (Eck and Dayhoff,
1966; Kluge and Farris, 1969).
The assumptions of these methods are
stated in Felsenstein (1978, 1979, 1981).
Both methods assume that
characters and lineages evolve independently, that the evolutionary
rates are sufficiently low that any change in character state is
unique, and is unlikely to be duplicated in another lineage for the
taxa under consideration, and that retention of polymorphism is less
probable than a change from an ancestral (state 0) to a derived state
(state 1).
The most important difference between the two methods is
that the Gamin-Sokal method does not allow reversions, and the Wagner
method does.
The Wagner method also does not assume an ancestral
state, whereas the Gamin-Sokal method requires knowledge of the
ancestral state.
In the analyses, however, the ancestral state was
generally given for either method to "root" the trees.
The program MIX operates by taking the first three taxa from the
taxon-character matrix given, and finding a most parsimonious tree for
the distribution of characters and the assigned parsimony methods.
It
then sequentially adds taxa to the tree by placing each one on the
branch between nodes that adds the fewest changes in character states.
198
This process is continued until all the taxa are assigned branches on
the tree.
data.)
(See appendix 2 for example of program output for Asellota
This algorithm does not investigate all possible tree
topologies because the number of trees quickly becomes astronomical
even with a few taxa. (Felsenstein, 1982).
As a consequence, MIX is
sensitive to the input order or the taxa and must be run numerous
times with different orderings.
This process was automated by writing
a PASCAL module for MIX that randomly orders the taxa. into as many
data sets as desired, and then runs the program iteratively until all
the data sets are evaluated.
This method proved to be most effective
because after the new program, lTERMIX, was started, it could run
automatically for long periods of time without user intervention.
Typically, "a" most parsimonious tree was found within 10 iterations,
but often different topologies with the same low value appeared in
runs of 30 or more iterations (see appendix 2).
Some of the characters had uncertain transformation series.
This
made it necessary to do multiple runs of the lTERMIX in order to test
all possible combinations of the uncertain transformation series.
These initial runs were done in the more restrictive Camin-Sokal
method, with an ancestral rooting of all the characters and no weights
for the different characters.
Fortunately, only three 3-state
characters had uncertain transformation topologies, and only 12
different data sets were tested.
Each of these data sets was run at
least 10 times, although the more promiSing combinations were run 3040 times.
This resulted in a ordering of the data with transformation
199
topologies that produced the single most parsimonious tree.
Character
weightings and mixed parsimony methods were added to the data set, and
the final version of the tree was generated.
This procedure was
,
necessary only for the data set of the janiroidean family-level
. groups, which contained IIl8llY conflioting characters.
The Asellota
data set oontained highly oompatible characters, so that every run
-:;.,).
produced preoisely the same result.
PHILIP also oontains programs that use radically different
methods for evaluating trees.
The one used here was CLIQUE, whioh
uses the oharaoter compatibility method (Estabrook, Johnson, and
MaMorris, 1976a, 1976b; Bron and Kerbosoh, 1973).
This method uses
two state discrete characters for which the ancestral state is
unknown, assumes that changes in character states occur only once, and
finds the tree that has the largest "clique" of compatible characters.
Compatible charaoters are those that do not produce oonflioting
estimates of the branching sequenoe of the phylogenetio tree.
This
method has been oritioized beoause it does not use all the data to
estimate a tree (Hill, 1975).
Here it proved to be ineffeotive in
generating well resolved trees for the data sets with a high degree of
homoplasy (or inoompatibility), and therefore was used only as a oheok
on the results of the Camin-Sokal and Wagner algorithms.
(See
Appendix 3 for results of CLIQUE runs on the two final data sets
assembled in this ohapter.)
200
A REDESCRIPTION OF PSEUDOJANIRA STENETRIOIDES BARNARD
INTRODUCTION
The discovery of unusual female and male copulatory organs in
Pseudojanira stenetrioides Barnard, 1925, made it necessary to include
a redescription of this unique animal.
f.
stenetrioides is a small
isopod from South Africa, recently redescribed by Kensley (1977) and
classified by that author as a member of the family Janiridae,
superfamily Janiroidea.
This species (fig. 4.1, 4.2) has a
stenetrioid habitus and a male first pleopod intermediate between the
conditions seen in the Stene trio idea and in the Janiroidea.
An
examination of 2 specimens of this species from the South African
Museum confirmed Kensley's figures (1977), and revealed the presence
of a new type of female genital organ which will be described in the
survey of asellotan cuticular organs.
characters found in
genus Pseudojanira.
f.
Because the combination of
stenetrioides, a new family is erected for the
The superfamilial classification, however, is
left undecided; proper determination of the superfamilies must be
based on a complete morphological survey of all the families of the
"lower" Asellota (see discussion after the phylogenetic analysis
below).
201
Figure 4.1.
male, 2.8
D.
Pseudojanira stenetrioides Barnard, 1925.
A, O-H,
B, holotype female, reported intact length 3
dorsal view, setae on right side omitted.
D.
B, dorsal view of female
pereonal fragment, co - position of cuticular organ seen through
dorsal cuticle, sp -,spermatheca seen through dorsal cuticle;
specimen was cleared with lactic acid and-:-'stained with methy'lene
blue to make this possible.
0, pereopod I of male, distal
segments only, with enlargement of opposing setation on propodus
and dactylus.
Carpus and propodus had many long tubular setae;
their insertions are indicated by 'u' or circular marks, and a
few are drawn in to give an approximate length of the ones
omitted.
Some of
ｴｨｾ＠
in the same manner.
setae in the enlargement are illustrated
D, ventral view of left side of cephalon
(right side had been dissected); I - antennula, II - antenna, r
- rostrum, m - maxilliped, mnd - mandible.
Note how the rostrum
is nearly as long as the antennula, the tip of which is
protruding past the basal articles of the antenna.
E, Ventral
view of male pereonite 7 and pleotelson, with pleopod I shown at
the same scale; I - pleopod I, II - pleopod II, III - pleopod
III, p - penile papillae, pl.1 - presumed pleonite 1, pl.2 presumed pleonite 2,a - anus, u - ,uropod.
F, dactylus of
pereopod mounted on slide, possible pereopod VII as in [ensley
(1977).
Note presence of 2 subequal claws and a more proximal
accessory seta on dactylus.
palp omitted.
A,
G, right mandible, dorsal view,
H, right antennula, ventral view.
202
203
ORDER ISOPODA, SUBORDER ASELLOTA, SUPERFAMILY mCERTAE SEDIS
PSEUDOJANIRIDAE NEW FAMILY
(Figures 4.1, 4.2)
Type-Genus.--Pseudojanira Barnard, 1925,
｢ｾ＠
original designation.
Previous Assignments ot Type.--Jaeridae:
Barnard (1925, p. 406).
-,,,,
Janiridae: Woltt (1962, p. 252); ｋ･ｮｳｬｾ＠
ｋ･ｮｳｬｾ＠
(1977, p. 251).
Ianiridae:
(1977, p. 253).
Diagnosis.--Asellota with broad pereonal tergites extending
and ventra1J.y', hiding coxae from dorsal view.
Cephalon with dorsal
eyes, broad lateral lappets, and large frontal rostrum.
wi th
ｯｮｬｾ＠
Pleotelson
1 tree pleonite visible dorsally, 2 ventraJ.ly.
robust, with enlarged setose propodus;
opposi tion between
､｡｣ｴｾｬｵｳ＠
ｬ｡ｴ･ｲｾ＠
Pereopod I
grasping occurring by
and propodus; carpus short, quadrangular,
setose, not participating in grasping.
Male first pleopods fused at
basal segments, distal rami separate; distolateral corners with dorsal
grooves; distal margins quadrate, with simple setae.
Male pleopod II
basal segment enlarged, with endopod and exopod projecting
ｭ･､ｩ｡ｬｾ［＠
distal tip of basal segment enlarged, thickened, with transverse
distomedial groove supplied with fine setae; endopod distal segment
stylet-shaped, with open ventral groove and distolateral barbs;
endopod proximal segment with thickened cuticular ridge; exopod
comprising
ｯｮｬｾ＠
single short, robust segment, with thickened dorsal
hook on setose anterodistal corner.
not opercular.
Male pleopods I and II together
Female second pleopods (not seen by me) fused into
single opercular segment lacking setae on margins.
Pleopod III
204
exopod broad, rounded, with fringe of simple setae; endopod with 3
large plumose setae; in male, exopod opercular.
Uropods short,
biramous, setose, barely extending beyond posterior margin of
pleotelson.
Pseudojanira stenetrio1des Barnard, 1925
(Figures 4.1, 4.2)
Previous Descriptions.--Pseudojanira stenetrioides: Barnard (1925: p.
406-407); Kensley (1977, p. 251-253).
Holotype.--Adult female, 2 poorly preserved fragments (cephalon and
pereon), pleotelson missing, reported original length 3 mm, width 1.3
mm, SAM 6295.
Type locality:
"Zululand coast, in a coral (H.W. Bell-
Marley, 1920) ••• " (verbatim from original description, Barnard,
1925).
Additional Material.--Partially dissected adult male, with removed
limbs on a slide, length (including rostrum) 2.8 mm, width at sixth
pereonite 1.4 mm, SAM A15345.
Locality:
" ••• 240 53' S, 340 56' E,
55 metres, from fine gray sand" (verbatim from Kensley, 1977).
Description (in addition to familial diagnOSis Kensley, 1977).--Body
characters (fig. 4.1A,B): Lateral margins of pereonites oval in
dorsal view.
Body surfaces covered with fine setae.
Body
dorsoventrally thin but highly vaulted: tergites extending beyond main
part of body and angling sharply downward.
Pereonite 1 sexually
dimorphic, longer and more robust in males than in females.
205
Female Cuticular Organ (fig. 4.1B):
Described below in section on male
and female copulatory organs in Asellota.
Cephalon (fig. 4.1A,D): Rostrum anteriorly rounded; thin, broad, and
nearly as long as short antennulae; projecting anteriorly from frons,
below linear anterior margin of cephaI'ic dorsUDl.
broad, flattened, with small anterior spine.
Lateral margins
Eyes projecting
dorsolaterally from domed central portion of cephalon, positioned
roughly halfway between midline and lateral margins.
Pleotelson (fig. 4.1A,E): Broader than long.
Pleopodal cavity small,
width half width of pleotelson, cavity separate from anus.
Lateral
margins not denticulate, smoothly curving.
Antennula (fig. 4.1H): Very short, length approximately length of
antenna! segments 1-4, basal segment largest.
Broom setae on
segments 2 and 4; aesthetascs on distal three segments.
Antenna (fig. 4.1D): Basal segment :3 with large, unfused scale.
Right Mandible (fig. 4.1G): Spine row with 10 members.
Articular
condyle on dorsal surface distinctly shorter than length of robust
molar process.
Molar process with approximately 9 setae on
denticulate posterior circWllgnathal surface.
First pereopod (fig. 4.1C): Claw of dactylus opposing large spine-like
serrate seta on propodUB.
Row of small tapering setulate setae
leaning toward more posterior large spine-like seta.
Oppositional
206
margin of dactylus armed with row of short multiply-toothed setae.
Carpus and propodus with several dense groups of long, thin setae.
Dactylar claws of the walking legs (fig. 4.1F).
Distal tips of walking
legs with 2 robust claws of similar size, and more proximal small
claw-like accessory seta.
Male Pleopod I (fig. 4.2A,B): Length 0.42 pleotelson length,
distal segments covering rami of pleopod II.
medially.
Basal segments fused
Distal rami separate, distally quadrate with fringe of
simple setae posteriorly and laterally.
Dorsal side of distolateral
corners with stylet grooves (sg in fig. 4.2B).
Male Pleopod II (fig. 4.2C,D): Length subequal to pleopod I, with
endopod and exopod inserting in center of medial margin.
Distal tip
broad, curving laterally to acute angle, with setose groove in
.
posteromedial margin.
setae.
Lateral margin of basal segment with row of simple
Endopod proximal segment robust, with pronounced ridge on
ventromedial edge.
Endopod stylet present, with convoluted groove on
ventral surface and 4 small denticles on lateral margin of distal tip.
Exopod robust, powerfully muscled, with rounded hook and fine setae on
anterodistal edge.
Pleopod III (fig. 4.2E).
Exopod broad, fringed with simple setae,
covering pleopods IV and V; endopod somewhat less broad, dorsal to
exopod.
207
Figure 4.2.
Pseudojanira stenetrioides Barnard, 1925.
parts on slide from male paralectotype.
Dissected
A-B, pleopod I. A, ventral
view; B, dorsal (interior) view of distolateral corner; sg - stylet
groove.
O-D, pleopod II; 0, ventral view, exopodal musculature
shown through cuticle; D, enlargement of stylet: d - denticles, en endopod, ex - exopod, h - position of dorsally directed hook on
exopod, r - ridge on proximal segment of endopod, s - stylet (distal
segment of endopod), spg - sperm groove.
Note the ridge on proximal
segment of the endopod; this ridge allows the well-muscled exopod to
hook onto the endopod during copulation.
E-G, pleopods III-V,
respectively; plumose seta on pleopod IV enlarged.
208
-- ---
o
g
sg
/
I
-
209
Pleopod IV (fig. 4.2F):
Endopod broader than exopod.
Exopod with 2
free, laterally rounded segments, and 7 plumose setae on distal tip.
Pleopod V (fig. 4.2G):
pleopod IV.
Endopod longer and broader than endopod of
Basal segment and endopod fused, exopod absent.
DISCUSSION
The primary reason Pseudojanira stenetrioides must be placed in a
distinct family is that the male pleopods (fig. 4.2A-D) have a unique
combination of characters.
Because the current scheme of the
superfamilies of the Asellota is based on the pleopods, the forms of
these limbs in Pseudojanira make it difficult to place in the current
superfamilies.
The first male pleopod of Pseudojanira has a mix of
janiroidean and stenetrioid characters.
As in Stenetrium, the basal
segment is large, quadrate, and medially fused.
distal segment are free from each other.
The two sides of the
The distal tip, however, is
setose and the distolateral corners have deep, laterally-curving
grooves on the dorsal surface, clearly homologous the same structure
in the Janiroidea that functions as a guide for the stylet of the
second pleopod.
This determination of homology is made on the basis
of having the same position and functional relationship with the
stylet.
The form of the male second pleopod is interesting not only
in its similarity to the janiroidean condition, but also for
specializations that are seen only in this species.
Characters shared
with the Janiroidea are the pointed stylet, the ridge on the proximal
segment of the endopod, and the club-like hooked form of the exopod
with its enlarged musculature and distal group of fine setae.
210
However, the stylet has only a ventral groove and terminates with tiny
barbs, unlike any janiroidean.
The distal tip of the basal segment is
also highly unusual: it narrows distal to the exopod, and then
broadens both latera.1ly and medially.
Its distal tip is curved,
grooved, and covered with tiny fine setae.
stylet rests in the groove of the
｢｡ｳｾ＠
The distal portion of the
segment's tip.
It must
somehow function as an additional stylet guide, or perhaps as the top
part of an enclosed sperm channel.
The description of Pseudojanira states that one free pleonite is
visible dorsally (fig. 4.1A), and two ventrally (fig. 4.1E).
This
observation is made with some misgivings since the only specimen where
this could be studied had been damaged in the region of the ventral 2
pleonites.
re-examined.
If more specimens come to light, the pleonites should be
If true, it would be another character which places
Pseudojanira at an position intermediate to the Janiroidea (1 free
pleonite) and the Stenetrioidea (2 free pleonites, 1 reduced).
The chaetotaxy and form of the first pereopod requires special
mention: in many respects, they are similar to that seen in Stenetrium
(see fig. 4.128 for comparison), and in Gnathostenetroides.
Although
Wlgele (1983) makes a strong case for the similarity of the chaetotax.y
of the Stenasellidae, Atlantasellidae, and Microcerberidae (see his
figure 1, p. 253), some of the similarities may be plesiomorphies for
those taxa: many of the same types of setae are also seen in
Pseudojanira, Stenetrium, and Gnathostenetroides.
211
The accessory seta on the dactyli of pereopods II-VII is close
in position to the third accessory claw found in the janiroidean
family Janiridae and also in the Protojaniridae, and is nearly
identical in position to an accessory seta on the dactyl of the
Stenasellidae (see Magniez, 1974, p. 33).
This seta is presumed to be
homologous to the third claw of these,other groups, and could well be
a plesiomorphy of the Asellota.
212
THE FEMALE REPRODUCTIVE APPARATUS OF THE ASELLOTA
INTRODUCTION
There is some variety in the female reproductive morphology over
the various suborders of the Isopoda (Menzies, 1954; Ridley, 1983).
Current knowledge displays two seemingly different female reproductive
organs within the Asellota (fig. 4.3): fertilization through either a
ventral oopore on the fifth pereonite or a vagina-like anterodorsal
organ called a ".cuticular organ." Asellus, as an example for most of
the asellote superfamilies, has the typical fertilization site at the
ventral oopore (Maercks, 1931; Unwin, 1920).
Within the oviduct,
which opens at the oopore, there is a spermatheca that receives the
sperm and hold it untU release of the eggs.
A dorsal cuticular organ
is found only within the asellote superfamily Janiroidea.
This
bilaterally paired organ consists of an opening and an often complex
cuticular tube that leads to a spermatheca in the oviductal tissues.
It opens on the anterodorsal surface of the fifth pereonite (Sixth
thoracic segment), although the exact position of the organ varies
somewhat among the various taxa in the superfamily.
The existence of
this structure has been known for some time (Forsman, 1944; Wolff,
1962; Veuille, 1978b; Lincoln and Boxshall, 1983), although only
recently has the cuticular organ and its behavioral function been
carefully described (Veuille, 1978b).
213
Figure 4.3.
Asellota.
Previous oonoepts of female reproduotive organs in the
Diagrammatio oross seotions of two Asellota showing
literature oonoepts of the morphology of the female reproduotive
system in Asellus and the Asellidae (A) and in Jaera and the
superfamily Janiroidea (B).
Illustrations derived from Ridley (1983).
As will be shown, Asellus and other non-Janiroidea also have a
outioular organ, but it is positioned adjaoent to the oopore. The
outioular organ of lower Asellota is more diffioult to see beoause it
is buried in the tissues of the oviduot.
214
OVARY
_, ＬＭＮＺｾｓｐｅｒｍａｔｈｃ＠
ｾｏｖｉｄｕｃｔ＠
OVARY
B
ＭＢＧｾｏｒｇａｎ＠
CUTICULAR
ｪｾＺＢＧｓｐｅｒｍａｔｈｃ＠
OVIDUCT
OOPORE
215
How did a single oritice temale reproductive system evolve into a
two orifice S,ystem, separating the two tunctions?
Veuille (1978b)
suggested that an intermediate situation might be a "traumatic
insemination" in which the male uses its needle-like stylet (sperm
transterral organ) on the second pleopod to break: the surtace ot the
temale's cuticle and inject the sperm.into the spermatheca ot the
oviduct; he noted this type ot insemination occurs in some insects.
Fortunately, the solution to this problem is much simpler than the
hypothesis suggested b.Y Veuille: all temale Asellota have a
cuticular organ that connect to a separate spermatheca.
As seen
below, the cuticular organ ot the lower Asellota is adjacent to the
oopore and buried inside the tissuesot the oviduct.
Thus it cannot
be seen until the oviductal tissues are removed by potassium
hydroxide maceration.
Another question concerns whether the
cuticular organ evolved in unison with the specialized male genital
organs characteristic ot the Janiroidea.
This section provides data
tor these problems, the answers to which will be evaluated atter
adding information trom other characters in the next section.
216
TABLE 4.1. Taxa of Asellota examined for presence and position of the
cuticular organ. An n*n marks a literature report of a cuticular
organ. Abbreviations: nvn , cuticular organ is placed ventral and
opening adjacent to oopore, nDn, cuticular organ is placed dorsally,
opening distinctly separated from the ventral oopore.
GENUS
SUPERFAMIty AND
FAMILY
POSITION OF
CUTICULAR ORGAN
Asellus
Aselloidea, Asellidae
V
Stenetrium
Stenetrioidea, Stenetriidae
V
Pseudojanira
Superfamily Incertae Sedis
Pseudojaniridae n. fam.
V
Jaera *
Superfamily Janiroidea
Janiridae
D
Notasellus
Janiridae
D
Munna
Munnidae
V
Santia
Pleurocopidae
V
Paramunna
Paramunnidae
D
Abyssianira
Abyssianiridae
D
Acanthaspidia
Acanthaspidiidae
D
Eugerda
Desmosomatidae
D
Amuletta
Eurycopidae
D
Eurycope
Eurycopidae
D
Tytthocope
Eurycopidae
D
Dendrotion
Dendrotiidae
D
Dendromunna *
Dendrotiidae
D
Haploniscus *
Haploniscidae
D
Ischnomesus
Ischnomesidae
D
Macro styli s
Macrostylidae
D
Mesosieum
Mesosignidae
D
217
A SURVEY OF THE FEMALE REPRODUCTIVE APPARATUS
Veuille (1978) described the cuticular organ in janiroidean genus
Jaera.
It had been previously noted in the Haploniscus (Wolff, 1962),
and recently the organ has be described in Dendromunna (Lincoln and
Boxshall, 1983).
An inspection of specimens of deep-sea Janiroidea
shows the anterodorsally positioned
organ to occurs in most
｣ｾｴｩｵｬ｡ｲ＠
of the major families (see table 4.1).
Exceptions are the genera
Munna and Santia, in which the cuticular organ is ventral and
associated with the opening to the oviduct.
Various types of ventral
cuticular organs also occur in the non-janiroidean asellotes, such as
Asellus, Stenetrium, and Pseudojanira.
The major morphologies of the
cuticular organ from these taxa are described below.
Asellus (fig. 4.4).--The external appearance and configuration of the
female copulatory and egg-laying organ has been described by Maercks
(1931).
Because of its size, Asellus aguaticus proved to be an
excellent subject for study.
In an unmacerated specimen (as in fig.
4.4B), the cuticular structures are enclosed inside the tissues of the
much larger oviduct, and are not visible.
In the preparatory female
of Asellus, the cuticular organ opens on the anterior edge of the
oviduct's ventral attachment.
Internally the cuticular organ begins
as a tube surrounded by a fold of a cuticular pocket.
The tube
narrows and curves dorsally to connect with a large filmy sac, the
spermatheca, covered with parallel folds.
The spermatheca is so thin
that it cannot be seen unless the specimen is heavily stained with a
cuticular stain.
surface.
This sac has a large opening on its anterodorsal
218
Figure
4.4. The female reproductive system of Asellus. A, lateral
view of preparatory female of
!.
aguaticus.
A female in this stage
would mate during the next molt cycle after which the fertilized ova
would be released into the marsupium (made of plates extending
medially from the coxae of pereopods I-IV).
internal view of reproductive system.
B, semidiagrammatic
0, ventral view of pereonite 5
on a preparatory female, right side, showing location of oopore
(opening of the oviduct).
D, cuticular structure of oopore in
macerated, cleared, and stained preparatory female, showing structures
through ventral cuticle.
In the preparatory stage, the pocket is
closed by the cuticular surface.
During the molt to the brooding
stage when copulation takes place (after the posterior molt is cast
off, and before the anterior part of the body molts), the pocket
receives the blunt copulatory organ of the male.
Note the anterior
position of the opening to the cuticular organ (shown as a thin tube).
E, internal view of same structures as in D, showing pocket, cuticular
organ, and spermatheca.
The oviduct, which surrounds the spermatheca
and the pocket at its origin, is removed during the maceration process
that leaves only cuticular material.
cuticle.
The darkened area is the ventral
F, enlargement of the anterior junction between the pocket
and the cuticular organ, same view as E.
cuticular organ; ov - ovary;
cuticular pocket.
00 -
b - basis of pereopod V; c -
oopore; sp - spermatheca; p -
219
av
D
220
During mating, the pocket that covers the internal part of the
female oopore receives the male copulatory organ, the enlarged distal
portion of the male's pleopod II endopod (Maercks, 1931; see fig.
4.9A-B).
The motions made by the endopod during copulation (Maercks,
1931) would bring the opening of the cuticular organ in direct contact
with the sperm holding part of the end.0pod.
At this point,
presumably, the sperm would be released into the cuticular organ.
Stenetrium (fig. 4.5) .--The cuticular organ is not developed in
preparatory females, and was seen only in brooding females of
Stenetrium dagama.
This probably means that fertilization takes place
only immediately after the molt of the posterior half of the
preparatory female, and before the molt of the anterior part when the
oostegites would be deployed.
(Maercks, 1931).
Asellus has similar mating habits
In the brooding female, the cuticular organ opens at
the posteromedial edge of the oviduct's ventral attachment.
Internally, the organ is directly connected to an pocket at the
opening of the oviduct.
A short tube connects the cuticular organ's
orifice to a thin sac, which is confluent with the oopore pocket.
Although the pocket and spermatheca are attached, they may be
homologous with that of Asellus, because they are similar in location.
221
Figure 4.5.
female.
Female reproductive system of Stenetrium, brooding
A, ventral view of pereonite 5, right side, showing position
of oopore.
b, enlargement of oopore area.
organ visible through cuticle.
Note tube of cuticular
Also note that cuticular organ opening
has a more medial position than in Asellus.
C, internal view of
oopore region showing cuticular organ, pocket, and spermatheca
attached as single unit.
cuticular organ;
spermatheca.
00 -
b - basis of pereopod V; co -
oopore; p
ｾ＠
cuticular pocket; sp -
222
8
co
sp
223
Pseudojanira (fig. 4.6).--Because only the preparatory female holotype
of Pseudojanira stenetrioides was available, a macerated specimen of
this species was not examined.
However, the female did clear well in
lactic acid, which allowed the inspection of the cuticular organ close
to the ventral surface.
The cuticular organ opens on the anterior
edge of the attachment of the oviduct to the ventral cuticle, and is
.;.
adjacent to a cuticular fold that is, in effect, a blind tube just
below the ventral surface.
This closed tube opens anteriorly to a
groove in the anteroventral edge of the fifth pereonite that curves
dorsally.
The opening of the cuticular organ is surrounded by a
bulbous, thickened funnel that appears to open almost directly into a
large spermathecal sac.
The cuticular organ is also positioned
anterior to the oopore and is almost separate from it.
This could be
an intermediate state to cuticular organ-oopore relationships seen in
the lower Asellota and the Janiroidea, although the dissimilarity of
the Pseudojanira female organ makes the homologies uncertain.
The
spermatheca protrudes posteriorly into the sixth pereonite and was
observed to contain translucent, heavily staining material similar to
sperm masses seen in other species of Asellota.
There is a pocket-
like structure beneath the external position of the oopore but it is
much smaller that that seen in Asellus or Stenetrium.
Figure 4.6.
female.
Female reproductive system of Pseudojanira, preparatory
A, semidiagrammatic dorsal view of the reproductive organs,
showing what they would look like if the dorsal surface of the pereon
were removed.
broken off.
Anterior is to the right, cephalon and pleotelson
B, ventral view of pereonite 5, left side, showing oopore
region and spermatheca through the ventral surface.
oopore region showing structures beneath the cuticle.
0, enlargement of
ov - ovary;
00
- oopore; co - cuticular organ; sp - spermatheca; sr - stylet
receptacle; b - basis of pereopod V truncated (shown only partially).
225
sr
---
-:J?
00
co
8
ｳｰＭｾ＠
".
c
".
226
Mating has not been observed in Pseudojanira as it has been in
Asellus (Maercks, 1931) or Jaera (Veuille, 1978a), although the
configuration of the male and female sexual organs suggests their
function (see fig. 4.9E).
The closed tube adjacent to the opening of
the cuticular organ is approximately the same diameter on the inside
as the outside diameter of the tip of the male stylet on pleopod II.
ｾＧＢ＠
If the stylet were inserted into the tube, the groove in the stylet
would be adjacent to the opening of the female's cuticular organ.
Therefore, I assume that this closed tube is a stylet receptacle, and
will refer to it as such in this paper.
The barbs on the stylet tip
would help hold the limb in place while sperm transfer takes place.
An alternative hypothesis, the insertion of the stylet directly into
the tube of the cuticular organ, seems less likely since the barbs of
the stylet potentially could damage the tissues of the spermatheca and
oviduct.
The stylet receptacle may not be homologous with the oopore
pockets seen in Asellus and Stenetrium, because a reduced pocket is
inside of the oopore.
Munna (fig. 4.7).--A large preparatory female of Munna antarctica
showed a well-developed cuticular organ.
The opening of the organ is
in about the same position as was found in Stenetrium, the
posteromedial corner of the oviduct's attachment point.
The cuticular
organ is not associated with any surficial cuticular folds or pockets,
other than two cuticular thickenings extending anteriorly and medially
from the organ's opening.
The tube of the organ is long and
227
Figure 4.7.
The
ｴ･ｾ＠
reproductive system ot Munna, preparatory
temale.
A, ventral view ot pereonite 5, right side, showing oopore
region.
B, enlargement ot oopore region showing cuticular organ
beneath ventral surtace.
Note that the cuticular organ is adjacent to
the oopore opening and is positioned somewhat posteriorly. No pocket
was apparent beneath the cuticle covering the oopore.
- cuticular organ, b - basis ot pereopod V.
00 -
oopore, co
228
A
00
B
229
terminates without any cuticular sac for the spermatheca, similar to
all Janiroidea examined
ｾ＠
me (see table 4.1).
Therefore, the
spermatheea must be a fleshy sac enclosed in the tissues of
the oviduct, as in Notasellus (see below).
Female specimens
of Santia mawsoni showed a similar configuration of the
cuticular organ.
ＧＮ［ｾ＠
Because the male stylets of the Pleurocopidae and Munnidae have
hollow tubes extending to their tips, members of these taxa probably
mate by inserting the stylet directly into the long tube of the
cuticular organ.
This would be in accord with what is observed in
Jaera, although the openings to the cuticular organ are in completely
different locations in the two taxa.
Notasellus (fig. 4.8).--A large preparatory female of Notasellus
sarsi provided an excellent lactic acid cleared preparation of the
cuticular organJ therefore this organ can be described in somewhat
better detail than in the above taxa.
In potassium hydroxide
macerated and stained specimens of Notasellus, the cuticular organ
is easily seen to open on the anterodorsal part of the fifth
pereoni te.
The opening is actually in the articular cuticle
between the fifth and fourth pereonites.
The cuticular organ
starts as a small funnel and continues anteriorly as a long, thin
tube.
At its internal end, the tube has a
usn
shaped bend.
In
the lactic acid cleared specimen, the cuticular organ is imbedded
in the tissues of the oviduct.
These tissues form a "Y" shape
230
Figure 4.8.
Female reproductive system of Notasellus.
ventrolateral view of preparatory female
ｾｴｨ＠
organ opening areas on pereonite 5 darkened.
A,
oopore and cuticular
B, diagrammatic view
through cuticle of the reproductive system, enlarged compared to A.
0, internal medial view of reproductive system.
Note that the
oviductal tissues form a "Y" shape, with one end attaching to the
oopore, one end surrounding the cuticular organ, and one end
containing the spermatheca and attaching to the ovary.
D,
enlarged ventral view of spermatheca seen through the
tissues of the oviduct, showing the "S" shaped distal end of
the cuticular organ and its attachment to the spermatheca.
The spermatheca seemed to be made of several layers and
between two of the layers at the posterior end was a small
bit of cuticular tube, possibly a remainder of the cuticular
organ from a previous molt (many large Asellota are
iteroparous).
00 -
oopore, oc - opening of the cuticular
organ, od - oviduct or tissues of the oviduct, co cuticular organ, sp - spermatheca, p4 - internal surface of
pereonite 4, p5 - internal surface of pereonite 5, p5a articular region of pereonite 5 (see how the cuticular organ
opens at the extreme anterior edge of pereonite 5).
231
p5
p4--=-==
ｾ＠
00
o
od
232
with two ot the ends attached to the external cuticle at the opening
to the cuticular organ and to the ventral opening ot the oviduct.
third end opens into the ovary in the tourth pereonite.
The
The sheath ot
oviductal tissues surround the tube ot the cuticular organ tor its
entire length, including the parts ot the tube inside the walls ot the
oviduct.
Atter entering the oviduct" ..,..the tube and its sheath ot
tissues bend sharply to the posterior and then curve under the body ot
the spermatheca, which is also inside the oviduct.
opens into the spermatheca on its ventral side.
The cuticular tube
The tissue sheath ot
the cuticular organ appears to become part ot the spermatheca at this
point.
Veuille (1978b)
､ｾｳ｣ｲｩ｢･＠
a two-layered spermatheca trom thin
histological sections ot the temale reproductive organs.
He showed a
primary spermatheca surrounding a smaller sac ot the secondary
spermatheca.
ot structures.
Jaera and Notasellus are likely to have the same types
Theretore his primary spermatheca may be the same as
the wall ot the oviduct, and his secondary spermatheca is the true
spermathecal sac which is inside the lumen ot the oviduct.
CHARACTER STATES OF THE CUTICULAR ORGAN
The above survey ot the cuticular organ within the Asellota shows
that this complex structure is not a detining synapomorphy ot the
Janiroidea, because it occurs in other supertamilies ot the Asellota,
i.e., the Aselloidea and the Stenetrioidea.
Theretore, the question
ot how the cuticular organ developed is set to a higher systematic
level.
The distribution ot this structure in the Isopoda and other
233
Peracarida is of considerable interest but is outside the scope of
this paper.
Here, the relationship of the Janiroidea with the other
superfamilies of the Asellota is the primary concern.
Because the distribution of the cuticular organ outside the
Asellota is unknown and because the sister group for the Asellota is
yet to be determined, it will not be -pOSSible to assign polarities to
the transformation series derived here for the cuticular organ.
I
prefer the condition seen in Asellus as the plesiomorphic state of the
cuticular organ.
This preference is based on the overall
plesiomorphic state in the Aselloidea of many of the characters used
in the next section, and on the fact that something as odd as the
dorsal cuticular organ would surely have been noted if it existed
outside of the Asellota.
The cuticular organ has two characters that may be used here for
phylogenetic analysis: the position of the opening of the cuticular
tube, and the manner in which the cuticular organ receives the male
copulatory organ.
Figure 4.9 diagrammatically shows the character
states found in three of the taxa studied.
The position of the cuticular organ's opening will be considered
here to have two states: the opening directly associated with the
opening of the oviduct and the opening on the anterodorsal surface of
the fifth pereonite.
The two character states could be further
subdivided into substates describing the exact position of the
cuticular organs with respect to landmarks on the fifth pereonite.
For example, in those taxa which have the cuticular organ associated
234
with the ventral oviductal opening, there are two substates: an
anterior position as in Asellus, and Pseudojanira (fig. 4.4, 4.6), or
a posteromedial position as in Stenetrium and Munna (fig. 4.5, 4.7).
Among the janiroidean families, the details of the cuticular organ
opening show considerable variation, from distinctly dorsal and set
well back trom the pereonite
｡ｲｴｩ｣ｵｬｾｯｮ＠
in the Dendrotiidae to a
position associated with the articular cuticle between pereonites 4
and 5 in Botasellus.
The distribution of this sub-character set is
poorly known and requires further research before it can be used in
phylogenetic analysis.
The interaction between the cuticular organ and the male
copulatory organ has potentially three character states.
In the
first, exemplified by Asellus (see Maercks, 1931) and Stenetrium, the
essentially club-shaped male organ is inserted into the cuticular
pocket adjacent to the opening of the cuticular organ (fig. 4.9A,B).
Pseudojanira has the second state in which the male copulatory organ
is stylet-shaped and inserts into a closed tube adjacent to the
opening (fig. 4.9E).
The insertion of the stylet directly into the
opening of the cuticular organ is the third state of this character
series (fig. 4.9C,D).
It is uncertain whether the character state
found in Pseudojanira is an intermediate between the aselloid state
and thejaniroid state, is derived from one of the other two states,
or is the ancestral state (although this is unlikely).
For
Simplicity, these character states are reduced to a binary character
pair: the male copulatory organ inserted into an organ adjacent to the
cuticular organ or inserted directly into the cuticular organ.
235
Figure 4.9.
Mating in the Asellota.
atter Maercks (1931).
A-B, Copulation in Asellus,
A, semidiagrammatic cross-section views of male
(above) and female (below) pereonites 5
view.
､＼ｾｩｮｧ＠
copulation, posterior
Darkened left pleopod II of male, shown behind right tergite of
female, is inserting into right oopore region of female.
B, enlarged
view of right oopore region, showing how the endopod of the male fits
into the pocket and presses close to the opening of the cuticular
organ.
G-D, Copulation in Jaera, after Veuille (1978a).
C, male
astride female, inserting stylet of pleopod II into the opening of the
cuticular organ.
The pereopods of the female are omitted for clarity.
(Veuille (1978a) was able to observe this by pouring liquid nitrogen
on a copulating pair, and then thawing the specimens in fixative.)
D,
diagrammatic view of copulation, showing how the stylet inserts into
the cuticular organ.
E, Copulation in Pseudojanira (hypothetical).
If the stylet were placed into the stylet receptacle, it would be held
in place while the sperm flowed from the penile papillae (not shown)
along the groove in the stylet to the opening of the cuticular organ
adjacent to the oopore.
cuticular organ,
00 -
stylet receptacle.
en - endopod; ex - exopod, st - stylet, co -
oopore, p - pocket, sp - spermatheca, sr -
o
ｾｯ＠
ﾷＢＧｔｦＮｾｴｩ［Ｌ＠
co
ｾ＠
__ en
....ｾ･＠
I
•
st
co
.'
..
/
/
---------
,
sP
I
237
CHARACTER ANALYSIS OF THE ASELLOTAN SUPERFAMILIES
INTRODUCTION
To determine suaaessfully the polarity and transformation of
aharaaters within the Asellota, the immediate sister group of the
Asellota should be determined.
This presents a problem, however,
beaause no detailed phylogeny of the fsopoda has been attempted.
Numerous opinions as to general relationships have been published.
For example, Kussakin (1973, p. 21) wrote ItAsellota probably
originated from the anaient Pbreatoiaidea. 1t
The newest suborder,
Calabozoidea, has been aonsidered most alosely related. to the Asellota
(van Lieshout, 1983), although this taxon is speaialized and has a
number of reduaed features.
In addition, the Calabozoidea were not
aompared with the Pbreatoiaidea, leaving van Lieshout's analysis
somewhat weak.
A phylogenetia analysis of the Isopoda is well beyond
the saope of this work, sinae the aim here is to understand the
evolutionary structure within the Janiroidea by analyzing the
superfamilies of the Asellota.
Therefore many of the arguments below
will rely on the common or prevalent form of a partiaular aharaater
over all the suborders of the Isopoda in aomparison with the Asellota.
This may not be as weak as it seems beaause many of the general
aharaaters, such as the form of the first pereopod or the male
pleopods, recur in all the suborders.
238
SUPERFAMILY CLASSIFICATION AND TAXA USED
The classification used here is that of Bowman and Abele (1983)
with the following corrections and emendations.
The superfamily
Protallocoxoidea is not valid and should not be included in fUrter
classifications of the Asellota (Sket, 1979;
Wilson, 1980). Wlgele
(1983) presented the families Gnatpos'ti..enetroididae andProtojaniridae
as belonging to separate superfamilies; his usage is followed here.
The superfam!lial taxa used, then, are the Aselloidea, Stenetrioidea,
Gnathostenetroidoidea, Protojaniroidea, Pseudojanira (superfamily
incertae sedis), and Janiroidea.
three groups of families.
Within the Janiroidea, I recognize
These are: (1) Munnidae and Pleurocopidae,
(2) Paramunnidae and Abyssianiridae, and (3) the remaining families.
In the previous section, the Munnidae and Pleurocopidae were shown to
have a autiaular organ positioned differently than in the remainder of
the janiroideans (see table 4.1).
As is shown below, the form of the
first pereopod also allows one to separate the Paramunnidae and the
Ab,yssianiridae from the remainder of the Janiroidea.
THE CHARACTERS AND THEIR STATES
Although the evolution of the cuticular organ is useful for
determining large phylogenetic patterns within the Asellota, more
characters must be introduced in order to fully evaluate these
patterns.
The characters used here are those introduced as useful b,y
previous workers with some new additions.
Hansen (1905) demonstrated
that the pleopods help form a natural arrangement of the asellotan
families.
His results were amplified by later workers (Amar, 1957;
Fresi et al., 1980; Wlgele, 1983).
Because the male and female
239
anterior pleopods of the Asellota are strongly dimorphic, they will be
considered separately.
The complexity of the male pleopods provides
several characters, which are surprisingly independent of each other.
The variation in the third pleopod is diseussed but will not be used
in the phylogenetic estimate.
A comparison of the first pereopod in
a large number of isopodan taxa, both-of the Asellota and nonAsellota, has revealed that the overall formation of this limb is
similar across all the suborders of the Isopoda, but varies wi thin the
Janiroidea.
A decisive character state pattern in the form of the
first pereopod discovered during an analysis of the families of the
Janiroidea is also used.
Overall, a small number of character are
introduced into this analysis, so any conclusions drawn below must be
considered preliminary.
More characters could not be used because
many key taxa, such as Protojanira, are very poorly described, and
specimens were not available.
Male pleopods I (fig. 4.2, 4.10, 4.11).--The male pleopod I through
all Asellota is similar: paired Uniramous, and typically small limbs.
At the level of the Isopoda, this is a apomorphy since most of the
suborders have biramous first pleopods.
In the Calabozoidea, the
pleopods I are essentially uniramous, although there is a rudimentary
endopod (Van Lieshout, 1983).
The least modified state of the pleopod
I in the Asellota, as exemplified by Asellus, are uniramous, twosegmented limbs (fig. 4.10A).
Although both sides of the paired
240
Figure 4.10.
Male copulatory organs in tw.o Asellota.
A-C, Asellus,
A, drawn from specimen in collection, B-C, after Maercks (1931).
ventral view of pereonite 7 and pleotelson of male.
pleopods I.
B, enlargement of
Note that the basal podomeres are separate.
enlargement of right pleopod II.
A,
C,
Note that the endopod of pleopod II
(en) has a large internal pocket (indicated by dotted line) for
transmitting the sperm placed there by the elongate penile papillae
(pp).
D-E, Stenetrium.
of male·.
D, ventral view of ｰ･ｲｯｮｾｴ＠
E, enlargement of pleopod II.
7 and pleotelson
The stenetriid male endopod
lacks the internal pocket seen in the asellids, but has fine cuticular
combs and spines on the distal tip, apparently for holding the setae
f,or transfer.
(No one has reported mating in a stenetriid.)
the musculature to the exopod of both groups.
Compare
I - pleopod I, II -
pleopod II, III - pleopod III, pp - penile papilla, en - endopod of
pleopod II, ex - exopod of pleopod II, ur - uropod, p7 - pereoni te 7.
241
pp
p7
ｾＭｵｲ＠
E
--,.-en
ex
242
pleopods are not connected, they may be connected by coupling hooks on
the basal segment.
The first pleopods are small compared to pleopods
III-V, but they may cover the second pleopods.
The first pleopods of
Asellus take no part in sperm transmission, as the penes are brought
into contact with the endopod of the second pleopod for this purpose
(Maercks, 1931).
The tips of the
several tufts of setae.
ｦｩｲｳｾ＠
pleopods in Asellus also have
A modification of this form is the fusion of
the basal segments, so that both members of the pair are forced to act
together, thus eliminating the need for coupling hooks.
Fused basal
segments are found in Stenetrium (rig. 4.10D), Pseudojanira (fig.
4.2A), and the Janiroidea (fig. 4.11A,C).
Another set of character states is whether or not the left and
right sides of the first pleopods are completely fused, the basal
segments are greatly reduced, and a cuticular tube for sperm
conduction exists at the line of their fusion (see Veuille, 1978a; see
fig. 4.11A,C).
In asellotes that have this character complex, the
proximal end of the tube is a funnel into which the penes fit, and the
distal end opens on the dorsal side of the fused pleopods above the
distal segment of the second pleopodal endopod.
The presence of such
modified pleopods helps define the Janiroidea from all other Asellota,
those which have unfused distal rami of the pleopods I.
The latter
state is plesiomorphic since all the other suborders of isopods have
separate first pleopods.
243
Figure 4.11.
Male copulatory structures in several Janiroidea.
pleopods of Notasellus, ventral view.
ventral view.
A,
B, pleopod II of Notasellus,
C, pleopods I and II of Jaera, dorsal view, showing how
they operate together during copulation (after Veuille, 1978a).
In
this genus, the stylet grooves on the distal corners of pleopod I
(stg) extend laterally as closed "copulatory horns"; most Janiroidea
lack the copulatory horns but have the stylet grooves.
of Eurycope, a highly modified deep-sea janiroidean.
D, pleopod II
Note that this
pleopod is very similar in general detail to the two less modified
janiroideans.
Compare the size of the two opposing exopodal muscles
seen through the cuticle of D.
I - pleopod I, II - pleopod II, III -
pleopod III, en - endopod, st - stylet, sst - stylet sperm tube, ex exopod, pr - protopod (basal segment), r - ridge on proximal segment
of endopod where the exopod couples during copulatory movements.
244
B
c
D
........ - .....
245
A second character is found in the presence or absence of stylet
guides.
These guides are grooves on the dorsal surface of the tips of
first pleopods, which are somewhat broad and quadrate.
The stylets on
the endopods of the second pleopod fit neatly into these grooves,
which direct the motion of the stylets during copulation (Veuille,
1978a).
These features are seen only,.in Pseudojanira (fig. 4.2A,B)
and in the Janiroidea (fig. 4.11C).
The guides and function of the
stylet are intimately related to one another, implying that those taxa
that have stylet-like endopods on pleopods II but lack the guides must
mate in ways different from the Janiroidea and Pseudojanira.
The
dorsal side of the first pleopod also has a pair of cuticular tabs
which help lock the first pleopod in position between the two second
pleopods, effectively making both limbs operculiform.
This character
is apparently linked to the presence of the stylet guides, and
therefore is not independent.
Lack of the stylet guides is
plesiomorphic because nothing similar occurs in any non-asellotan.
The Gnathostenetroidoidea and the Protojaniroidea have male
first pleopods that are different from other Asellota: they are large,
broad, and lamellar.
Other Asellotes have male first pleopods that
are either small or narrow, and all are generally thicker.
The large
lamellar first pleopods are assigned the apomorphic state although the
true ancestral state is unknown.
246
Male Pleopods II (fig. 4.2C,D; 4.10C,E; 4.11B-D).--The primitive
condition for the male asellote pleopod II is well established
(W!gele, 1983), although the phylogenetic significance of some of its
details has gone unnoticed.
Within the Asellota, the basal segment is
somewhat enlarged and muscular, and both rami have two segments each.
The endopod is geniculate, and is
elaborated either with a
､ｩｳｾ｡ｬｹ＠
groove or pocket for transferring the sperm.
The exopod and the
endopod have structures that allow them to couple and act in concert
during the copulatory act (e.g. Asellus, Maercks, 1931; Jaera,
Veuille, 1978a); the exact form of the coupling mechanism varies among
the asellotan taxa.
This interlocking of the endopod and exopod may
be homologous in all asellotan taxa because they all have elongated
and enlarged exopodal musculature, apparently for the copulatory
function.
The entire limb is as small as or smaller than the first
pleopod.
None of the taxa examined had all these features unmodified,
although this configuration is exhibited by the Stenasellidae (e.g.
Magniez, 1975) of the Aselloidea.
Non-asellotan taxa also have
copulatory male pleopods II but the derived form of this limb
described here found does not occur in any of them, especially the
linking of the exopod to the endopod for copulation.
The typical non-
asellotan male pleopod II is a biramous structure with a smaller basal
segment and more or less lamellar rami.
The endopod generally bears a
narrow, cylindrical, and blunt appendix masculina.
Whether the true
outgroup of the Asellota has two or one segmented exopods remains
uncertain because in some suborders (including the Calabozoidea) the
247
exopod is an unsegmented lamella, and in others, like the
Phreatoicidea or the Anthurida (which has a primitive pleonite and
telson configuration), the exopod has two segments.
The first character of the male second pleopod to be considered
is the exopod: whether it is made of one or two segments.
As just
;"'io
said, it is not certain which is the plesiomorphic state, although a
two-segmented exopod
ＨｦｩｾＮ＠
4.100) is favored because it is found in
the least modified asellotes and in the somewhat similar
Phreatoicidea.
This ramus is short and uniarticulate in Stenetrium,
Pseudojanira, and in the Janiroidea (fig. 4.20,D; fig. 4.10E; fig.
4.11B-D) •
In Pseudojanira, and in the Janiroidea, the exopod forms a blunt
hook that links with a groove in the proximal article of the endopod,
making the second character for the exopod the presence or absence of
the hook.
Because none of the non-asellotan taxa has a short, hook-
shaped exopod, the lack of this form is plesiomorphic.
The endopod displays divergent trends among the Asellota.
In
Asellus, both articles of the endopod are fused, although this ramus
retains its geniculate form (fig. 4.100); in the Stenasellidae and the
other superfamilies, the endopod remains biarticulate thus limiting
its usefulness here for phylogenetic analysis.
A more userul
character is the presence or absence of a stylet-like endopod.
Non-
asellotan taxa lack any of the endopodal specializations seen in the
Asellota, so it is difficult to establish the plesiomorphic state on
these grounds alone.
Some ontogenetic evidence, however, is provided
248
by the development of the stylet in juvenile male Janiroideans
(Hessler, 1970; Wilson, 1981).
At the first molt where the endopod of
male pleopod II is expressed, this ramus is an undeveloped, clubshaped process, sometimes with a groove on its distal ventral end.
Atter the maturation molt, the stylet becomes sharp distally, the
sperm tube develops, and the tube is open at its tip.
The ontogeny of
the male stylet in the Janiroideans thus suggests that the
plesiomorphic state is the club-shaped process, and the hypodermic
needle-like stylet of the Janiroidea is an apomorphy.
The distal
article of the endopod is elongate and pointed both in the Janiroidea
(fig. 4.11B-D) and in Pseudojanira (fig. 4.20), different from the
club-shaped limbs in Asellus and Stenetrium (fig. 4.10C,E).
A stylet-
like endopod is also seen in the Protojaniridae (Wlgele, 1983).
Another pair of character states can be derived from the form of
the sperm transmitting surface of the distal segment of the endopod.
All asellotes have either a pocket or a groove on this part of pleopod
II.
For example, in Pseudojanira, the stylet has an elongate groove
on the ventral surface (fig. 4.2D), and the Aselloidea have variously
formed pockets (fig. 4.10C).
In the Janiroidea, the groove has become
closed into a tube that opens on the bulbous proximal part of the
segment and on the distal tip only (fig. 4.11B-D).
The presence or
absence of this stylet sperm tube is useful in dividing the Janiroidea
from all the other Asellota.
The sperm tube is the apomorphic state
because sperm tubes have not been reported trom the endopod of the
male pleopods II of any non-asellotan taxon.
249
Pseudojanira has unique barbs on the tip of the stylet (fig. 4.
2D), could be either a synapomorphy of this taxon, or an intermediate
state in the evolution of the Janiroidea.
Here it is assumed to be a
synapomorphy.
Female Pleopod II.
In the AselloideaL the second pleopods are
separate, round, uniramous, and lamellar.
In other Asellota, the left
and right sides of the female second pleopods are fused into a single
shield-like structure, which mayor may not be opercular.
Although
the aselloid pleopods II are not biramous, they are most similar to
the condition seen in most non-asellotans in that the two sides are
not fused together.
Therefore the separate pleopods are the
plesiomorphic state and the fused pleopods are the apomorphic state.
Pleopod III and Opercular Pleopods.--Even though these characters are
not used in the analysis, it is necessary to discuss them because
others have considered them important factors in the phylogeny of the
Asellota.
W!gele (1983) presents arguments that the primitive third
pleopods of the Asellota are biramous structures each with two rami
(endopod and exopod) of similar size, but not covering the more
posterior pleopods IV and V.
On this basis, he divides the Asellota
into a Itjaniroid linelt in which pleopods I and II are opercular, and a
"aselloid line" in which pleopods III are opercular.
The janiroid
line included the superfamilies Janiroidea, Protojaniroidea and
Gnathostenetroidoidea, and the asello1d line with the Aselloidea had
the Stenetr10idea as an offshoot unrelated to the ancestral
janiroideans.
The ancestor of the Asellota did not have opercular
250
third pleopods
!! ｾ＠
outgroup
ｾＬ＠
because pleopods I-V of all the
potential outgroups are large, biramous, lamellar, and nearly
similar.
The immediate ancestor of the Asellota, however, may have
had opercular pleopods III owing to their appearance in most of the
major taxa of the suborder.
This character state is a plesiomorphy of
...
the Janiroidea, because males of Notasellus and Jaera have it in a
form nearly identical to that seen in Stenetrium and Pseudojanira
(fig. 4.21; fig. 4.10D).
The opercular nature of the third pleopod is
lost in females of Notasellus and Jaera, and in all other Janiroidea.
Using the opercular function as a character could potentially
lead to confusion in developing a stable phylogenetic estimate of the
Asellota.
Because the character is one of function rather than of
morphology, convergence may be likely among the various groups.
For
example, Wlgele (1983) considers that pleopods I in the males of
Janiroidea and Gnathostenetroidoidea are similar because they are
opercular, even though the physical structure of these pleopods are
quite different.
Here opercular pleopods characters are not used to
avoid these problems, and the physical makeup of the pleopods is
considered separately.
First Pereopod (fig. 4.12).--The pereopod I (the second thoracic
appendage) proves to be valuable for differentiating major taxa in the
Asellota.
In most Isopoda and other Peracarida, this limb is a
grasping appendage with the opposing surfaces between the propodus and
Figure 4.12.
A, Asellus.
A comparison of the first pereopods of various Asellota.
B, Stenetrium, with enlargements of the setae on the
oppositional margins of the dactylus and propodus.
D, Munna.
C, Pseudojanira.
E, Notasellus, the basic form of the first pereopod for
most of the Janiroidea.
This figure demonstrates the evolutionary
transition in the first pereopod from the form seen in most Isopoda
where the dactylus and propodus can oppose one another (A-D), to the
form where the carpus and the propodus can oppose one another (E).
Munna is intermediate because the carpus is enlarged and can oppose
the movable dactylus along with the propodus.
the shape of the carpus (c) in these taxa.
propodus, c - carpus.
Compare the size and
d - dactylus, p -
252
253
dactylus.
The carpus is short, broad, and nearly triangular, and does
not take part in the grasping function.
The propodus and dactylus
typically have stout setae of various types, apparently to aid in the
grasping function.
Because this type of first pereopod occurs in all
non-asellotan taxa, it is the plesiomorphic state for the Asellota.
The plesiomorphic state is found in Asellus, Stenetrium, and
Pseudojanira.
Of the Janiroidea, only the Munnidae, Pleurocopidae,
Paramunnidae, and Abyssianiridae have a pereopod similar to the
plesiomorphic state, although modified in that the carpus is more
robust and has elongate stout setae which participate in grasping.
The propodus is somewhat reduced in these latter taxa.
The higher
Janiroidea have a pereopod I which closely resembles the more
posterior pereopods: the dactylus is short and stout, the flexure
between the dactylus and the propodus is restricted so that they do
not oppose one another, the propodus and the carpus are elongate, and
the carpus and propodus fully oppose one another.
The transformation
series derived here seems counterintuitive, because one would expect
the first pereopod of an isopod to resemble the more posterior walking
limbs in its most plesiomorphic state.
But because of similarities
of all non-asellotans, a grasping first pereopod is the plesiomorphic
state, and the walking leg form of the higher Janiroidea is the
apomorphic state at the level of the suborder Asellota.
Cephalic Rostrum (fig. 4.1A, D).--Many janiroidean taxa have a
cuticular projection on the cephalic frons between the antennulae
which is sometimes prominent and sometimes not.
This projection is
separate and distinct from the tergal cuticle of the cephalon.
A
254
homologous, prominent structure occurs in Stenetrium and in
Pseudojanira.
A similar rostrum does not appear in the Aselloidea or
in the primitive members of other isopodan suborders, although taxa in
these latter groups may have a rostrum-like projection of the cephalic
tergum.
Therefore the frontal rostrum of the Janiroidea is presumed
to be apomorphy shared with this superfamily and the Stenetrioidea and
Pseudojanira.
RESULTS OF THE CHARACTER ANALYSIS
The following is a list of the character states, their
transformations, and polarities derived above.
It also includes the
information from the section on the cuticular organ.
The distribution
of the character states among the taxa are shown in table 4.2.
1.
Cuticular organ opening ventral, adjacent to opening of oviduct
(0), or cuticular organ opening dorsal, separate from opening of
oviduct (1).
2.
Ancestral state not known.
Male pleopod II endopod tip inserted into female cuticular pocket
or closed tube adjacent to cuticular organ (0), or male pleopod
II endopod tip inserted directly into female cuticular organ (1).
Ancestral state not known.
3.
Male pleopods I basal segments separate medially (not fused) (0),
or male pleopods I basal segments joined (fused) medially (1).
255
4.
Male pleopods I distal segments separate medially (not fused)
without medial sperm tube (0), or male pleopods I distal segments
joined medially (fused) with medial sperm tube (1).
5.
Male pleopods I distal tips without dorsolateral stylet guides
(0), or male pleopods I distal tips with dorsolateral stylet
guides (1).
6.
Male pleopods I small or narrow, thick (0), or male pleopods I
large and lamellar (1).
7.
Male pleopod II exopod of 2 articles (0), or male pleopod II
exopod of 1 article (1).
8.
Ancestral state not known.
Male pleopod II exopod lobe-like, unelaborated (0), or male
pleopod II shaped like blunt hook, shape corresponding to groove
on proximal article of endopod (1).
9.
Male pleopod II endopod thick distally, not stylet-like (0), or
male pleopod II stylet shaped (1).
10.
Male pleopod II endopod distal tip without barbs (0), or male
pleopod II endopod distal tip with barbs (1).
The latter
character is seen only in those taxa with stylets.
11.
Male pleopod II endopod distal segment with open groove or pocket
(0), or male pleopod II endopod distal segment with tube opening
only on distal tip and more proximally (1).
256
12.
Female pleopods II separate and unfused medially (0), or female
pleopods II fused medially so that they form single shield-like
limb (1).
1.3.
Pereopod I dactylus long; dactylus and propodus with free
articulation and can oppose one another to participate in
grasping (0), or pereopod I dactylus short; dactylus and propodus
with restricted articulation and cannot oppose one another to
participate in grasping (1).
14.
Pereopod I carpus short and triangular; carpus and propodus with
restricted articulation and cannot oppose one another to
participate in grasping (0), or pereopod I carpus trapezoidal,
articulation between carpus and propodus only partially
restricted, can oppose one another by means of strong spine-like
setae or spines on carpus (1) or long and not triangular; carpus
and propodus with free articulation and £!a oppose one another to
participate in grasping (2).
15.
No rostral projection on cephalic frons (0), or cephalic frons
with rostrum (1).
257
TABLE 4.2.
TAXON-CHARACTER MATRIX FOR THE ASELLOTA.
The character
numbers correspond to those listed in text.
CHARACTERS
TAXON
1
2
3
4
5
6 7 8 9 10 11 12 13 14 15
Ancestor
?
?
0
0
.
0
?
?
0
0
0
0
0
0
0
0
Aselloidea
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Protojaniroidea
?
?
1
0
0
1
0
0
1
0
0
1
0
0
0
Gnathostenetroidoidea
?
?
1
0
0
1
0
0
0
0
0
1
0
0
0
Stenetrioidea
0
0
1
0
0
0
1
0
0
0
0
1
0
0
1
Pseudojanira
0
0
1
0
1
0
1
1
1
1
0
1
0
0
1
Munnidae-Pleurocopidae
0
1
1
1
1
0
1
1
1
0
1
1
0
1
1
Paramunnidae-Abyssianiridae 1 1
1
1
1
0
1
1
1
0
1
1
0
1
1
Higher Janiroidea
1
1
1
0
1
1
1
0
1
1
1
2
1
1
1
258
A PRELIMINARY PHYLOGENETIC ANALYSIS OF THE ASELLOTA
PREVIOUS PHYLOGENIES
Many implied phylogenies of the Asellota have been presented as
classifications, but only three works (Kussakin, 1973; Fresi et al.,
1980; Wlgele, 1983) display the relationships of the asellotan subtaxa
in explicit branching diagrams.
Kus-;ak1n (1973) and Fresi et ale
(1980) present the majority opinion on the evolution of the Janiroidea
based on previous classifications and their own work (fig. 4.13).
Their conception places the Stenetrioidea near the Aselloidea but on
the line leading to the Janiroidea.
These authors place the
Gnathostenetroidoidea (and the Protojaniridae) between the
Stenetrioidea and the Janiroidea.
Wlgele (1983), on' the other hand,
proposes that the Stenetrioidea belong on the aselloid line, which
includes the Aselloidea, and have a descent separate from the
ancestral janiroidean (fig. 4.14).
RESULTS OF THE PHYLOGENETIC ANALYSIS
A phylogeny for the Asellota different from the above two
concepts may be constructed using the characters discussed above
(table 4.2, fig. 4.15).
The taxa used are the superfamilies
recognized qy Wlgele (1983), with the exceptions that Pseudojanira is
added, and the Janiroidea are divided into 3 groups, the members of
which have the same distributions of characters used here: the
Munnidae and the Pleurocopidae, the Paramunnidae and the
Aqyssianiridae, and all the remaining families of the Janiroidea.
259
Figure 4.13.
Asellota.
Previous phylogenetic relationships proposed for the
A, Tree of Kussakin (1973).
B, Tree of Fresi et al (1980).
260
A
Denc:lrotiidae
\
I
Other Punilie.
IIUD1lidae- Pleurocopidae
""
/,BaPIOni.cida.
Bchinothambematidae - I lue
.
lanirellicla•
/'
Thamb.matida.'
IANIROmBA
GNATROSTBNBTROmOmBA
ｾｬＮｵｲｯ｣ｰｩ､｡･＠
Dendrotiidae
Santiida.
Echinothambematida.
8
lanirida.
Thambematiu.--...........
A..Wdae
ｇｎａｔｒｏｓｅｭｯｾＭ＠
PROTOIANIROmBA
STENET1UomEA
Stenasellida.
Figure 4.14.
(1983).
The proposed phylogeny for the Asellota of W!gele
His tree opposes previous concepts because the Stenetrioidea
are not in the clade containing the Janiroidea, but rather more
closely allied to the Aselloidea.
262
JANIROIDEA
PROTOJANIROIDEA
GNATHOSTENETROIDOIDEA
STENETRIOIDEA
Stenasellidae
ｾＭｍｩ｣ｲｯ･｢､｡＠
Alan tas ellidae
263
The similarities of the members of the first two groups are discussed
in Wilson (1980).
The third group, here called "the Higher
Janiroidea" merely for convenience, includes highly diverse families
and morphologies, and yet, at the systematic level discussed here with
the characters presented above, are all astonishingly constant.
The
relationships within the Higher Janiro.idea will be discussed in the
next section.
The tree (fig. 4.15) is very stable in its configuration,
regardless of whether Camin-Sokal or Wagner parsimony methods, or the
compatibility method are being used (see appendices 2, 3).
This is
primarily due to the almost complete lack of homoplasy, or conflicting
characters.
Only one character, the stylet-shaped endopod of the male
pleopod II must be derived twice.
DISCUSSION
At the superfamilial level, the proposed phylogeny resembles
those presented by Kussakin (1973) and Fresi et al. (1980), but the
Protojaniridae and the Gnathostenetroididae are placed before the
Stenetrioidea, because they lack the following apomorphies: frontal
rostrum, and single segmented male pleopod II exopod.
This phylogeny
conflicts with the superfamily concept of W!gele (1983), who commented
that "connections" between the aselloid line, which contained the
Stenetrioidea, and the janiroid line "are impossible."
Nevertheless,
placing the Stenetrioidea in the "janiroid line" and away from a close
264
Figure 4.15.
A new proposal for the phylogeny of the Asellota.
This
tree is similar to those proposed in the past except: 1. The
Protojaniroidea and Gnathostenetroidoidea are derived before the
Stenetrioidea.
2. The Stenetrioidea are not in the aselloidean clade
as proposed b,y W4gele (1983).
3. The new group represented by
Pseudojanira is added between the Stenetrioidea and the Janiroidea.
4. The Janiroidea are divided into three subclades. 5. The Janiridae
is not in the earliest derived group of the Janiroidea.
The numbers
marked on the tree are the apomorphies listed in table 4.2; note that
character 14 is a three state character and that the two derived
states are represented by 14 and 14', respectively.
Je.ll.irid.e. e
Dell.<b-otiid.e. e
ther li'altliU••
13
4b.YSSiall.irid.ae
' - - - - - Pe.re.tnUll.ll.id.ae
I, 14'
PleUl"OCOPidae
L ______ llull.lJ..fct".
5,8,9
266
relationship with the Aselloidea removes some of the potential
homoplaisies created by his proposed phylogeny.
The
second
ｦ･ｭ｡ｾ＠
pleopods of Stenetrium are fused into a single sympod, as in
Pseudojanira and the Janiroidea, an apomorphy not found in the
Aselloidea.
Also the reduction of the male pleopod II exopod to a
single segment is derived only once 1Ilstead of twice as in W8.gele's
scheme.
The unique genus Pseudojanira is placed at the outgroup node of
the Janiroidea because of the apomorphies shared with this superfamily
in the form of the male pleopods.
Two branching nodes separate
Paeudojanira from the higher Janiroidea and the Janiridae in which it
has been previously classified (Barnard, 1925; Kensley, 1977), forcing
a reconsideration of the correct placement of this taxon.
A large reorganization of the presumed evolutionary relationships
within the Janiroidea is necessary.
The clade including the
Pleurocopidae and the Munnidae is a sister group to all other
Janiroidean families; additionally, these families are further
subdivided by an early derivation of the ancestor of the Paramunnidae
and the Abyssianiridae.
The Dendrotiidae (and the closely related
Haplomunnidae) is a full-fleged member of the higher Janiroidea and is
not derived from a Pleurocope-like or a Santia-like ancestor as
suggested by Fresi et ale (1980) and Kussakin (1973), respectively.
In the phylogenetic schemes of Kussakin (1973) and Fresi et ale
(1980) the Janiridae is the central taxon in the evolutionary
development of all the remaining janiroid families.
This family has
267
been
the
ｾｯｮｳｩ､･ｲ＠
janiroidean
｡ｲｾｨｴｹｰｩｬ＠
many of its
｢･ｾ｡ｵｳ＠
features are those found in other superfamilies, giving it the
of the presumed
｡ｰ･ｲｮｾ＠
of the group.
｡ｮｾ･ｳｴｯｲ＠
a flattened body with broad tergites;
ｓｵｾｨ＠
are
ｾｨ｡ｲｴ･ｳ＠
of an antennal
ｰｲ･ｳｮｾ＠
large biramous uropods; unmodified walking legs; and other
isopodan
These
ｾｨ｡ｲｴ･ｳＮ＠
be found in the genus Santia, in the
ｾ｡ｮ＠
Paramunnidae, and other non-janiroid taxa,
Therefore, they
ｳｵｾｨ＠
as Asellus.
be used to establish relationship.
ｾ｡ｮｯｴ＠
ｴｹｰｩｾ｡ｬ＠
are plesiomorphies at the
ｾｨ｡ｲｴ･ｳ＠
level of the Asellota, and
ｳｾ｡ｬ･［＠
In
addition, the Janiridae have apomorphies at the level of the
superfamily Janiroidea,
the dorsal
ｾｵｴｩｬ･＠
pereopodal
ｾｯｸ｡･［＠
ｳｵｾｨ＠
as tergal lappets (lateral
ｰｲｯｪ･ｾｴｩｮｳ＠
of
anterior or posterior to the dorsally visible
see next
the higher Janiroidea.
ｳ･ｾｴｩｯｮＩＬ＠
Several
that set them off from many of
､ｩｳｴｮｾ＠
ｰｨｹｬ･ｴｩｾ＠
lines,
ｳｵｾｨ＠
as that
leading to the munnids and paramunnids, had diverged from the basal
ｳｴｯｾｫ＠
of the Janiroidea before a
These results
｡ｮｾ･ｳｴｲｬ＠
･ｦｾｴｩｶｬｹ＠
ｲ･ｾｯｧｮｩｺ｡｢ｬ＠
janirid had evolved.
remove the Janiridae as the model for an
morphology of the entire Janiroidea.
268
IMPLICATIONS FOR THE CLASSIFICATION OF THE ASELLOTA
The classification of the Asellota should match the best estimate
of the phylogeny of its taxa.
Asellotan phylogeny, however, will
undoubtedly need refinement as more information is collected on the
Gnathostenetroididae and the Protojaniridae, and on the details of the
female reproductive system in these and other families.
Therefore,
this paper will not attempt a systematic revision on the basis of the
cladogram in figure 4.15, although a formal classification for
Pseudojanira and some of the implications of this study must be
discussed.
Pseudojanira stenetrioides previously has been placed in the
family Janiridae (Barnard, 1925; [ensley, 1977), although it must be
removed from the superfamily Janiroidea based on the evidence
presented here.
To include Pseudojanira would dilute any potential
definition of the Janiroidea that might be proposed.
Alternately, it
cannot be placed in any of the other superfamilies of the Asellota
because of its clear affinities to the Janiroidea.
At this point, a
new superfamily could be proposed for Pseudojanira because of its noncorrespondence to any of the existing taxa.
This trend is already
well established in the literature with the creation of new
superfamilies for presumedly new morphological combinations discovered
(vis. Gnathostenetroidoidea (Amar, 1957); Protojaniridae Fresi et al.,
1980, elevated to superfamily by W!gele, 1983; Protallocoxoidea
Schultz, 1978).
A continuation of this trend could result in
"superfamily inflation," severely diminishing utility of the
superfamily concept in the Asellota.
A series of similar taxa sharing
269
possible apomorphies, such as Stenetrium, Gnathostenetroides, and
Pseudojanira could be placed in separate superfamilies because their
male pleopod morphology differed.
The Asellota, save for the
Janiroidea, vary in their pleopod morphology, leading to the
conclusion that there was considerable evolutionary experimentation in
the methods of sperm transfer and fertilization in the ancestors of
this isopod suborder.
Only in the Janiroidea are the pleopods stable
morphologically throughout many species, genera and families.
Although the pleopods are useful for the classification of the
Asellota, future phylogenetic arrangements or these taxa must be based
on additional characters.
Wlgele (1983, p. 257).
This agrees with the position taken by
Therefore, Pseudojanira is classified here as
suborder Asellota, superfamily incertae sedis (non-Janiroidea), family
Pseudojaniridae, until a careful re-evaluation the "lower asellotes"
is made.
EVOLUTION OF REPRODUCTIVE STRUCTURES
The phylogenetic analysis or the Asellota answers a question
posed earlier about the potential coevolution of the cuticular organ
with male copulatory organ.
Because it is found in all Asellota, the
cuticular organ must predate the stylet form or the male pleopod II
endopod.
On the other hand, the stylet evolved to a hypodermic
needle-like organ diagnostic or Janiroidea, as seen in the
Pleurocopidae and the Munnidae, before the opening of the cuticular
organ became separate from the oviduct.
Because the male and female
systems undergo major changes at difrerent hierarchical levels, they
must have evolved independently of one another.
270
The male copulatory system is highly evolved within the
. Janiroidea,and is its chief defining apomorphy.
This pleopodal
system, however, does not appear suddenly with all its components in
place.
Parts of the system are found in non-janiroidean taxa,
indicating that it evolved gradually w,ith some of the specializations
appearing independent of others.
This is an important point, because
the use of these characters in the phylogenetic analysis depends on
their being independent.
In face of the enormous diversity of the
Janiroidea, one is left wondering whether their highly directed and
stereotyped system for. delivering sperm to the females has been a
major factor in their evolutionary radiation.
271
PHYLOGENETIC ANALYSIS OF THE JANIROIDEA
INTRODUCTION
The previous section found the outgroups for the Janiroidea.
It
showed that the Pseudojaniridae n. fame is the sister group to all the
Janiroidea.
In addition, the "higher Janiroidea" have a sister group
in the families Munnidae and Pleurocopidae.
For this analysis,
both outgroups will be used in order to lend certainty to the
polarities used in the character analySis.
The analyses establish the
evolutionary continuity of all the families, and show that the
"janiroid" condition common to most of the families did not occur in a
single step, but arose gradually.
The primary goal of the
phylogenetic analysis, however, is to discover the sister group of the
families Eurycopidae, Ilyarachnidae, and Munnopsidae.
Therefore, this
analysis is only preliminary in nature and should not be expected to
be completely stable under further scrutiny.
I do believe the results
obtained will remain the same in their broad outlines, regardless of
the exact placement of certain families, such as the Haploniscidae or
the Dendrotiidae.
TAXA USED
The composition of the Janiroidea and of its families has been
somewhat unstable, largely due to poor and incomplete descriptions
common in the literature.
Although no attempt is made to remedy the
myriad problems currently facing the student of this superfamily, some
preliminary re-assignments will be made in order to restrict the
characters included for the families.
272
Table 4.3 shows the taxa used here for analysis.
The
olassifioation used here is that of Bowman and Abele (1983) with the
following oorreotions and emendations.
Following Sivertsen and
Holthuis (1980), ftJaeropsididae ll is more oorreotly spelled
Joeropsididae.
ftAoanthomunnopsidae ll Schultz, 1978, is not a valid
family, being based on a member of the family Munnopsidae (Wilson,
1982).
Beoause reoent publioations have perpetuated the error of
Wilson (1980), it is neoessary to reiterate that the oorreot name for
the taxon defined as the ftPleurogoniidae" in Wilson (1980) is
Paramunnidae Vanh8ffen, 1914, by priority.
Svavarsson (1984)
presented oogent arguments for the elimination of the family
Pseudomesidae,with the division of its two genera between the
Desmosomatidae and the Nannonisoidae.
His ohanges are aooepted here.
Beoause the large soale evolutionary features of the Jan1roidea
are being investigated here, pairs of some families were used as
single taxa.
The olose relationships within the pair Munnidae and
Pleurooopidae (name for old Antiasidae), and the pair Paramunnidae and
Abyssianiridae are discussed in Wilson (1980).
The similarities
between the families Haplomunnidae and Dendrotiidae are detailed in
Wilson ( 1976) •
273
TABLE 4.3.
ａｮ｡ｾｳｩ＠
Taxa (Families or Groups of Families) used for Phylogenetic
of the
ｳｵｰ･ｲ｡ｭｩｾ＠
Janiroidea.
The references cited contain
the reasons why the taxa are grouped in this manner.
See text for
further discussion.
TAXON
REFERENCE
Acanthaspidiidae
MelUiies (1962)
Dendrotiidae and Haplomunnidae
Wilson ( 1976)
De smosomatidae
Hessler (1970)
Haploniscidae
Wolff (1962)
Ischnomesidae
Wolff ( 1962)
Janirellidae
Menzies (1962)
Janiridae (limited composition)
This paper
Joeropsididae
Sivertsen and Holthuis (1980)
Macrostylidae
Wolff ( 1962)
Mictosomatidae and Mesosignidae
This paper and Schultz (1969)
Munnidae and Pleurocopidae
Wilson (1980)
Munnopsoids
Wilson and Thistle (1985)
Nannoniscidae
Siebenaller and Hessler (1981)
Paramunnidae and Abyssianiridae
Wilson (1980)
Pseudojaniridae New Family
This paper
Thambematidae
Wolff (1962)
274
As discussed in Wilson and Thistle (198;), important specialized
characters are shared throughout the families Eurycopidae,
Ilyarachnidae, and Munnopsidae.
These families are of the greatest
interest in this analysis, which was undertaken with the hope of
establishing an appropriate outgroup for them.
In this paper, the
three families are united under an informal name, the munnopsoids,
because if they are formally merged their family name will be
Munnopsidae Sars, 1869.
The Microparasellidae includes highly modified, interstitial
forms.
They are not included in this analysis, because information is
lacking on a number of key features, and because many of the
reductional characters found in this family are likely to be derived
independently from those seen in the taxa used.
The
Echinothambematidae is not included in the analysis because specimens
are few, and the described species are not well known.
A number of key apomorphies are shared between Mesosignum and
Mictosoma.
Because of this only the better known family Mesosignidae
was used in the analysis.
The Mesosignidae, however, may be submerged
into the Mictosomatidae in the future.
The Janiridae presented the greatest difficulties in this study.
Although I do not regard what is presented here as a revision for the
family, some patterns are fairly clear.
The diagnosis of the family
given by Wolff (1962) is made entirely of plesiomorphies at the level
of the Janiroidea.
The single apomorphy that might define this family
is an enlarged accessory seta on the dactyli of the pereopods, giving
275
the three-clawed condition the the walking legs.
The current
composition of this family (Wolff, 1962) includes both 2 and 3 clawed
forms.
For the purposes of this analysis, the Janiridae are limited
to the 3 clawed forms.
An additional apomorphy shared with other
families is the presence of "lappets" or paired lateral projections on
the anterior pereonites.
This character is more difficult to use
because the lappets are reduced or absent in many species.
The genera
included under this definition of the Janiridae are: Carpias
Richardson, 1902 (= Bagatus Nobili, 1906, and Janatus Carvacho, 1983),
Ectias Richardson, 1906, (= Ianiroides Kensley, 1976), Ianiropsis
Sars, 1899,
!!!
Bovallius, 1886, Iollella Richardson, 1905, Jaera
Leach, 1814, Janira Leach, 1814, Janiralata Menzies, 1951 (= Rachura
Richardson, 1908?), Notasellus Pfeffer, 1887 (= Iathrippa Bovallius,
1886? or visa versa?), and Vermectias Sivertsen and Holthuis, 1980.
This limited composition of the Janiridae leaves out some genera:
Janthura Wolff, 1962; Fritzianira De Castro and Lima, 1977;
Austrofilius Hodgson, 1910; and Neojaera Nordenstam, 1933 (= Ianisera
Kensley, 1976).
These genera have distinct apomorphies useful at the
family level, and need to re-examined for proper classification.
This
list also excludes the genera of the Microparasellidae, which were
included into the Janiridae by Wolff (1962).
CHOICE AND SCORING OF CHARACTERS
The families of the Janiroidea are morphologically diverse, often
with no continuity of resemblance from family to family.
As a result
many of the characters that define the families are not particularly
276
useful for determining the relationships among families, because the
characters define only single families.
Such autapomorphies add
nothing to the matrix of among family relationships.
To simplify
the data, and accentuate the effect of characters that may show
among family relationships, the autapomorphies were not included in
the analysis.
For example, the specializations for burrowing that
help define the Macrostylidae, such as fusion of the anterior
pereonites, are found in no other family and therefore tell nothing
about relationships of the Macrostylidae to other groups.
Other
important autapomorpbies omitted from the analysis are the natatory
specializations of the munnopsoid families.
Swimming is also found in
the Desmosomatidae and the Nannoniscidae, but is clearly derived
independently from the munnopsoids: both families lack a well defined
natasome, the swimming setae are constructed differently, and the
swimming modifications are often polymorphic within species.
In order to evaluate interfamilial relationships, an effort was
made to find characters that do not change a great deal within
families or groups of families, but show some change over all the
Janiroidea.
The characters introduced in the next section are not
those used in current taxonomy of the janiroidean families.
In fact,
they may seem insignificant to some who are well versed in the
systematics of the field.
This lack of significance may stem from the
low amount of change in the characters, which is a necessary
requirement for the analysis.
277
Two main character complexes were found useful: the third pleopod
,
and the dactylar claws.
The third pleopod is useful because it lost
its stereotyped opercular function in evolving from the ancestral
state, thereby releasing the form of the exopod to vary.
In the
janiroideans, there is a trend of reductions in the previously
opercular exopod, with a few important novelties such as extra plumose
setae.
The dactylar claws show a variety of reductions and novelties
as well often uniquely marking groups of families.
Other characters,
such as the body form and spines on the midline, are included as well,
because they also help identify groups of families.
The characters
from the previous analysis of the asellotan superfamilies are included
to aid in the definition of the outgroup states.
The use of characters of reduction must be approached with
caution, as will be seen in the results.
They quite clearly appear a
number of times independently, thus introducing apparent
incongruencies into the phylogenetic estimate.
Because reductional
characters are being used, I do not expect most of the characters to
be compatible, that is, to give low homoplasy values.
The analysis
will seek the most parsimonious arrangement of the observed character
states, and if a state is arranged so that it must appear
independently more than once, then the arrangement will be assumed to
be correct if it is the most parsimonious arrangement of all the
characters defining the tree.
Although it is not attempted for this
analysis, multiple derivations of the same character state should be
re-examined to determine whether they are homologous or not.
278
In the final analysis, a conservative weighting scheme is applied
to the characters.
Those that demonstrate the relationships between
the Janiroidea and the outgroup taxa, characters 1-15, are given a
high weight to prevent conflicting reduction characters from affecting
the resulting tree.
The remaining characters are either given a
weight of 1 or 2 depending on whether they are reduction characters,
such as loss of setae, or are unique derivations, such as
modifications of the dactylar claws.
Although there is no
theoretically justifiable use of character weighting (Patterson,
1982), I have used it here for practical reasons: some homologies are
more likely to have been misinterpeted than others and should have a
lesser affect on the analysis.
The scoring of the characters for each taxon used was sometimes
difficult, especially since certain families taken as a whole were
polymorphic for the reduction characters.
For polymorphic characters
in the families, the more plesiomorphic state of a reduction character
was chosen.
If the character being surveyed was unique, however, and
also polymorphic over a taxon taken as a whole, then the state that
occurred in the least modified members of the taxon was chosen for the
taxon as a whole.
The rationale for this procedure is to estimate the
character state in the ancestor of each taxon without having to
perform a phylogenetic analysis of all the genera of the taxon (which
in many cases is currently impossible due to inadequate information in
the literature).
The choice of the plesiomorphic reduction character
state should accomplish this goal, and the choice of a unique
character state over the lack of it should account for any cases where
279
the character state was gained and then lost in the more specialized
members of a group.
CHARACTER ANALYSIS
The following characters are those chosen after examining a broad
range of janiroidean taxa for which there were adequate descriptions,
or with which I had direct experience.
They should be regarded
as a restricted subset of the possible characters to be used to define
the families of the Janiroidea.
The resulting character matrix with
the distribution of the characters discussed below among the taxa, is
shown in table 4.4.
Lateral Projections of the Tergites.--The use in janiroid taxonomy of
the appearance or non-appearance of pereopodal coxae in dorsal view is
based on variation in the shape and size of tergal projections of the
pereonites.
Whether one can see the coxae in dorsal view is sometimes
subjective, often depending on the condition of the specimens and the
experience of the observer.
Determining the presence and shape of the
tergal projections is much more useful and concise, and will be used
here.
The outgroup taxa, Stenetrium and Pseudojanira, have tergal
projections, that is, tergite margins that project laterally beyond
the coxae.
In many of the Janiroidean taxa these are lost, but those
that have them display two distinctive configurations.
single projection on each lateral margin.
The first is a
In many taxa, this
projection is broad and covers the coxae, and in others it can become
280
spine like.
If a spinose projection is present it is always single in
these forms, and is seen in genera that have related genera with broad
lateral projections.
In another group of taxa. that have lateral
projections, the lateral margins of the anterior pereonites 2-4 are
concave, and there are two "lappets" on each side of a tergite.
The
:,i>
paired lappets may be tongue-like or spinose.
In the more advanced
deep-sea families, the lappets are present only as spines but retain
their paired configuration.
The evolutionary polarity of the two types of lateral projections
is not completely certain, although a preliminary assessment may be
made.
Stenetrium is known to have both types, although the paired
lappets are primarily restricted to concave lateral margins.
Pseudojanira and the munnid-pleurocopid group of families have only
single lateral projections.
If the doublet rule (Maddison, et al.,
1984) can be applied here, then one can conclude that paired lappets
within the Janiroidea that are in the sister group of the munnidpleurocopid group are apomorphies, and single tergal projections
are plesiomorphies.
Lack of any tergal projections could be derived
from either condition independently, and therefore is not used.
Body Form.--All the outgroup taxa have moderately broad bodies.
This
broadness is independent of tergal projections, as can be shown b.Y
some species of Stenetrium or Munna that have no projections but have
broad, or at least ovoid bodies.
Many janiroideans have narrow, worm-
like bodies, clearly a derived condition.
Although the use of this
character may introduce some homoplasy into the phylogenetic analysis,
-----------
--------------------
281
this apomorpn, defines whole groups of families.
Spines on the Body Midline.--Deep-sea Isopoda are characteristically
spiny, with sharp projections located on practically any part of the
body.
There are, however, two classes of spines that occur repeatedly
and may be present in the absence of q,ther spines: spines on the
dorsal midline, and spines on the ventral midline.
these two types of spines do not co-occur.
Interestingly
Because such spines
are not seen in the outgroups, both characters are separately
derived apomorphies.
Dactylar Claws (fig. 4.16).--"Claws" on the dactyli of the walking
legs are nothing more than modified setae, mechanically strengthened
to aid the animal in walking.
For this character it is easy to
establish the janiroidean ancestral state.
All the "lower" Asellota,
including the Aselloidea, Stenetrioidea, and the outgroup
Pseudojanira, have two large, similarly sized, distal claws and one
more proximal accessory seta (fig. 4.16A).
The position of the
accessory seta varies, but outside of the Janiroidea, it never
resembles the distal claws.
Within the Janiroidea, the pereopodal
claws undergo important modifications that help distinguish major
groupings of the families.
The Janiridae, as defined here, includes those genera in which the
accessory seta is not lost, but enlarged and often moved distally
so that it functions as a third claw (fig. 4.16C).
synapomorpny of the Janiridae and the Joeropsididae.
This is a
282
The remaining janiroidean families have lost the accessory seta,
and many have the posterior claw reduced and modified to varying
degrees (fig. 4.16D-L).
Simple reduction or losses are difficult to
use because they could have occurred many times.
More useful are
unique specializations of the claws that involve more than simple
reductions.
Therefore, the apomorphic character states "loss of the
accessory seta" and "reduction in length 'alone of the posterior claw"
will be be given low weights in the phylogenetic analyses.
The families Munnopsidae, Ilyarachnidae, and Eurycopidae have an
unusual synapomorphy: the anterior and posterior claws curl around
each other, enclosing the sensillae between them (fig. 4.16F-G).
The
claws are subequal in length, indicating they may not have undergone
the length reduction of the posterior claw seen in most janiroidean
families.
More parsimonious trees result, however, i f this highly
modified claw is interpeted as derived from a reduced claw.
A short posterior claw is flattened (fig. 4.16 H) in many of the
families, and is an apomorphy.
The plesiomorphic state is a posterior
claw that is more or less rounded in cross-section.
A group of families, within the set of families that have
flattened posterior claws, also have fine serrations on the margins of
the posterior claw (fig. 4.16 I,J).
Because similar serrations do not
occur in Pseudojanira, the presence of serrations is an apomorphy.
283
Figure 4.16.
A comparison of the dactylar claws on the second
pereopod of Stenetrium, Pseudo janira, and various Janiroidea.
dactyli seen in medial view, except for G and L.
Stenetriidae.
Ischnomesidae.
A, Stenetrium,
a,
B, Pseudojanira, Pseudojaniridae n. fame
Janiralata, Janiridae.
D, Munna, Munnidae.
F, Munnopsis, Munnopsidae.
Ilyarachnidae, lateral view.
Nannoniscus, Nannoniscidae.
All
E, Ischnomesus,
G, Ilyarachna,
H, Haploniscus, Haploniscidae.
J, Eugerda, Desmosomatidae.
Macrostylis, Macrostylidae, medial and lateral views.
I,
K-L,
1 - anterior
claw, 2 - posterior claw, 3 - accessory seta, 4 - sensillae between
anterior and posterior claws, 5 - cuticular shelf posterior to
posterior claw.
284
8
o
F
ｾｇ＠
I
I
L
2
5
285
The Desmosomatidae have
ｴｨｾ＠
last two apomorphies, and have two
additional dactylar clawapomorphies (fig. 4.16 J).
thin and curled posterior claw.
The first is a
Therefore, it is an extension of the
transformation series involving reductions and modifications of the
posterior claw.
The second is a posterior groove in the anterior claw
in which the sensillae lie.
All poteqtial outgroups have a round
cross section for the anterior claw.
The Ischnomesidae also have a
thin and curled posterior claw on the dactyli, but initial
phylogenetic analyses showed the most parsimonious tree results if it
was derived independently in the two tamilies.
The character state
"thin and curled posterior claw" is there tore assigned to two separate
characters, ,one tor the Desmosomatidae and one for the Ischnomesidae. ,
The Macrostylidae, which are highly specialized for burrowing in
many of their teatures, also have a autapomorphy in the torm
dactylar claws ot the anterior pereopods (tig. 4.16 K,L).
ot the
The
sensillae sit outside of the gap between the anterior and posterior
claws, and are large and robust, with many tat tendrils.
The anterior
claw has the posterior groove seen also in the Desmosomatidae, but the
groove contains the tlattened posterior claw, instead of the
sensillae.
The most unusual feature of the macrostylid dactylus is a
flattened extension ot cuticle posterior to the posterior claw that
extends to the tip ot the anterior claw.
The dactylus has a
strengthened, tripartite construction not seen in any other
janiroidean family or in Pseudojanira, and is a autapomorphy ot the
Macrostylidae.
286
Figure 4.17.
A comparison of third pleopods of various Asellota.
stenetrium, Stenetriidae.
B, Pseudojanira, Pseudojaniridae n. fame
0, Notasellus, Janiridae.
D, Munna, Munnidae.
Janiridae.
F, Amuletta, Eurycopidae.
E, Ianthopsis,
A,
287
c
E
288
Pleopod III (figs. 4.17, 4.18).--The third pleopod has been little
used in the familial
ｴ｡ｸｯｮｾ＠
of the Janiroidea, although its states
(
figure heavily in the phylogenies of the superfamilies of the Asellota
(WAgele, 1983).
In the character anal1sis of the superfamilies, the
presence of an opercular third pleopod in males of Notasellus (fig.
4.17 C) and Jaera was shown to establi...sh the continuity of opercular
third pleopods throughout the Asellota.
Because most janiroideans
have opercula made of the first and second pleopods, the previousl1
opercular third pleopods are released evolutionarily from that
function, and vary throughout the families.
Although most of the characters are reduction characters, and
undoubtedly introduce apparent homoplasy into the phylogenetic
analysis, the third pleopod characters are useful because they vary at
the level of families, and tend to change much less at the level of
genera and species.
The reduction characters receive low weightings
in the final phylogenetic anal1sis to reduce the effects of possible
independent duplication of the same character state in several taxa.
The primary reduction series are in the size of the exopod.
The
plesiomorphic state is a very large exopod that is both longer and
broader than the endopod.
The first transformation series is a decrease in width of the
exopod: the plesiomorphic state "broader than endopod," the
intermediate state "approximately same width as endopod," and the
terminal apomorphy "narrower than endopod."
Once reduced from a
larger state, the exopod is much less likely to become large, thus
289
limiting the possible combinations for this transformation series.
Possible combinations are a "fork" where the exopod goes directly from
the ancestral state to either of the reduced states, or a "straight
line" where the intermediate width exopod is truly intermediate
evolutionarily.
Both combinations were tested in the phylogenetic
analyses and the "straight line topology" produced the trees with the
fewest changes of all the character states.
The second transformation series is in the length of the exopod
compared to that size of the endopod.
The character states are "longer
than endopod," "near same length as endopod," or "distinctly shorter
than endopod."
This series can also be represented by a "fork" or a
"straight line," requiring the testing of both possibilities in the
phylogenetic analysis.
Again the "straight line" produced the most
parsimonious trees.
The fusion of the exopod in many taxa yields a two state
character: "exopod with two segments" or "exopod with only one
segment."
The exopods of Pseudojanira, Munna, and Paramunna have two
segments, so the first state must be a plesiomorphy, and the second
state an apomorphy.
Some of the family level taxa of the Janiroidea vary in the
setation of the third pleopod.
This setation is very conservative in
the "lower" Asellota, making it easy to assess the ancestral state.
The two immediate outgroups of the Janiroidea, Stenetrium and
Pseudojanira, have nearly identical setation on the third pleopods
290
Figure 4.18.
Janiroidea:
A comparison of third pleopods of various higher
A, Janirella, Janirellidae.
B, Dendrotion, Dendrotiidae.
C, Thambema, Thambematidae.
D, Mesosignum, Mesosignidae.
Rapaniscus,. Nannoniscidae.
F, Ischnomesus, Ischnomesidae.
G,
Haploniscus, Haploniscidae.
H, Momedossa, Desmosomatidae.
I,
Macrostylis, Macrostylidae.
E,
291
A
o
292
(fig. 4.17 A-B), although some Stenetrium have extra plumose setae on
the endopod.
ｾ･＠
ancestral state of the Janiroidea should be the same
using the doublet rule of Maddison et ale (1984).
In these two taxa
and in Notasellus, the endopod has three large plumose setae and the
exopod has simple setae only.
Ignoring the shape of the exopod, this
is the configuration of setae seen in.,..many of the Janiroidea.
In some
families, however, are found additional plumose setae, providing
several useful character states.
The first character is whether or not the endopod has more than
3 plumose setae (fig. 4.17 E-F; 4.18 A).
As said above the
plesiomorphic state is "only 3 plumose setae" and the apomorphic state
is "more than 3 plumose setae."
In taxa which have more than 3
plumose setae on the endopod, the exact number can vary considerably
so that, given current information, the apomorphic state cannot be
subdivided accurately.
Such subdivision may be useful for species-
level or genus-level taxa.
The second transformation series contains three possible states:
"no plumose setae on exopod," "one plumose seta on exopod (fig. 4.18
F)," and "more than one plumose seta on exopod (fig. 4.17 E-F)."
ｾ･＠
plesiomorphic state is an absence of plumose setae, and the simplest
description of this transformation is that plumose setae appeared on
the exopods only once, indicating a straight line topology for the
transformation series would be best.
The phylogenetic analyses,
however, showed that the best tree for the Janiroidea resulted from an
independent derivation of the two states, a forked topology.
293
THE RESULTS OF THE CHARACTER ANALYSIS
The following list gives a brief description of each character
state and its polarity based on the above outgroup analYSis, the
weights (Wt
= n)
used in the final phylogenetic analysis, and whether
Wagner (W) or Camin-Sokal (C) parsimony methods were llsed.
The first
'","
15 characters are those from the section analyzing the relationships
among the'superfamilies (see table 4.2).
These first 15 characters
were given a weight of 5 because they were already show to be highly
compatible.
method.
They were analysed using the Camin-Sokal parsimony
The distribution of the character states among the taxa is
shown in table 4.4, and the taxon-character matrix factored to
completely binary states, with the parsimony methods and weights, is
shown in table 4.5.
1.-15. See previous section.
16. Tergal projections,
i f any, single broad plate
(0), or tergal
projections as paired lappets on anterior pereonites (1).
(1 ) •
18.
W)
(Wt
= 1,
C)
No spines on dorsal midline (0), or spines on dorsal midline (1).
(Wt
(W
= 1,
Body at least moderately broad (0), or body narrow or worm-like
17.
19.
(Wt
= 2,
W)
No spines on venter (0), or spines on ventral midline (1).
= 2,
W)
294
20.
(W
Pereopodal dactyli with (0), or without (1) accessory seta.
=
21.
Pereopodal dactyli with simple (0), or claw-like (1) accessory
seta.
22.
(W
23.
2, C)
(W
= 2,
Pereopodal dactyli with large
=
(W
= 2,
C)
Pereopodal dactylar posterior claw rounded (0), or flattened (1)
(W
= 2,
C)
Pereopodal dactylar posterior claw without (0) or with (1)
marginal serrations or teeth.
26. and 34.
two taxa.
= 2,
C).
(This character independently derived in
W = 2, C)
Pereopodal anterior dactylar claw without (0) or with (1)
posterior groove.
28.
(W
Pereopodal dactylar posterior claw not thin and curled
(0) or thin and curled (1).
27.
or small (1) posterior claw.
Pereopodal dactylar claws do not (0), or do enclose (1) the
in cross-section.
25.
(ot,
1, C)
sensillae.
24.
W)
(W
= 2,
C)
Pereopodal dactylus without (0) or with (1) flattened extension
of cuticle posterior to the posterior claw giving claws a strengthened
tripartite form.
(W
= 2,
C)
295
29.
Exopod of pleopod III broader than endopod (0), same width as
endopod (1), or narrower than endopod (2).
This sequence has a linear
derivation with state (1) as the intermediate.
30.
(W = 1, C)
Exopod of pleopod III longer than endopod (0), near same length
as (1), or distinctly shorter than endopod (2).
This sequence has a
linear derivation with state (1) as the intermediate.
31.
= 1,
C)
Exopod of pleopod III 2 segmented (0) or fused into a single
segment (1).
32.
(W
= 1,
C)
Endopod of pleopod III with three plumose setae (0) or more than
three plumose setae (1).
33.
(W
= 2,
W)
Exopod of pleopod III with no (0), one (1), or many (2) plumose
setae.
(W
(W
=
Character states 1 and 2 are independently derived from
2, W)
o.
TABLE 4.4. Character States for the Taxa used in the Phylogenetic Analyses.
Description of the characters in text.
TAXON
1
2 3 4 5 6 1 8 9 10 11 12 13 14 15 16 11 18 19 20 21 22 23 24 25 26 21 28 29 30 31 32 33 34
Pseudojaniridae
0 0 1 0 0 1 1 1 1 1 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Iblnidae
0111011110110110000101000000100000
& Pleurocopidae
Paramunnidae
1 1 1 1 0 1 1 1 1 0 1 1 0 1 1 0 0 1 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0 0
& Abyssianiridae
Acanthaspidiidae
1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 1 0 1 0 1 0 1 0 0 0 0 0 0 1 0 0 1 1 0
Dendrotiidae
& Haplomumidae
Desmosomatidae
1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 0 0 0 0 1 0 1 0 0 0 0 0 0 2 0 0 0 0 0
Haploniscidae
1111011110111210000101010000221000
Ischnomesidae
1 1 1 1 0 1 1 1 1 0 1 1 1
2 1 1 1 1 0 1 0 1 0 1 0 0 ｾｏ＠
lanirellidae
1 1 1 1 0 1 1 1 1 0 1 1 1
2 1 1 0 1 0 1 0 1 0 0 0 0 0 0 2 1 0 1 0 0
laniridae
1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
loeropsididae
1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 0 0 0 0 0 1 0 0 0 0 0 0 0 2 0 0 0 0 0
Macrostylidae
1 1 1 1 0 1 1 1 1 0 1 1 1
1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 0 1 0 1 1 0 1 0 1 1 1 1 0 2 2 1 0 0 0
0 2 1 0 0 2 1
2 1 0 1 0 1 1 0 1 0 1 0 0 1 1 2 1 0 0 0 0
Plictosomatidae
1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 1 0 0 0 1 0 1 0 0 0 0 0 0 2 2 1 0 0 0
& Mesosignidae
Plunnopsoid Families 1 1 1 1 0 1 1 1 1 0 1 1 1 2 1 1 0 1 0 1 0 1 1 0 0 0 0 0 2 0 0 1 1 0
Nannoniscidae
1111011110111210101101011000221000
Thambematidae
1111011110111210100101000000200000
*
TABLE 4.5.
Actual Taxon-Character ｾｴｲｩｸ＠
Character
used in Phylogenetic Analysis. Multistate characters are factored to binary data.
2 3 4 5 6 7 8 9 10 11 12 13 14 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 29 30 30 31 32 33 33 34
Parsimony Method
C C C C C C C C C C C C C C C C W C IJI IJI C IJI C C C C C C C C C C C C IJI IJI W C
lJIeights Used
5 5 5 5 5 5 5 5 5 5 5 5 5 555
Ancestral States
000 0 0 000 0 0 0 0 0 0 0 0 0 000 0 0 0 0 0 0 0 0 0 000 0 0 0 0 0 0
Pseudojanirldae
o
Munnidae
& Pleurocopidae
Paramumidae
&Abyssianiridae
Acanthaspidiidae
o
0
o 0
2 2
222 2 2 2
2
2 2 2 2
000
00000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 000
o
o
o
o
o
o
o
o
o
o
o
0 0 0
o
o
1 0 0
o
o
000 000
o
1 1 0
o
o
o 0 0 000
00001100
o 0 0 0
01000000
000 000 0
0 0 0 0 0
o 0 0 0 0 0 0 0
0 0 0 0 000
Oendrotiidae
& Haplomumidae
Oesmosomatidae
o
o
o
o
010
o 1 0 1
Haploniscidae
o
o
o 0 0 0
o
o
000 0
Ischnomesidae
o
o
o
o
o
o
lanirellidae
o
o
o
o
o
o
laniridae
o
o
o 0 0 0
o
loeropsididae
o
o
o
0 0 0 0
o 000 0 0 0
Macrostylidae
o
o
o
Mictosomatidae
& Mesosignidae
Munnopsoid Families
o
1 0
o
o
Nannoniscidae
o
o
o
o
o
o
000
000 0
Thambematidae
o
o
o
o 0
o
00000 0
000 0 000
1
o 1
o
0 0 0 0 0 1
o
0 0 0
o
0
000
0 0 0 0 0 0 0 0 0 0 0 0 000
o
o
o
000
o
o 0 0 0 0 0
o
o
o
o
0 0 0
o
o
000 0
0
0 0 0 0
o
0 0 0 0 0 0
o
0 0 000
1 000 0
000
o 0
l\J
'-'>
-...J
298
THE PH!LOGENETIC ANALYSIS
Figure 4.19 shows the general form of the most parsimonious trees
after the generation of more than 300 separate trees.
The
multifurcation in the tree represents a location of several different
topologies at the lowest parsimony level, as well as relationships
that cannot be determined with the data available (branch lengths of 0
Cl'·
changes in characters).
The general topology of all trees derived was
very near that shown, and the parsimony values varied only in the
range of 7 steps.
The outgroup taxa, Pseudojaniridae,
Munnidae/Pleurocopidae, and Paramunnidae/Abyssianiridae, were very
stable in their position even without weighting of the characters that
determined their outgrou.p position.
If all the characters were completely compatible, there would be
only a single change. in each character for all the taxa, giving a
minimum parsimony value of 37 steps for the cladogram.
The tree form
shown here has 61 character changes, or 24 more than the minimum.
This yields a fairly high homoplasy value of 65% (24/37).
As
discussed earlier, a highly resolved tree was not expected because
many of the characters were reduction characters that could be derived
many times.
This is especially true in the loss of the dactylar
accessory seta, the reduction in the length of the posterior dactylar
claw, and the reduction in length and width of the pleopods.
Because
of the poor resolution of the tree, it is difficult to assign unique
positions to each character change.
figure 4.19.
Therefore this was not done in
299
--."»-
Figure 4.19.
Preliminary phylogenetic tree for the Janiroidea.
tree is not highly resolved; note the large multifurcation.
The
This tree
suggests that most deep-sea isopods are derived from the same
ancestral group.
The closest ancestral group for the munnopsoids is
the Acanthaspidiidae.
The distal horizontal bars indicate groups of
families analysed as a single taxon.
---ｾＭ
300
PSEUDOJANIRIDAE
MUNNIDAE
LEUROCOPIDAE
PARAMUNN IDAE
ABYSSIANIRIDAE
JAN I RIDAE
JOEROPSIDIDAE
ACANTHASPIDIIDAE
MUNNOPSOID FAMILIES
JANIRELLIDAE
DENDROn IDAE
HAPLOMUNN IDAE
THAMBEMATIDAE
ISCHNOMES IDAE
J--L_.....IL-_.L._.....IL-_ _...ｾ＠
_ _- ' _....--...._ _ ESMOSOMAnDAE
301
The derivation of a character was reinterpeted in one place
because the true ancestral state was uncertain.
The specialized
dactylar claws of the munnopsoids have long but modified posterior
claws.
It was initially assumed that this long modified claw was
derived from a long unmodified claw, a choice that forces the
independent derivation of short claws in the two sister groups, the
'oFd-
Acanthaspidiidae and the Janirellidae.
If the precursor state was the
shortened but otherwise unmodified claws of the munnopsoid sister
groups, then the derivation of the shortened posterior claws can be
moved lower in the cladogram, with an exchange of 3 character changes
for 1 change.
This procedure was not carried out with the many other
homoplasies in the tree because it would result in unreasonable
character changes.
For example, any reductions in the size of the
exopod of the third pleopod are unlikely to be followed by an
expansion to a more primitive larger size because the exopod does not
function as an operculum.
In every single version of the tree, the sister group to the
munnopsoids was the Acanthaspidiidae.
The most important apomorphies
shared by these taxa are the extra plumose setae on the endopod and
exopod of the third pleopod.
Spines on the dorsal midline and the
presence of tergal lappets also help define these two taxa, but the
derivation of these characters is less certain, due to their multiple
derivations on the tree.
These two groups also lack many of the
specializations characteristic of many of the other deep-sea
Janiroidea, such as greatly reduced third pleopodal exopods.
I do not
believe that the munnopsoids and the Acanthaspidiidae are as closely
302
related as, say, the Nannoniscidae and the Desmosomatidae because the
munnopsoids have many autapomorphies not used in this tree, evidence
for great deal of evolutionary time after the separation of the former
two groups.
The Janirellidae are another possible sister group of the
Ｎｾ＠
munnopsoids.
This family, however, is highly modified in characters
that could easily be reductions from the acanthaspidiid condition,
such as the loss of plumose setae from the third pleopodal exopod and
its subsequent reduction.
These characters were not coded using this
interpetation, although it is suggested b,y the association of the
Janirellidae to the clade bearing the Acanthaspidiidae.
These two
families also share a tendency toward spininess, corroborating this
impression.
(General spininess, however, is found in so many of the
deep-sea taxa that it was not useful for the phylogenetic analysis.)
Therefore, the best choice for a sister group of the munnopsoids is
the more generalized Acanthaspidiidae.
In Kussak1n's (1973) phylogeny, sister groups to the munnopsoids
are the Janiridae, or more distantly the Joeropsididae, the
Macrostylidae, or the Pseudomesidae.
At the time of his paper, the
Acanthaspidiidae was submerged in the Janiridae, following the
classification of Wolff (1962).
Therefore, some of Kussakin's (1973)
presumed phylogeny of the Janiroidea may be justified, although it was
never made clear how his tree was derived.
.30.3
The tree derived here contains a single multituraation at the
node leading to the Dendrotiidae/Haplomunnidae, the
Mictosomatidae/Mesosignidae, the Haploniscidae, the Thambematidae, and
the remaining narrow-bodied deep-sea Janiroidea.
Of this latter
group, the Desmosomatidae is associated with the families
Macrostylidae and Nannoniscidae, and these three families are well
ｾＳＮ＠
removed from the ancestral janiroidean, as befit their highly derived
body and pereopodal forms.
The Dendrotiidae/Haplomunnidae are
associated with other deep-sea taxa, and do not appear near the basal
branches of the Janiroidea.
These latter two families are probably
not derived from a pleurocopid or munnid ancestor as had been
previously proposed (see phylogenies of Kussakin, 197.3; Fresi et al.,
1980) •
304
DISCUSSION
The estimated phylogeny of the Janiroidea makes the
Acanthaspidiidae the sister group for the munnopsoid families
Eurycopidae, Ilyarachnidae and Munnopsidae.
Because these groups are
placed in the phylogeny near the position of more plesiomorphic
families such as the Janiridae and
ｴｨｾ＠
Joeropsididae, the munnopsoids
may have been in existence for a relatively long time compared to the
other janiroidean deep-sea families.
(Only relative time can be
determined because the branch lengths of the phylogeny are unknown
from the inference techniques used here.)
This suggestion is
corroborated by the enormous variety of munnopsoid forms that have
radiated into all the major deep-sea environments, as well as back
into shallow water.
The inferred phylogeny also has immediate biogeographic
implications.
One of the theses of Wilson (1980) is that the
MunnidaejPleurocopidae and the ParamunnidaejAbyssianiridae groups are
independently derived and have entered the deep sea independently from
each other.
A similar assertion may be made for the Janiridae, which
has a few deep-sea members but is primarily a shallow-water group.
This is a pattern of the primitive janiroideans having shallow-water
distributions but with some representatives in the deep sea.
The remainder of the Janiroidea may show a different pattern.
Although Kussakin (1983) advocated a deep-sea colonization by most of
the families independently, Hessler and Thistle (1975) and Hessler,
Wilson and Thistle (1979) were able to show that many of the families
305
had a sUbstantial portion of their evolution in the deep sea.
The
known distributions of the Janiroidea (Hessler and Thistle, 1975) and
the preliminary phylogeny (fig. 4.19) indicates that a single
ancestral group may have given rise to all the deep-sea families.
This possible ancestor still had eyes because eyes occur in both the
outgroups (Janiridae or Joeropsididaeland in a few genera of the
deep-sea taxa: Ianthopsis, Acanthaspidiidae; Acanthomunna,
Dendrotiidae.
These two genera have what might be called a
"Gondwanaland" shallow bathyal distribution, with records from
Antarctica, New Zealand, Kerguelen, southern South America and
southern Africa.
This suggests that the ancestor to all the deep-sea
isopods may have arisen before or during the breakup of Gondwanaland,
giving a very approximate time of origin of the deep-sea isopods of in
the Jurassic, around 175 million years ago (van Andel, 1979).
It is
not my intent to develop this hypothesis any further, but this is a
possible answer to a question that has been asked many times: how old
are the deep-sea isopods?
CHAPTER 5
A PROPOSED PHYLOGENY AND CLASSIFICATION OF THE MUNNOPSOID TAXA,
WITH SPECIAL REFERENCE TO THE ILYARACBNOID EURICOPIDAE
INTRODUCTION
At this point, an evaluation of the systematic position of the
ilyarachnoid Eur,ycopidae is possible.
The basis for the unity of the
munnopsoid form has been established, and the taxonomic variety of the
ilyarachnoid eurycopids has been described.
The Ilyarachnidae are
better defined by the removal of a potential sister group, Amuletta,
from that family.
The systematic position of the munnopsoid
janiroideans within the isopod suborder Asellota is now better known,
yielding a possible outgroup for the munnopsoids, the
Acanthaspidiidae.
This chapter finds characters that help establish the
relationships between the munnopsoid taxa.
The characters are then
used to derive an estimate of their phylogeny, with the limitation
that the phylogeny is biased toward interpeting the systematic
position of the ilyarachnoid eurycopids.
Therefore, the conclusions
reached here are not general for the munnopsoids, although their
estimated phylogeny provides hypotheses to be tested in the future.
306
307
TAXA USED
The diversity of the munnopsoid taxa and the limited information
on many of them makes it necessary to restrict the number of taxa used
in the phylogenetic analysis.
Another limitation is that the
computerized algorithms are excessively slowed by data sets with more
than 19-20 taxa.
Four criteria establish the subset of taxa (see
table 5.1) analysed here.
They are ilyarachnoid Eurycopids; they are
members of the subfamily Eurycopinae; they are the least modified
representatives of their group; or they are presumed to be closely
related to the Ilyarachnidae.
All genera have been revised recently,
or were evaluated directly from specimens in the collections.
The eurycopid subfamily Bathyopsurinae, which includes the genera
Bathyopsurus and Paropsurus, are highly modified bathypelagic genera.
This group is possibly derived from a Munneurycope-like ancestor.
They are not included in the analysis because information on these
genera are limited, and because they seem to have little in common
with the ilyarachnoid eurycopids.
The eurycopid subfamily Syneurycopinae contains two genera,
Syneurycope and Bellibos, that subsume a fairly wide range of
morphologies.
The subgenus Bellibos (Bellibos) seems to be the least
modified with respect to the other munnopsoids.
The species
ｾＮ＠
ＨｾＮＩ＠
buzwilsoni Haugsness and Hessler, 1979, is chosen as the synerucyopine
model for the analyses.
308
The Munnopsidae sensu stricto contains a variety of morphologies,
but can be best represented by Paramunnopsis.
This genus is similar
to the eurycopid genus Munneurycope in overall appearance.
The Ilyarachnidae has 5 genera with more or less a common body
plan.
The least modified type-genus Ilyarachna was chosen to
represent this family-level taxon.
Two eurycopid genera, Microprotus and Munnicope, were not
included because they are poorly described and only 1 specimen of the
latter genus was found in the collections, eliminating the possibility
of dissection for some of the characters.
A preliminary inspection of
Munnicope showed that this genus has much in common with Munnopsurus
so its omission from the analysis will not seriously hamper the
results.
METHODS
The techniques for the character and phylogenetic analyses are
primarily those used in chapter 4.
An
initial character analysis was
performed, using those characters that appeared to vary little over
all the munnopsoids.
The primitive state of each character was based
on homologies in the outgroups.
The data sets were subjected to
preliminary phylogenetic analyses, and the effect of different
topologies for the transformation series were tested for the lowest
parsimony values (fewest number of character state changes to derive a
particular tree).
Gamin-Sokal or Wagner parsimony methods were chosen
for each character transition, based on whether or not character state
309
reversals seemed possible.
The characters that introduced a large
number of steps into the trees were re-evaluated in order to determine
whether they were interpeted properly.
For example, Eurycope was originally thought to have a frontal
arch but scoring this genus as having this character state generated
trees with high amounts of homoplasy.
On reinspecting all the taxa
for this character, it was discovered that Notasellus in the family
Janiridae had ridges on the frons homologous to those seen in some
species of Eurycope, and that none of the potential outgroup taxa had
anything resembling the frontal arches seen in Amuletta, Munneurycope,
or Betamorpha.
The decisive observation was that Munneurycope had
ridges on the frons between the antennulae (in the same position as in
Eurycope) above the frontal arch.
Therefore, the frontal arch was
interpeted as a unique apomorphy of some of the munnopsoid taxa, and
Eurycope was scored as lacking this apomorphy.
During this process many characters were rejected as useful at
the systematic level of munnopsoids.
Among these were the forms of
the uropods and the mandibles, the shape of the antennular first
article and the length of the antennula, the presence of an enlarged
pereonite 7, fusion of the ventral natasomites, and the absence of
dorsal or lateral spines.
Most of these are known to vary within
genera, corroborating their lack of usefulness at the familial level.
This process resembles compatibility analysis (Felsenstein, 1982)
because it uses those characters that agree on a particular form of
the phylogeny.
Some homoplasous characters were retained, because
310
they helped resolve some branches, and because they were stable in
most taxa.
The plumose setation of pleopods III and IV was the
primary example of this type of character.
Once reasonable values for a set of characters were obtained, a
conservative weighting was applied to them for the final series of
analyses.
Uniquely derived
｣ｨ｡ｲｴ･ｳｾ＠
such as the frontal arch and
the fusion of the natasomal segments, were given a weight of 2, and
reduction apomorphies, such as the loss of plumose setae, were given a
weight of 1.
The rationale for this is that unique characters are
much less likely to be derived more than once than are reduction
characters.
The problem of weighting is discussed in more detail in
chapter 4.
CHARACTER ANALYSIS OF THE MUNNOPSOID TAXA
The natatory morphology unites all the munnopsoids, but the
included taxa vary enormously in the their overall body plan (fig.
1.5), and in the form of such less well recognized features as the
cephalic frons and the pleopods.
Here an attempt will be made to draw
these morphological data together into an analysis of the
relationships between the munnopsoid taxa.
The outgroup found in the
previous chapter, the Acanthaspidiidae, permits assessing the
polarities of the characters.
In most cases, knowledge of the
character states in this family is sufficient to determine the
polarities within the munnopsoids.
In a few cases, however, a suite
of outgroups, including the Janiridae and the Janirellidae, are used.
311
FUSION OF THE NATASOMAL SEGMENTS
The varied degrees ot tusion ot pereonites 5-7 the segments is
one ot the sources ot the morphological diversity in the munnopsoids.
The tunctional necessity to torm a strenghened cuticular tramework tor
the powerful swimming muscles may be a driving torce in the observed
patterns ot tusion seen in the munnopsoids.
In tact, the segmental
arrangement ot muscles is otten lost b,y the migration ot the internal
muscular attachments into the segments anterior to their pereopodal
origins.
Because fusion ot the natasomal pereonites is a general
trend in all the munnopsoids, only certain special patterns could be
singled out tor the analysis.
The plesiomorphic state is complete tlexibility between
pereonites 5-7 and the pleotelson.
and in Munnicope.
This state is seen in Munnopsurus
The latter' genus is most unusual in that pereonites
5 through 7 are also the same size, and have relatively small
pereopodal musculature.
Fusion ot the natasomal pereonites seems to
tirst appear ventrally with nearly complete obliteration ot the
segmental boundaries.
This is best seen in Eurycope, but occurrs in
most ot the other munnopsoid genera.
Notable exceptions are the
Ilyarachnidae, Amuletta, and Hapsidohedra.
The last genus is
morphologically atypical in that the natasome is strongly tlexed
ventrally, a potential tactor in its retention ot free ventral
natasomites.
The Ilyarachnidae are known to be posterior burrowers,
suggesting that some tlexibility in the wedge-like natasome ot these
taxa is necessary.
Little is known ot Amuletta (see chapter 3), so
312
the function of natasomal flexibility in this genus cannot be guessed.
In Storthyngura, the natasomal pereonites vary from a condition where
the sutures are visible, but not flexible, to a totally fused
condition.
For dorsal fusion of the natasomites, several patterns emerge.
All the ilyarachnoid eurycopids have the tergite of pereonites 6 and 7
fused medially, an important factor in estimating their relationships.
The eurycopids Belonectes, Disconectes, and Tytthocope have pereonites
5 and 6 fused dorsally.
Lastly, complete fusion of all the natasomal
pereonites occurs in Baeonectes, Acanthocope, and the Syneurycopinae.
This last character state does not indicate real shared ancestry
between the last three taxa.
Its inclusion in the phylogenetic
analyses added as many steps as taxa to which it was attributed,
indicating multiple convergences.
The partially fused natasome
characters are compatible with others used in the phylogeny, but they
do not provide information on the transition from the partially fused
to the completely fused natasome.
Therefore the completely fused
state is not used in the analysis.
COMPARATIVE SIZES OF THE NATASOMAL PEREONITES
A great variety in the sizes of pereonites 5 - 7 is seen in the
munnopsoids, with anyone of these 3 segments dominating the natasome,
depending on the taxon.
The primitive state, all equal sized
pereonites, is found in few taxa, such as Munnopsurus and Munnicope.
In Eyrycope and many other genera, pereonite 7 becomes enlarged.
An
extreme is seen in the Munnopsidae sensu stricto where the last
313
pereonite is large and pereonite 5 becomes compressed dorsally along
the body axis to a narrow band.
Unfortunately, the inclusion of this
state into the analyses only worsens the homoplasy level,
｣ｨ｡ｲｾ･＠
possibly indicating multiple derivations.
An alternative hypothesis
is that many of the munnopsoids are derived from an ancestor with an
enlarged pereonite 7, and subsequently the size of the pereonite 7 was
reduced in many of the taxa independently.
This latter hypothesis
would exclude Munnopsurus and Munnicope from the taxon containing most
of the munnopsoids.
A choice between these two hypotheses cannot be
made from the information at hand, so this character state is not used
in the analyses.
One character state of the seventh pereonite that unites the
ilyarachnoid eurycopids is extreme reduction in size.
In two genera,
Lipomera and Mimocopelates, the last pereonite is rudimentary, and in
the other three ilyarachnoid eurycopids, it is only a thin band fused
to the anterior segment.
Tytthocope also has a highly reduced
pereonite 7, although it may have obtained this state independently.
Because the states in these taxa are nevertheless similar, they are
scored the same.
MIDGUT
In all outgroups and most of the munnopsoids, the midgut is
straight, or nearly so.
A bent or coiled gut is a useful synapomorphy
of the subgenera of Lipomera, and is included here as a justification
for using these three subgenera as a single group in the analysis.
Figure 5.1.
Cephalons of an acanthaspidiid and several munnopsoids in
frontal oblique view.
Paramunnopsis.
Coperonus.
A,Acanthaspidia.
D, Munneurycope.
B, Eurycope.
E, Munnopsurus.
C,
F, Ilyarachna.
G,
The left antennulae and left antennae have been removed to
expose the frons of the cephal on , and the mandibular palps on the left
sides are also ommitted.
missing.
The maxillipedal palps of D and Fare
Indications on figures: c - clypeus; f - frontal arch; if -
incipient frontal arch; 1 - labrum; m - mandible; r - rostrum.
315
F
316
CLIPEUS
The clypeus on the cephalic frons displays a variety of
modifications, although all forms may be classified in two states.
The first is a dorsomedially rounded clypeus that slopes upward
posteriorly to its attachment point on the frons of the cephalon.
This type of clypeus is found in the
the munnopsoid taxa (fig. 5.1A-D,F).
and in most of
ｾ｣｡ｮｴｨｳｰｩ､･Ｌ＠
It is the plesiomorphic state.
The second type is a "pushed-in" clypeus where it is dorsomedially
angular, and the medial margin in lateral view slopes downward, often
abruptly, to its insertion into the frons.
This apomorphy is seen in
the ilyarachnoid eurycopids (fig. 5.1G), and in Munnopsurus (fig.
5.1E) and Acanthocope.
Within the first taxon, there are two
substates: a steep slope in lateral view from the anterior vertex of
the clypeus to its frons insertion (Coperonus, Hapsidohedra, and
M1mocopelates), and a gradual, sometimes almost level slope (Lipomera
and Lionectes).
It is not certain which of these two substates is
ancestral.
ROSTRUM
An
anterior projection of the cephalon, the rostrum, is ancestral
in the Janiroidea and is seen in somewhat modified form in the
Acanthaspidiidae (fig. 5.1A).
Most munnopsoids have lost the rostrum,
and have a nearly nonprotruding dorsal vertex of the cephalon.
In
some genera, Munneurycope (fig. 5.1C-G) and Paramunnopsis, even the
vertex is indistinguishable because the dorsal part of the cephalon
slopes smoothly down to the frons.
A rostrum is found in a few
genera: Eurycope (fig. 5.1B), Tytthocope, Disconectes, Belonectes, and
317
Baeonectes (Wilson and Hessler, 1980, 1981; Wilson, 1982), although
its form often deviates considerably from the primitive projection
seen outside the munnopsoids.
In some of these taxa the rostrum
becomes very broad and rounded, and does not project from the frons.
Because a narrow, projecting rostrum and a broad, rounded rostrum are
seen within single genera (Eurycope, Disconectes), the rostrate genera
are scored as having the plesiomorphic state of the rostrum.
FRONTAL AROH
One of the surprises of this work was the realization that some
of the munnopsoids have developed a new structure on the cephalic
frons, the frontal arch.
This structure forms the basis for much of
the variety in the frons seen in the munnopsoids.
Eurycope, and the
other rostrate genera show no evidence of having had a frontal arch.
Eurycope often does have a pair of ridges running vertically from the
clypeus to the rostrum (fig. 5.1B), but these same ridges are seen in
the Janiridae.
An incipient frontal arch is seen on the smoothly
convoluted frons of Paramunnopsis: the region just above the clypeus
is flattened and arc-shaped (fig. 5.10).
and
ｓｴｯｲｨｾ｡Ｌ＠
In Munneurycope (fig. 5.1D)
a fully developed frontal arch is seen, where the
arch is a distinct projection from the ventral part of the frons.
In
addition, these two genera also retain the inverted "V" ridges seen in
Eurycope, demonstrating that the ridges in the latter genus are not a
modified form of the frontal arch.
In other genera, the arch shows a
variety of forms, often being massive in some, such as Munnopsurus
(fig. 5.1E), Acanthocope, and Ilyarachna (fig. 5.1F).
Within the
318
ilyarachnoid eurycopids (fig. 5.1G), the frontal arch is flattened,dorsally angular, and sometimes reduced completely.
The flattened
frons of these genera correlates with their possession of strengthened
anterior margins of the cephalon, which may take over much of the
mandibular support structure provided by the frontal arch.
The
character states described here form a linear transformation series:
no frontal arch, incipient frontal arch, well-developed frontal arch
(in a variety of shapes), to a reduced and flattened frontal arch.
MANDIBLE
At first, the mandible appeared to offer a variety of useful
character states in its various subsections.
Preliminary phylogenetic
analyses showed, however, that more often than not their use
introduced a great deal of homoplasy.
For example, an enlarged,
rounded, and sclerotized molar process seemed useful because most of
the ilyarachnoid eurycopids had this apomorphy.
On the other hand,
this apomorphy is found independently in other genera, such as
Eurycope where the entire range is present from a primitive molar
process to the enlarged rounded form.
Another possibly useful
character state was a reduced molar process, although each taxon that
might have been scored for such a reduction had a unique shape to the
reduced molar process, indicating again it happened independently in
each case.
.319
One apomorpby used in the analysis was the presence of an
enlarged, rounded, heavily sclerotized incisor process.
In the taxa
used in the analysis, this is found only in Ilyarachna.
A similar
incisor is also found in Munnopsis.
the analysis because it is
This genus was not included in
highly modified, and is closely related to
Paramunnopsis, a possessor of a
unmodified incisor process.
ｰｲｩｭｾｶ･Ｌ＠
The second apomorpby used in the analysis was the absence of the
mandibular palp, scored· for Amuletta.
The palp is also missing in the
derived ilyarachnids Aspidarachna and Echinozone, which were not used
in this analysis.
In chapter .3, it was concluded that the ancestral
ilyarachnid had a mandibular palp.
Its absence in both some of the
Ilyarachnidae and Amuletta may indicate a propensity for this loss if
a common ancestry for both is accepted.
AMBULATORY PEREOPODS
Pereopods II through IV can be considered the ambulatory
pereopods, with pereopod I performing a manipulative function, and
pereopods V-VII being used for swimming (or burrowing).
A primitive
condition for the pereopods would be all of them more or less the same
length or perhaps getting incrementally longer from front to rear.
The bases of the pereopods in such a plesiomorphic state would also be
approximately the same length.
Although most munnopsoids are
collected with their fragile ambulatory pereopods broken off, enough
literature records of these pereopods exist to use their lengths in
the analysis.
320
The ambulatory pereopods have two useful apomorphies.
bases III-IV in some taxa are shorter than basis II.
First,
Of these taxa,
bases III-IV are longer than wide in some, and in others they are
stocky and robust, their length approximating their width.
sUbstates are placed in a linear transformation series.
These two
Second, the
entire pereopods III-IV are greatly longer than pereopod II in many
",a.
taxa.
Although these apomorphies are undoubtedly functionally
related, their distribution among the munnopsoids indicates they were
attained independently.
NATATORI PEREOPODS V-VII
The natapods display a variety of morphologies that are easily
classified into a few discrete states.
Because the forms of these
limbs are plesiomorphic wi thin the munnopsoids, but autapomorphic at
the level of the Janiroidea, assigning polarities is done by analogy,
rather than direct homology.
Because pereopods V-VII are
approximately the same size or perhaps increasing in length
posteriorly in the outgroup taxa, the same general scheme is assumed
for the munnopsoids even though the outgroup pereopods have an
ambulatory form, and the munnopsoids have natapods instead.
The lengths of the bases of pereopods V-VII in comparison to the
more anterior bases requires less of the analogy assumption.
In the
outgroup, Acanthaspidiidae, all the bases of the pereopods are near
the same length.
This is also seen in many of the munnopsoids.
In
the. others the bases V-VII are distinctly shorter than the anterior
bases.
Not all the ilyarachnoid eurycopids agree on this character:
321
Coperonus and Mimocopelates have the same shortened bases seen in
Disconectes and Belonectes.
Because character state reversals are
possible in the lengths of the bases, this feature was interpeted in
the phylogenetic analysis using the Wagner parsimony method.
Mimocopelates has an useful autapomorphy that justifies retaining
M. anchibraziliensis in the genus: an elongated merus of pereopod V.
For the same reasons as the previous characters, the Wagner parsimony
method was used.
The pereopodal dactyli show several character states useful
the munnopsoid phylogeny.
ｦｾｲ＠
In the outgroups and many of the genera of
the munnopsoids, the dactyli of pereopods V-VII are fairly large,
although generally shorter than the propodi.
A defining apomorphy of
the Munnopsidae is the complete absence of the dactyli on the nata tory
pereopods.
Three genera of the ilyarachnoid eurycopids show a
different apomorphy: the dactylus of pereopod V is reduced to a tiny
lobe, and the more posterior pereopods have large dactyli.
Two taxa considered here lack pereopods VII: Mimocopelates and
Lipomera.
Mimocopelates is also characterized by a reduced pereopod
VI, indicating a trend toward greater reliance on the fifth pereopod
for swimming.
The less modified species of Lipomera have
subequal pereopods V and VI, although the more derived Paralipomera
species also have a reduced pereopod VI.
Because the subgenera of
Lipomera are considered a single taxon in this analysis, they are
scored as having subequal anterior natapods, with the independent
derivation of the apomorphy, reduced pereopod VI, in both
322
Mimocopelates
｡ｮ､ｾＮ＠
(Paralipomera).
In a majority of the munnopsoids, the last pereopod is near the
same size, both in length and in breadth of the broadened carpi and
propodi, to pereopod VI.
Tytthocope has a defining apomorphy in that
the last pereopod is distinctly
ｳｭ｡ｬｾｲ＠
than the more anterior
natapods, but still functionally natatory.
In some genera, such as
Belonectes and Baeonectes, the last pereopod is 10%-15% shorter than
pereopod VI, but it is just as robust, and the swimming setae are long,
unlike the diminutive last pereopod of Tytthocope.
Therefore, only
Tytthocope is scored as having a reduced but natatory pereopod VII.
An unrelated reduction of the last pereopod is seen in the
ilyarachnoid eurycopids and in the Ilyarachnidae.
They both have
reduced last pereopods in which the paddles have become narrow and
most of the plumose setae are lost.
This derived state resembles a
walking leg, although the presence of plumose setae betrays its
natatory ancestry.
Because this character is incompatible with many
others used in the phylogenetic analysis, it is presumed to have been
derived independently in the Ilyarachnidae and in the ilyarachnoid
eurycopids.
As mentioned above, this latter taxon takes the reduction
one step further in two of the genera: the last pereopod is degenerate
or absent.
323
CLEFT IN THE TIP OF FEMALE PLEOPOD II
A number of munnopsoids, including the ilyarachnoid eurycopids,
have a distinct notch or cleft in the tip of the female opercular
pleopod.
The polarity of this character is uncertain.
In some genera
the notch is large and seems to wrap the pleopod around the preanal
ridge, thus leaving the anus exposed, "just as seen in the Janiridae.
In the Acanthaspidiidae and the Janirellidae, the more immediate
out groups , the anus is covered by an extension of the female pleopod
II, much like the form seen in a number of the munnopsoids, notably
Eurycope and Munnopsurus.
In many munnopsoids, the anus is covered,
but a distinct notch is present indicating the two sides of the cleft
have grown together over the anus.
cleft.
These are scored as having the
In some of the ilyarachnoid eurycopids, however, the cleft is
fused totally giving the condition seen in, say, Munnopsurus, but the
cleft is present in congeners or a closely related genus.
Acanthocope
has a small round female operculum with no evidence of the cleft,
although the anus is completely exposed.
The absence of the cleft in
this genus is regarded as having had a different derivation from that
of other munnopsoids which lack clefts.
These character states are all related to whether the anus is
covered or not.
A preliminary examination of these two states of
the female pleopod form reveals two possible routes that a lineage
could develop a covered anus.
The first was described above: the
fusion of the cleft in pleopod II of the female.
A second route is
the elongation of the distal tip of the pleopod, so that the cleft
becomes convex rather than concave, therby covering the anus.
In some
324
groups, it is impossible to decide whether the first or second route
was followed to develop the covered anus.
In the ilyarachnoid
eurycopids, however, a choice was possible, as discussed in the
previous paragraph.
This problem parallels the use of opercular or
non-opercular pleopods to help define the taxa of the Asellota which
was discussed in the previous chapter.
PLEOPODS III-IV
The setation of pleopod III, particularly the presence of
supernumary plumose setae on the exopod and endopod, is important in
establishing the sister group relationship between the
Acanthaspidiidae and the munnopsoids.
Within the munnopsoids, the
variety in this setation can be applied toward discriminating
relationships.
All of the pleopod setation characters are reduction
characters, and therefore must be weighted less than uniquely derived
apomorphies.
The primitive form of the pleopod III within the munnopsoids is
one which has many plumose setae on both the endopod and the exopod.
In many of the munnopsoid taxa, the endopod has only three plumose
setae, which must be considered an apomorphy within the group but is a
plesiomorphy at the level of the Janiroidea.
An explanation of this
might be that the endopod setation has unexpressed polymorphisms that
mayor may not appear, depending on their genetic and developmental
environment within a species.
If this is the case, the extra plumose
setae are still useful for defining the munnopsoid ancestry, but their
325
loss within the taxon may occur several times in the overall
phylogeny.
The loss of plumose setae on the exopod of pleopod III shows
three states, each of which apparently appears independently.
This
interpetation was arrived at by trying a number of different
transformation series in the phylogenetic analysis, and picking the
one that yielded the fewest steps in the overall tree.
Two or three
plumose setae on the exopod defines the ilyarachnoid eurycopids, but
is also seen in Tytthocope.
A single seta occurs on the exopod of
Baeonectes, and a number of the genera, including Eurycope, have no
plumose setae at all.
The exopod of pleopod IV also has plumose setae in many of the
munnopsoids.
The outgroups have exopods with many plumose setae,
indicating this is the plesiomorphic state.
The presence of only a
single seta on the exopod helps define the ilyarachnoid eurycopids,
but this state is seen in a number of the other taxa.
A few taxa,
Acanthocope, Bellibos, and Paramunnopsis, lack plumose setae on the
exopod.
The most parsimonious trees result from a linear
transformation series: many setae to one seta to none.
THE UROPODS
The munnopsoids show a great variety in the form of the uropods,
and it was originally hoped these could provide some characters for
the analysis.
Unfortunately, the uropodal form is unique in many of
the taxa, and attempts to score general characters were fraught with
many assumptions.
Additionally, when some fairly simply defined
326
characters, such as whether the protopod is broad or tubular, are
added to the analysis, they often add nearly as many steps as taxa
scored with the apomorphic state.
The uropod varies too much at the
level of the munnopsoids to be useful for this analysis.
At the systematic level of the ilyarachnoid eurycopids, the
uropod shows a few trends.
The protopod is least modified in
Coperonus, being large and robust, with a medial projection bearing
unequally bifid setae.
or Amuletta.
This is similar to the form seen in Eurycope
In Mimocopelates, the uropod becomes reduced, but still
retains the protopodal medial projection in one of the species, M.
longipes.
In the three remaining genera, the protopod takes a
different direction, that of lengthening and becoming flattened.
In
Lionectes, the protopod is still fairly small but round and flat.
endopod is flattened somewhat as well.
Its
Hapsidohedra continues this
trend with a large, leaf-like protopod, surprisingly similar to the
uropod of the Ilyarachnidae.
Lipomera has the most unusual uropod.
Although it is superficially similar to that of Hapsidohedra in its
broadest form in subgenera Lipomera and Paralipomera, setal homologies
show that the broad leaf-like structure is made of a fusion of the
flattened endopod and the protopod (see chapter 2 in the remarks after
the description of
ｾＮ＠
(Tetracope) curvintestinata.
327
RESULTS OF THE CHARACTER ANALYSES
The following is a list of characters and their states derived
from the above character analyses that is used for the munnopsoidlevel phylogenetic analysis.
Each character is assigned an ancestral
state based on the form found in the outgroup taxa (0) and a number of
derived states (1, 2, or 3).
parsimony method (C
Following the /character states, the
ｾ＠
= Camin-Sokal;
W = Wagner) and the character
weight (Wt = 1 or 2) used in the final phylogenetic analysis is
indicated parenthetically.
for the weighting rationale.
See the methods section of this chapter
The distribution of the character states
is shown in table 5.1, and the actual data used in the analysis with
factored multistate characters is given in table 5.2.
1.
Natasomites dorsally unfused (0), or only pereonite 5 and
pereonite 6 fused medially (1).
2.
(C, Wt
= 2)
Natasomites unfused dorsally (0), or only pereonite 6 and
pereonite 7 fused medially (1).
(0, Wt
= 2)
3.
Pereonite 7 present (0), or reduced or absent (1).
4.
Midgut straight (0) or midgut with distinct bend or loop (1).
(0, Wt
5.
=
1)
= 2)
Olypeus dorsally rounded (0) or dorsally high and angular (1).
(0, Wt
6.
(0, wt
= 2)
Rostrum present (0) or absent (1). (C, Wt = 2)
328
7.
No frontal arch (0), incipient frontal arch (1), distinct frontal
arch (2), frons flat, arch reduced (3).
8.
(e, Wt = 2)
Mandible: incisor process normal (0) or enlarged and heavy (1).
(e,
Wt
= 2)
(e, Wt = 1)
9.
Mandibular palp present (0) or ab,sent (1).
10.
Ambulatory pereopod bases approximately same length (0), bases
III-IV shorter than basis II (1), or bases III-IV length near
width and much shorter than basis II (2).
(W & e, Wt
= 2)
11. Pereopod III-IV similar in length to pereopod II (0) or much longer (1).
(e, wt = 2)
12. Pereopods V-VII bases: near same length of' anterior bases (0), or
shorter than anterior bases (1).
(W, Wt
13. Pereopod V merus short (0) or long (1).
= 1)
(W, wt
= 2)
14. Pereopod V-VII dactyli long (0), or rudimentary/absent (1), or
only pereopod V· dactylus rudimentary absent (2).
(e, Wt = 2)
15. Pereopod VI near same size as pereopod V (0) or smaller (1).
(e,
Wt
= 1)
16. Pereopod VII near size of' pereopod VI (0), smaller than pereopod
VI but functionally natatory (1), smaller than pereopod VI with
narrow carpi and propodi (2), or rudimentary/absent (3).
(e,
Wt
= 1)
329
17.
Pleopod II of female without (0) or with notch or cleft in distal
tip (1), or cleft fused (2).
18.
(W, wt = 2; C, wt = 1)
Pleopod III: exopod distal tip with many plumose setae (0), 2 or
3 plumose setae (1), 1 plumose seta (2), or none (3). (C, Wt
19.
Pleopod III: endopod distal tip with more than 3 plumose
setae (0), or 3 or less plumose setae (1).
20.
(C, Wt = 1)
Pleopod IV: exopod with many plumose setae (0), 1 plumose seta
(1), or no plumose setae (2).
(C, Wt = 1)
Characters added for analysis of the ilyarachnoid eurycopid
within-group relationships.
21. Uropodal protopod without (0) or with (1) medial projection.
(W, Wt
22.
=
= 2)
Uropodal protopod small (0), reduced (1), or enlarged and
flattened (2).
(C, Wt = 2)
1)
330
Table 5.1. Distribution of character states in selected munnopsoid taxa. See text
for a description of the characters. Characters 21 and 22 were evaluated for only
the ilyarachnoid eurycopid genera and Plunnopsurus. In Parsimony l'Iethod, "C" means
Ｂｾ＠
Camin-Sokal method and
CHARACTERS
means Wagner method.
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21
PARSIPIlNY I'ETHOO
C C C C C C we C CJI£ C W W C C C W C C C
c
Acanthaspidiidae
o
Acanthocope
00001
AlNJletta
00000120
Baeonectes
00001
Bellibos
o
Belonectes
22
W
0 0 0 0 0 0 0 0 0 0 0 000 0 0 0 0 0
o
20000
1700000
o
0 0 0 0 0 0
0 0 0 0
0 0 0 0 0
2 0 011
2
000
0 000 211
000 0 0 1 0 1 2
000 0 0 0 0 0 0 0
0 0 0 0 0 3 1
Betamorpha
o
Coperonus
o a
o
Oisconectes
100
a a a a a a a a
Eurycope
a a a
0
a
Hapsidohedra
o
1 1
a
1
300
Ilyarachna
000
a
0
2
Lionectes
o
1
o
1
3
Lipomera
o
1
1
Pl1mocopelates
o
1
o
Plunneurycope
00000120000
Plunncpsurus
00001
Paral1lJnnopsis
o
Storthyngura
000001200
Tytthocope
101000000000001011
0 0 0 0
000
1
a
0
2000100000
o a a
2000010202
1
a a
a
000
a
?
1
a a a
003
a a a a a
a a a a
311
2
1
02100002
000
0 0 0 0 0 2
a
2 2
1 3 0 0 0 0 000
a
3
1
3 1
1
1
a 0 a 003
1
2 0 0
2
0 1
1 2 0 0 0 0 0 0 0 0 0 0 001
1
0
0 1
a
a
000 0
2
000001000
o
2
a
2
o
2
o
0
331
Table S .2. Character-Taxon data IIIItrill used in phylogenetic analysis. I'W.tistata characters have been
factored to binary states.
2 3 • S 6 7 7 7 8 9 10 10 11 12 13 1. 1. 1S 16 16 16 17 17 18 18 18 19 20 20
CHARACTER
PARSIPDIY flETHDD
C C C C C
II£IGHTS
2 2
AtaSTIR
o
6£antt!OI=ope
ewe c c ewe c w wee c c c ewe c c c c c c
2 2 2 2 2 222 2 2 2
a
0
o 000
o
0 0 0'0 0
Anuletta
o a
o 0
Bteonectes
o
0 0 0'0
o
0 0
0
a a
0 0 0
o a
o
a
0
a
a a
0
a a
0
a
0-0 0 0
o a a
Hapsidohadra
o
llvarasma
o
L10nactes
o
Lipameta
o
l'I1!necapelates
o
I'kmaurvcope
a
0 0
a
000
o
0
0
a
7 0 0
a
0
a
o
0
o
0 0 0 000
0
0 0
a a
0
a
0 0
a
a
0
a
o a
0
a a
000
a
000
o
a
a
0 0
000
a
a a a a a a a a a a a
a
a a
a
000 0 0
0
0
? 000
a
0
a
2
o
0 000 0
a a
a a a a a a a
0 0
a a
000
Eum:ape
a a a a
a a
a a
a a a
0 0
a
a
0 0
a a
o
a
a a
0
0 0
o
0 0
a
0 0
a a
000
a
0
a
000
a
0
a
a
StorthynguFa
a a a a a
a
a
o
0
000
0
a
0
0
a
0
a a
0
a
o
0 0 0.0
o
a
o
0
a
o
0
o a
a
a
a
000
a
a a
a
o
0 0 0
a a a
000
a
0
0
a
0
a a
0 0 0
000
0
a a a a a
0
0 0
a
0 0 0
o
a a
a
o
a a a
a
0 0
a
0 0 0 0
o
0
a a a a a
o
a
a a a a a a a
o
0
a a
0 000 0
o 0 0 0 0 0 0 0 000
0
a a
0
0
a a
o
00000 0 0 0
a
0
a
a
a a
0 000
a a a a a
000 0 7 0 0 0 0 0 0
Paremapsis
Tytthocope
0
a
a a
Oisconectes
0
a a
0 0 0 0 0
o a
Copmnus
0
a a
222
a a a a a a
0
0 0 0
a
0
o
0
a a
a a a a
000 0
o
a a
0
a
0
a
332
RESULTS OF THE PHYLOGENETIC ANALYSIS
THE ESTIMATED PHYLOGENY
Figure 5.2 shows the general form of the most parsimonious trees
that can be inferred from the character states developed above.
It
contains several multifurcations at points where a number of equally
parsimonious topologies resulted.
The'homoplasy level is quite high,
approximately 73% for the characters used or approximately 22
unweighted steps more than the minimum.
As in the phylogenetic
estimate of the Janiroidea, the apomorpbies are not shown on the tree
because there is often no unique position for their derivation.
Appendix 4 gives the output for a number of different trees generated
by the program ITERMIX.
The form of the general tree implies three large taxa, although
the some of the major branching nodes are based on multiply derived
characters.
Eurycope and the genera with which it clusters lack the
derived characters seen in the remainder of the munnopsoid taxa: they
all have character states such as retaining a rostrum and not having a
definable frontal arch
(see table 5.1).
These genera are primarily
defined by character states that appear elsewhere on the tree, such as
the pleopodal setation characters.
The relationships within the
group containing Eurycope may be subject to reinterpetation with
further analysis even though Disconectes, Belonectes, and Tytthocope
may form a natural taxon with a defining apomorpby' (dorsally fused
pereonites 5 and 6).
333
Figure 5.2.
Estimated phylogeny or selected munnopsoid genera.
334
EURYCOPE
BAEONECTES
DISCONECTES
BELONECTES
MUNNEURYCOPE
MUNNOPSURUS
ACANTHOCOPE
MIMOCOPELATES
HAPS IDOHEDRA
LIONECTES
,........._ ..._____ LI POMERA
ｾＺＮＭ
PARAMUNNOPSIS
ILYARACHNA
AMULETIA
BETAMORPHA
STORTHYNGURA
335
In a single case, a taxon may be incorrectly placed.
The sister
group of the ilyarachnoid eurycopids is shown to be Acanthocope.
Nevertheless, evidence from the variety of morphologies within the
poorly defined genus Storthyngura indicates these two genera share a
common ancestry.
A comparison of Storthyngura brachycephala Birstein,
1957, and Acanthocope curti cauda
ｂｩｲｳｾ･ｮＬ＠
1970, shows that taxa
classified as Storthyngura have the enlarged muscular cephalon that is
characteristic of Acanthocope.
Because Storthyngura shares
apomorphies with the Amuletta-Betamorpha complex of genera (characters
10 & 11: short bases III-IV and elongate pereopods III-IV), the
absence of these critical apomorphies in Acanthocope may be due to a
secondary loss.
A weakness in this analysis is that the full range
of character states in many of the genera are not known owing to poor
or incomplete descriptions.
DISCUSSION AND PROPOSALS FOR A REVISED CLASSIFICATION
The estimated phylogeny shows that the taxa in the family
Eurycopidae are not closely associated with one another.
In fact,
taxa such as Storthyngura and Betamorpha have more in common with the
Ilyarachnidae than they do with Eurycope at this phylogenetic level.
Thus the previous classification of the munnopsoids as three separate
families is not reflected in the estimated phylogeny.
Because all
munnopsoids have characters that unite them, I propose that the family
Munnopsidae sensu lato of Sars, 1899, be reestablished, with the
existing family groups demoted to subfamilies, except for the
subfamilies of the Eurycopidae which will retain their current rank.
A new classification for the Munnopsidae is shown in table 5.3.
The
336
defining apomorpbies of the Munnopsidae are: pereonites 5-7 enlarged,
muscular, broadly joined, with their ventral nerve cord ganglia fused
into a single mass (Hult, 1941); pereopods V-VII with many long, tully
plumose setae and their· carpi and propodi broadened and paddle-like;
dactylar claws that enclose the distal sensillae in a hollow between
the anterior and posterior claws; and "the rami of pleopod III with
many distal plumose setae.
!!! versions of
The ilyarachnoid eurycopids remain associated in
the phylogenetic estimate
(see appendix 4).
Therefore, they may be
recognized as a distinct subfamily of the Munnopsidae.
Their defining
apomorphies are: dorsal fusion of pereonites 6 and 7, reduction of
pereonite 7, and loss or reduction of pereopod VII.
I propose the
subfamily name Lipomerinae for this new taxon, derived from the
available family-level name Lipomeridae Tattersall, 1905a.
With the
placement of the Acanthocopinae near Storthyngura (discussed above),
the closest sister group for the Lipomerinae is Munnopsurus.
If the
taxa of the Lipomerinae are analysed using the added uropodal
characters (table 5.1) with Munnopsurus as the outgroup to root the
tree, the subfamily resolves into two sub-subfamilial groups (fig.
5.3).
One group contains Coperonus and Mimocopelates, and the other
shows unresolved relationsbips between the genera Hapsidohedra,
Lipomera, and Lionectes.
337
MUNNOPSURUS
COPERONUS·
MIMOCOPELATES
HAPSIDOHEDRA
LIONECTES
,..._...._ _..._ _-.LIPOMERA
Figure 5.3.
eurycopids).
An
estimated phylogeny of the Lipomerinae (ilyarachnoid
The genus Munnopsurus is included as an outgroup.
338
Table 5.3. A revised classification of the Munnopsoid Asellota and
the Ilyarachnoid Eurycopidae. The sequencing convention for
displaying phylogenetic information in the classification (Wiley,
1981) is not used for the genera; after the type-genus, they are in
alphabetical order.
Crustacea Pennant, 1777
Class Malacostraca Latreille, 1806
Subclass Eumalacostraca Grobben, 1892
Superorder Peracarida Calman, 1904
Order Isopoda Latreille, 1817
Suborder Asellota Latreille, 1803
Superfamily Janiroidea Kussakin, 1967
Family Munnopsidae Sars, 1869
Subfamily Munnopsinae Hansen, 1916 sadis mutabilis
Genera included:
Munnopsis Sars, 1861
Acanthomunnopsis Schultz, 1978
Munnopsoides Tattersall, 1905b
Paramunnopsis Hansen, 1916
Pseudomunnopsis Hansen, 1916
Subfamily Acanthocopinae Wolff, 1962 sedis mutabilis
Genera included:
Acanthocope Beddard, 1885
(? Storthyngura Vanh6ffen, 1914)
Subfamily Bathyopsurinae Wolff, 1962 sedis mutabilis
Genera included:
Bathyopsurus Nordenstam, 1955
Paropsurus Wolff, 1962
Subfamily Eurycopinae Hansen, 1916 sedis mutabilis
Genera included:
Eurycope Sars, 1864
Baeonectes Wilson, 1983
Belonectes Wilson and Hessler, 1981
Disconectes Wilson and Hessler, 1981
Tytthocope Wilson and Hessler, 1981
Subfamily Ilyarachninae Hansen, 1916 sedis mutabilis
Genera included:
Ilyarachna Sars, 1864
Aspidarachna Sars, 1899
Bathybadistes Hessler and Thistle, 1975
Echinozone Sars, 1899
Pseudarachna Sars, 1899
339
Table 5.3, continued. A revised classitication ot the Munnopsoid
Asellota and the Ilyarachnoid Eurycopidae.
Subtamily Lipomerinae Tattersall, 1905a sedis mutabilis
Genera included:
Lipomera Tattersall, 1905a
Goperonus n. gen.
Hapsidohedra n. gen.
Lionectes n. gen.
Mimocopelates n. (en.
Subtamily Syneurycopinae Woltt, 1962 sedis mutabilis
Genera included:
Syneurycope Hansen, 1916
B&1libos Haugsness and Hessler, 1979
Subtamily incertae sedis
Genera included:
Amuletta Wilson and Thistle, 1985
Betamorpha Hessler and Thistle, 1975
Microprotus Richardson, 1909
Munneurycope Stephensen, 1913
Munnopsurus Richardson, 1912
Munnicope Menzies and George, 1972
(1 Stortgyngura Vanh8tten, 1914)
340
The estimated phylogeny of the Munnopsidae sensu
ｾ＠
forces a
reconsideration of the composition of the subfamily Eurycopinae.
Wolff (1962) places the following genera in this subfamily: Eurycope,
Lipomera, Munneurycope, Munnopsurus, and Storthyngura.Lipomera is
here assigned to the Lipomerinae Tattersall, 1905a.
possibly be assigned to the Acanthocopinae.
',.
Storthyngura may
The remaining genera are
each quite distinctive and therefore difficult to place.
A temporary
solution is to place the four genera which cluster with Eurycope in
the Eurycopinae, and assign al1 the remaining genera to subfamily
incertae sedis.
341
CONCLUSIONS
The failure to resolve the relationships of the subfamilies of
the Munnopsidae sensu lato is not surprising in view of the diversity
of the included taxa.
a short period of time.
Such a variety of munnopsids could not arise in
It was shown in chapter 4 that the
Munnopsidae branch off from the otherc""deep-sea isopods wi thin only a
few branching nodes of their origin.
If there is any truth to the
hypothesis proposed in chapter 4, that the deep-sea isopods arose from
a single ancestor in the mid Jurassic, then the Munnopsidae may have
had a long evolutionary history with plenty of time to invade most of
the niches available to epibenthic Crustacea that swim.
Proposing a family as large as the Munnopsidae with its 7+
subfamilies and 30+ genera creates a difficulty for the remainder of
the Janiroidea: the family-level taxa no longer seem coordinate in the
variety of morphologies they subsume.
All the other families have
distinctive characters by which genera can easily be allocated to the
proper family.
Moreover, most of the other families have a manageable
number of genera (although many of the genera, such as Haploniscus and
Ischnomesus would benefit from a revision).
The alternative to my proposed classification would be to make
each of the munnopsid subfamilies a family.
To address the monophyly
of the 7+ families thus created, a new taxonomic level in the
janiroidean hierarchy between superfamily and family would have to be
recognized.
Such a proposal has merits: known monophyletic groups of
families in the Janiroidea (see chapter 4) could be recognized by a
342
sub-superfamily hierarchical level.
Unfortunately, the relationships
between many of the deep-sea isopod families are still poorly known,
so such a classification cannot be attempted at this time.
The goal ot this thesis, to establish the systematic
relationships of the ilyarachnoid
･ｾ｣ｯｰｩ､ｳＬ＠
ｾ＠
has been achieved.
These isopods belong in a monophyletic subfamily called the
Lipomerinae, within the family Munnopsidae.
The sister group of the
Lipomerinae is probably the genus Munnopsurus, although the unresolved
relationships of the munnopsid subfamilies make this less certain.
The resemblance of the Lipomerinae to the Ilyaracbninae is due to
convergent evolution in some of their characters, not to proximate
common ancestry.
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APPENDIX 1
A GLOSSARY OF MORPHOLOGICAL TERMS
This glossary contains definitions of morphological terms used
throughout the text.
The definitions given are specific to the study
of isopod taxonomy, with an emphasis on the asellote superfamily
"-
Janiroidea.
Aesthetasc.
A long, tubular sensory seta having thin cuticle, found
on theantennula.
Aesthetascs may have a chemosensory function,
because males generally have many more than females.
Ambulosome.
The part of the thorax of munnopsoid isopods that bears
the walking legs.
Ambulosomite.
It consists of pereonites 1-4.
A body segment of the ambulosome.
Annulus (plural annuli).
(See fig. 1.4)
(See fig. 1.4)
A distal segment of the either the antenna
or antennula, generally tubular in form.
Antenna (synonym, second antenna).
appendage.
The second, paired, cephalic
It consists of four short, robust, proximal segments, two
long, intermediate segments, and a long series of tapering annuli,
called the flagellum.
The third basal segment bears a smaller,
lateral appendage called the antennular scale that is homologous to
the exopod in other Crustacea.
(See fig. 1.4)
354
Antennula (synonyms first antenna, antennule).
cephalic appendage.
The first paired
In munnopsoids, it consists of a wide flattened
basal segment, two segments of intermediate thickness, and distal
annular segments of varying lengths.
generally bear aesthetascs.
Appendix Masculina.
The most distal segments
(See fig. 1.4)
An alternative name for a stylet-like copulatory
structure on the male pleopod II.
This structure is not homologous to
similarly named structures found in non-Isopod Malacostraca.
Article.
A segment of any limb,· but usually applied to the antennula
or antenna.
Basis (plural Bases).
The second segment of a thoracic limb.
See
pereopod.
Biarticulate.
Bifid.
Consisting of two articles or segments.
A structure with two distal tips, as in unequallY bifid seta.
Biramous.
Having two branches, a typical condition for most primitive
crustacean appendages.
Brooding Female.
the coxae.
An adult female with fully-extended oostegites on
In most deep-sea samples, the developing embryos are lost
during sample processing, so it is generally not possible to tell
whether the female was in fact brooding embryos, or whether she
released the young before sampling and had not molted to a preparatory
stage.
355
A sensory seta that has a distinct articulated pedestal,
and two distal rows of long, extremely thin setules. It may be found
Broom Seta.
on the antennulae or any of the pereopods.
Carpus.
The fifth segment of a thoracic limb.
Cephalic Dorsal Length.
See pereopod.
The length ot the cephalon measured in a
straight line along the dorsal midline from the posterior edge to the
anterior vertex or rostrum, depending on which is present.
Cephalon.
The head, or anteriormost body unit.
(See fig. 2.1)
In isopods, the
cephalon bears the eyes, mouth, antennulae, antennae, and 4 pairs of
mouthparts (mandibles, max1llulae, maxillae, and maxillipeds).
(See
fig. 1.4, 2.1)
Chaetotaxy.
The form, number, and shapes of the setae.
Circumgnathal.
Around the biting or grinding surface, as in
circumgnathal denticles.
Claw, Dactylar.
A modified seta found on the distal segment of the
walking legs that is heavily sclerotized and has a sharp tip.
Cleaning Setae.
The unusual multisetulate setae found on the distal
segment of the mandibular palp that are used to clean the antennae or
antennulae.
Clypeus.
An unpaired dorsal unit of the cephalon bearing the labrum
medially and the mandibular fossae laterally.
with the dorsal condyle of the mandibles.
The fossae articulate
(See fig. 2.1)
356
Condyle.
A heavily sclerotized projection of the mandible's dorsal
surface that articulates with the cepbalon in the clypeal fossa.
(See
fig. 2.1)
CopulatOry Male.
.
A fully adult male in the asellote isopod
superfamily Janiroidea identified by having a sperm tube of the second
Ｎｾ＠
pleopod's stylet that is open at its sharp distal tip.
In some specimens at
this terminal stage, the vas deferens connecting to the penile
papilla is visible through the cuticle.
Q2!!. The first or basal segment of a thoracic appendage. See
pereopod.
Cuspate.
Having a sclerotized surface or margin with one or more
rounded projections.
Cuticular.
Of the cuticle.
Cuticular Combs.
Tiny arc shaped or linear groups of cuticular
spines, most easily seen on the distal parts of the mandibular palp,
but may occur elsewhere on the cephalic appendages.
Cuticular Organ.
The paired female copulatory organ of Asellota,
found either ventrally or on the anterior dorsal margin of
pereonite 5.
Dactylus.
(See fig. 4.4, 4.8)
The seventh or distal segment of a thoracic appendage,
bearing one or more distal claws.
Denticle.
See pereopod.
A short, pointed, tooth-like projection of the cuticle.
357
Denticulate.
Having denticles.
A generally robust seta with either a row of
ｄ･ｮｴｩ｣ｵｬ｡ｾＮ＠
denticles or a group of distal denticles.
Dorsum (plural Dorsa).
Dorsal Orifice.
The dorsal surface of a body segment.·
.""
The distal opening of the sperm tube in the
janiroidean male first pleopod.
Endopod.
The medial or interior ramus of a crustacean al'pendage.
In
the Isopoda, another name for a thoracic appendage (exclusive of the
coxa and basis), although more typically applied to inner ramus of a
pleopod or a uropod.
Epimere.
A lateral fold of a som!te I s integument dorsal to the limbs.
Sometimes called the pleurite or tergal fold.
Epipod.
Laterally directed lobe (exite) of the basal segment (coxa)
of the maxilliped.
Exopod.
The lateral or exterior ramus of a crustacean basis.
In the
Isopoda, applied to the outer ramus of a pleopod or a uropod.
Facies.
An appearanCe or Similarity, as in Ilyarachnoid Facies.
358
A specialized seta on the distal tip of the maxilliped's
ｾＮ＠
endite.
It is made of thin, hyaline cuticle (difficult to see) and is
usually broad with many laterally pointed lobes.
In the munnopsoids,
it appears as two distinct types: a medial, more heavily sclerotized
seta with fewer lobes, generally found on the distomedial corner of
the maxillipedal endite; and a thin lamellar
form placed in a row just
,._....
proximal to the distal edge of the endite.
Flagellum (plural flagella).
The long, tapering distal part of either
the antennula or antenna, generally made of many annuli.
Foliaceous.
Leaf-like.
Foregut (synonym Stomodeum).
The crop-like anterior portion of the
gut that is lined with cuticle and has openings to the lateral
digestive caeca and the posterior midgut.
Fossa.
A ventral trough in the clypeus into which the mandible's
condyle articulates.
Frons.
(See fig. 2.1)
The anterior part of the cephalon bearing the clypeus and
lying between the antennulae and antennae and below the rostrum or
vertex.
(See fig. 2.1)
A thiakening of the cephalic frons that provides a
ｆｲｯｮｴ｡ｬｾＮ＠
strengthened arch between the fossal regions of the clypeus on either
ｳｩ､ｾ＠
of the frons.
Generally associated with enlarged and heavily
sclerotized mandibles.
(See fig. 2.1)
359
Geniculate.
segments.
Gnathal.
Gravid.
Knee-like, or displaying an acute angle between two
As in geniculate segments 2 and 3 of the antennula.
Of the biting or grinding surface on the mandible.
Bearing t"ully formed ova or embryos in the ovary.
This is
the condition of fully mature preparatory
females.
:,..
Habitus.
Appearance of the whole animal.
Hemiplumose.
A modified form of the plumose seta in which setules are
found in a row on only one side.
Hindgut (synonym Proctodeum).
The posterior portion of the gut
connected to the anus and lined with auticle.
Incisor Process.
The distal biting part of the mandible that
typically bears one or more pointed cusps.
On its medial side, it
bears the spine !.2!!.
Indurate.
Instar.
Heavily sclerotized or calcified, and often rough.
A discrete stage in a growth series, delimited by successive
molting.
Interantennular.
Between the antennae.
Ischium (plural Ischia).
See pereopod.
The third segment of a thoracic appendage.
360
Labrum.
An unpaired, flat segment of the cephalon that articulates
with the clypeus, and anteriorly covers the mandibles.
Lacinia Mobilis (or Lacinia).
An enlarged, nearly articulated spine
of the mandible's spine row that is adjacent to the incisor process.
It is found only on the left mandible.
On the right mandible, it is
replaced by a large spine similar in shape to the more posterior
members of the spine row.
Lamella.
A broad flattened appendage.
Locking Folds, Dorsal.
dorsal cuticle.
Paired projections o£ the male first pleopods'
They form a seat for the medial edge of the second
pleopods, allowing both pairs of pleopods to function together as an
operculum, or during mating.
Manca.
One of the first three stages or instars of an isopod's
postmarsupial life cycle, wherein the seventh pereopod is absent or
rudimentary.
In certain neotenic Asellota this condition is retained
in the adult, in which the manca stage cannot be identified b.1 these
criteria.
Mandible.
of isopods.
The third cephalic appendage, and first mouthpart appendage
It generally has a lateral three-articled palp and is
made up of the following functional regions: incisor process, spine
row, molar process, dorsal condyle, and posterior articulation.
361
Marsupium.
embryos.
A ventral pereonal enolosure on females for developing
It is oomposed of oostegites projeoting medially from the
ooxae of the anterior pereopods (Pers. I-VI in the munnopsoids).
Maxilla (plural Maxillae, synonym Seoond Maxilla).
The third paired
j
mouth part and fifth oephalio appendage.
I
oonsists of a basal segment bearing three
setose lobes •
.....
Maxilliped.
oephalon.
In the Janiroidea, it
Paired appendage on the posterior and ventral edge of the
Aotually it is the first thoraoio appendage, but its body
somite is fused into the oephalon, and it is modified for feeding.
It
consists of the following funotional parts: ooxa, basis bearing a
flattened and setose endite, palp with 5 segments (isohium, merus,
oarpus, propodus, daotylus), and epipod attaohed laterally to the
ooxa.
Maxillula (plural Maxillulae, synonyms Maxillu1e, Seoond Maxilla).
The seoond mouth part and fifth oephalio appendage.
In the
Janiroidea, it oonsists of two setose lobes: a large outer lobe armed
with robust, tooth-like setae; and a smaller inner lobe with only
small setae.
Merus (plural Meri).
The fourth segment of a thoraoio appendage. See
pereopod.
Midgut.
The oentral region of the orustaoean gut.
and hind gut, this region laoks cutiole.
Unlike the fore
362
Molar Process.
A medial process of the mandible.
Primitively it has
a broad, distal, triturating surface with circumgnathal denticles, a
posterior row of broad, setulate setae, and sensory pores on the distal
surface.
Natapod.
A natatory pereopod of a munnopsoid janiroidean, the fifth
through seventh pereopods.
Natasome.
(See fig.''"1.4)
The often posteriorly streamlined body section of a
munnopsoid janiroidean consisting of the following body segments:
heavily muscularized pereonites 5-7, and the pleotelson.
(See fig.
1.4)
Natasomite.
Oopore.
A pereonite of the natasome.
(See fig. 1.4)
A paired female opening in the ventral cuticle of pereonite
5, through which the fertilized ova are released via the oviduct into
the marsupium.
Oostegites.
Lamellar lobes of cuticle extending medially from the
coxa of an adult female isopod.
They may be seen in two forms:
developing oostegites are small fat lobes that do not cross the
ventral midline; oostegites of the brooding female are broad, long
lamellae that overlap on the ventral midline, fOrming a marsupium for
the developing embryos.
363
Operculum (Female Pleopod(s) II).
A plate over the branchial chamber
of the abdomen of female Janiroideans, consisting of the fused second
pleopods.
The first pleopods are absent in female Janiroidean
Isopods.
Oviduct.
An often complex female organ connecting the ovaries to the
oopores.
In the Asellota, it consists of the following functional
subsections: outer tissues surrounding internal parts; spermatheca,
which mayor may not be covered with cuticle; and cuticular organ, an
often complex cuticular tube.
Ovigerous.
Bearing developing embryos in the marsupium.
(See also
gravid) •
Palp.
A lateral appendage of the mandible or the maxilliped.
Paragnaths (synonyms Paragnathae or Lower Lips).
A pair of ventral
projections of the cephalic cuticle just posterior and medial to the
mandibles.
It consists of two pairs of lobes, a broad lamellar outer
pair with hair-like setae on their inner margins and a thick inner
pair covered with many hair-like setae.
Paucisetose.
Pedestal Seta.
Having few setae.
A spine-like seta that is raised above the dorsal
surface of the body by a pedestal-like outpocketing of the cuticle.
364
Penile Papillae (or Penes).
Male cuticular projections on the
posterior and medial margin of the seventh pereonite.
They contain
the openings of the vasa deferentia.
Pereon.
Thoracic segments 2-8 bearing the locomotory appendages, or
pereopods.
(Thoracic segment 1 is part of the cephalon and bears the
maxilliped).
Pereonite.
Pereopod.
(See fig. 1.4)
A segment of the pereon.
(See fig. 1.4)
One of the seven pereonal appendages.
Consists of the
following segments: coxa, basis, ischium, merus, carpus, propodus,
dactylus.
The coxa of adult female bears oostegites.
The distal five
podomeres are homologous with the endopod of the more primitive
biramous thoracic limb of other Crustacea.
Pleotelson (synonym Pleon).
(See fig. 1.4)
The abdominal part of the body,
consisting of a short segment (pleonite 1) and a long and broad
segment.
The large segment is made of the fused more posterior
pleonites and a terminal segment bearing the anus, the telson.
Primitively, there are six pleonites, the anterior five of which bear
ventral pleopods, and the sixth bearing the uropods.
In the
Janiroidea, only the first pleonite is expressed as a free segment.
(See fig. 1.4)
Pleonite.
A segment of the pleotelson.
(See fig. 1.4)
365
Pleopod.
One of the first five paired, biramous, ventral limbs of the
pleotelson.
In unmodified form, it consists of a basal segment, the
protopod, and two distal rami, the endopod and the exopod.
may be biarticulate.
The rami
Female Asellota lack the first pleopods.
In
male Asellota, the first pleopods are present only as a uniramous
structures (fused into a single elongate plate in the superfamily
Janiroidea).
The rami of the male second pleopod are modified as
copulatory structures.
Pleopods III-V have very thin cuticle and
function as gills (branchiae).
Pleopodal Cavity.
The deeply concave ventral surface of the
pleotelson that encloses the pleopods dorsally and laterally.
Because
the more posterior pleopods function as gills it is sometimes called
the branchial cavity.
Plumose seta.
A feather-like seta that has two dense rows of thin,
long setules beginning at the base of the seta and continuing to the
tip.
Podomere.
A segment of a crustacean appendage.
Preanal Ridge.
A raised transverse ridge on the ventral surface of
the pleotelson situated between the pleopodal (or branchial) cavity
and the anus.
In some munnopsoids, this ridge becomes very large.
Preparatory Female.
Protopod.
An adult female that has developing oostegites.
The basal segment of the pleopods and the uropods.
consists of the fused coxa and basis of the crustacean limb.
It
366
Propodus.
The sixth segment of a thoracic appendage.
Quadrangular.
See pereopod.
Having a truncate distal margin at approximately right
angles to the lateral sides.
Ramus (plural!!!!!).
A branch of an appendage.
Receptaculi (synonym Coupling Hooks).
Modified setae on the medial
margin of the maxilliped's basal endite that have bulbous recurved and
denticulate tips.
They couple with their paired counterparts so that
both maxillipeds can act as a single unit.
Recurved.
. Rostrum.
Curved back on itself •
A projection of the cephalic frons that may also include the
dorsal surface of the cephalon.
Sclerotized.
Sensilla.
With thick and sometimes calcified cuticle.
A modified seta found on the dactylus of the pereopods.
It
is similar to an aesthetasc, but has a heavier cuticle that is covered
with many tiny lobes (often only visible in a scanning electron
micrograph) •
Sensory Pore, Mandibular Molar.
A small pit in the distal surface of
the mandible's molar process that can be seen to connect internally to
a nerve process.
Serrate.
Having a row of short tooth-like denticles.
367
ｾ＠
(plural Setae).
A cuticular process that is clearly articulated
with the basal cuticle.
This structure comes in many forms.
There is
a unfortunate tendency in the literature for some authors to call
heavily sclerotized setae "spines", even though they have smaller
counterparts of the same form named nsetae n by the same authors.
"Spinose seta n or nspine-like seta n
Setulate Seta.
ｩｾ＠
more accurate.
A seta with one or more rows of setules.
It is
different from plumose or hemiplumose setae in that the row is
limited to a section of the shaft, and does not extend from base to
tip.
Setule.
A spine on a seta.
Sperm Tube.
A structure found only in male janiroidean Asellota.
1.
A cuticular tube in the stylet (distal segment of the endopod) of the
male second pleopod, consisting of a ventral opening to a rounded
chamber in the center of the stylet and a confluent tube to the tip of
the stylet.
2.
A cuticular tube formed by the medial fusion of the
male first pleopods, consisting of a funnel-like proximal opening
often covering the penile papillae and a confluent tube to a dorsal
orifice roughly one quarter the length of the pleopods from their
tips.
During copulation, both tubes may form a single channel from
the penile papillae to the female's cuticular organ.
Spermatheca.
A sperm reservoir inside the female oviduct with an
opening to the cuticular organ.
368
Spine.
A pointed outpocketing of the cuticle that is confluent with
the cuticle at its base (not articulated).
Spine Row, Mandibular.
A row of spines on the medial side of the
mandible's incisor process.
The lacinia mobilis on the left mandible
is actually an enlarged member of the spine row.
Sternite.
The ventral surface of a thoracic body segment.
Subchelate.
Having the functional ability to grasp by folding
together two adjacent podomeres of a limb.
Support Ridge, Posterior, Mandibular.
A cuticular ridge on the body
of the mandible that is a continuation of the dorsal condyle, but does
not articulate with the fossa in the clypeus.
Supraclypeal.
Above the clypeus.
Sympod (synonym Protopod).
(See fig. 2.1)
A appendage segment made of the fused
basis and coxa •
. Telson.
anus.
The terminal segment of a crustacean's body, bearing the
In most isopods, the telson is fused to the anterior pleonite.
Tergite.
The dorsal surface of a body segment.
Thoracic.
Tridentate.
Of post-cephalic- segments 1 through 8.
With three denticles.
369
Triturating Surface.
The truncate distal surface of the mandible's
molar process that opposes the same surface on its counterpart.
UnequallY
A seta that is often spine-like and has a
ｂｩｦ､ｾＮ＠
smaller thin seta or hair just proximal to its tip.
The hair can be
seen to have a nerve extending into the cuticle and is probably the
external expression of a sensory nerve•
. Unguis (synonym
Uniarticulate.
Uniramous.
Uropod.
ｾＩＮ＠
A modified seta on the tip of the dactylus.
With only a Single segment.
With only a single branch.
The terminal appendage of the body, belonging to the sixth
pleon1te.
It consists of a basal segment, the protopod, and
primitively two uniarticulate rami, a larger endopod and a smaller
exopod.
(See fig. 1.4)
Venter.
The ventral side of the body.
Vertex.
The anterior and medial margin of the cephalic dorsal
surface.
Y!!
(See fig. 2.1)
Deferens.
Male duct from the testis to the penile papilla for the
passage of sperm.
Whip.!.!!!!.
Similar to the unequally bifid seta, except that it is
generally more slender, and the sensory hair is on the distal tip and
is long and curved.
APPENDIX 2
APPENDIX 2A: Phylogenetic analyses of the Asellota
Output of several runs of the program ITERMIX, which is derived from
the program MIX written by J. Felsenstein, Uni versity of Washington
Mixed parsimon, algorithm, version 2.5}
8 species, 16 characters
Wagner parsimon, method
Ancestral states:
11001 01010
Character-state data:
Munn-Pleur 01110 11110
Gnathosten 11101 00000
Higher Jan 11110 11110
Stenetrioi 00100 01000
Aselloidea 00000 00000
Para-Abyss 11110 11110
Protojanir 11101 00010
Pseudojani 00100 11111
00000 0
11010
01000
11111
01000
00000
11010
01000
01000
1
0
1
1
0
1
0
1
Aselloidea
! Higher Jan
t t
! *-Para-Abyss
! !
! *---Munn-Pleur
! !
! ＪｾＭｐｳ･ｵ､ｯｪ｡ｮｩ＠
! !
! *---------Stenetrioi
1 !
1 !
Proto j anir
! !
1
/
*-*-------------*--Gnathosten
requires a total of
17.000
steps in each character:
0123456789
ＪＭｾ
01
101
1
1
1
1
1
1
1
1
1
1
1
1
1
370
1
1
2
371
Mixed parsimony algorithm, version 2.51
8 species,
16 characters
Wagner parsimony method
Ancestral states:
??OO? O?O?O 00000 0
Character-state data:
Protojanir
Stenetrioi
Aselloidea
Pseudojani
Gnathosten
Munn-Pleur
Higher Jan
Para-Abyss
I
??101
00100
00000
00100
??101
01110
11110
11110
00010
01000
00000
11111
00000
11110
11110
11110
01000
01000
00000
01000
01000
11010
11111
11010
0
1
0
1
0
1
1
1
Aselloidea
1
1 Gnathosten
1 1
1 *-Protojanir
1 1
1 1
Stenetrioi
1
1 1
1 1
1 Pseudojani
1 !
1 1
! ! Higher Jan
! !
! ! !
! !
! !
! ! *-Para-Abyss
! !
! ! !
*--*-----*--*--*-----Munn-Pleur
requires a total or
17.000
steps in each character:
0
1 2 3 4
5
6
7
8
1
1
1
1
1
1
9
*-----------------------------------------
O!
101
1
1
1
1
1
1
1
1
1
best guesses or ancestral states:
o1 2 3 4 5 6 7 8 9
*--------------------
01
0 0 0 0 0 0 0 0 0
101 0 0 0 0 0 0 0
2
372
Mixed parsimony algorithm, version 2.51
8 speoies,
16 oharaoters
Wagner parsimony method
Anoestral states:
11001 01010 00000 0
Cbaraoter-state data:
Para-Abyss
Protojanir
Pseudojani
Munn-Pleur
Stenetrioi
Higher Jan
Gnathosten
Aselloidea
11110
11101
00100
01110
00100
11110
11101
00000
11110
00010
11111
11110
01000
11110
00000
00000
11010
01000
01000
11010
01000
11111
01000
00000
1
0
1
1
1
1
0
0
Aselloidea
!
!
!
!
!
!
Gnathosten
!
*-Protojanir
!
Stenetrioi
1
! Pseudojani
1 1
! !
! ! Para-Abyss
! !
1 ! !
1 !
1 1 *--Higher Jan
1 ! !
1 1
*--*----*--*--*----Munn-Pleur
1
1 1
! 1
1 !
/
requires a total ot
17.000
steps in each oharaoter:
0 1 2 3 4
ＪＭｾ
01
101
1
1
1
1
1
1
1
1
1
5
6
7
8
9
1
1
1
1
1
1
2
best guesses ot anoestral states:
o1
2 3 4 5 6 7 8 9
*--------------------
01
0 0 0 0 0 0 0 0 0
101 0 0 0 0 0 0 0
373
Mixed parsimony algorithm, version 2.51
8 species,
16 characters
Wagner parsimony method
Ancestral states:
11001 01010 00000 0
Character-state data:
Munn-Pleur
Higher Jan
Protojanir
Pseudojani
Gnathosten
Stenetrioi
Para-Abyss
Aselloidea
01110
11110
11101
00100
11101
00100
11110
00000
11110
11110
00010
11111
00000
01000
11110
00000
11010
11111
01000
01000
01000
01000
11010
00000
1
1
0
1
0
1
1
0
Aselloidea
1
1 Munn-Pleur
1 1
I 1 Para-Abyss
1 1 1
1 *--*--Higher Jan
1 1
1 *--------Pseudojani
1 1
1 *-----------Stenetrioi
1 1
Gnathosten
1 !
1 1
1
*--*--------------*--Protojanir
/
requires a total of
17.000
steps in each character:
o 1 2 3 4
5
6
7
8
9
*----------------------------------------1 1 1
1 1 1 1 1 2
01
101
1
1
1
1
1
1
best guesses of ancestral states:
o1 2 3 4 5 6 7 8 9
*--------------------
01
0 0 0 0 0 0 0 0 0
101 0 0 0 0 0 0 0
1
374
Mixed parsimony algorithm, version 2.51
8 species,
16 characters
Wagner parsimony method
Ancestral states:
??oo? O?O?O 00000 0
Character-state data:
Munn-Pleur
Protojanir
Aselloidea
Stenetrioi
Higher Jan
Para-Abyss
Pseudojani
Gnathosten
01110
?1101
00000
00100
11110
1111 0
00100
??101
11110
00010
00000
01000
11110
1111 0
11111
00000
11010
01000
00000
01000
11111
11 01 0
01000
01000
1
0
0
1
1
1
1
0
Aselloidea
I
I Pseudojani
1 I
1 1 Higher Jan
1 1 1
1 1 *-Para-Abyss
1 1 1
I *--*-----Munn-Pleur
1 1
1 *----------Stenetrioi
1 1
Protojanir
1 1
1 1
I
/
*-*-
·---------*--Gnathosten
requires a total ot
17.000
steps in each character:
0123456789
*----------------------------------------1 1 1 1 1 1 1 1 2
01
101
1
1
1
1
1
1
best guesses ot ancestral states:
o1 2 3 4 5 6 7 8 9
*--------------------
01
0 0 0 0 0 0 0 0 0
101 0 0 0 0 0 0 0
1
375
APPENDIX 2B.
Phylogenetic Analysis of the Janiroidea
Output of several most parsimonious trees from ITERMIX.
Because the
characters are weighted, the parsimony values are multiplied by the
weights for each characters.
being used:
Note that mixed parsimony methods are
W - Wagner method, S - Camin/Sokal method.
Mixed parsimony algorithm, version 2.51
16 species,
30
characters
Parsimony methods:
SSSSS SSSWS WWSWS SSSSS SSSSS SWWWS
Characters are weighted as follows:
o
1
2
3
4
5
6
7
8
9
*------------------------5 5 5 5 5 5 5 5 1
O!
10!
20!
30!
1 2
2 2
2
2 1 2 1 2 2 2 2
1 1 1 1 1 2 2 2
Ancestral states:
00000 00000 00000 00000 00000 00000
Character-state data:
Nannonisc
Pseudojan
Janirellid
Ischnomes
Dend/Haplo
Para/Abyss
Desmosomat
Thambemat
Janiridae
Haplonisc
Joeropsid
Munn/Pleur
Macrostyl
Acanthasp
Mesosignid
Munnopsoid
11110
00011
11110
11110
11110
11110
11110
11110
11110
11110
11110
01110
11110
11110
11110
11110
11101
00000
11110
11111
11100
01000
11101
11101
11110
11100
11100
01000
11101
11110
11110
11110
01101
00000
10101
10101
00101
10101
01101
00101
00010
00101
00010
00101
01101
10101
00101
10101
01100
00000
00000
01000
00000
00000
01111
00000
00000
01000
00000
00000
01001
00000
00000
10000
01111
00000
01110
01110
01100
01000
01111
01100
00000
01111
01100
01000
11110
01000
01111
01100
10000
00000
11000
10011
00000
00000
10000
00000
00000
10000
00000
00000
00000
01100
10000
01100
376
Munn/Pleur
!
!
!
!
!
1
!
!
!
!
1
!
I
I
I
!
1
I
I
I
t
t
I
I
I
I
!
Para/Abyss
!
! Mesosignid
! !
! 1 Haplonisc
! t !
! I I Is chnomes
1 I 1 I
I 1 ! 1 Nannonisc
1 II! 1
1 1 1 I *--Desmosomat
! 1 1 1 I
I *--*--*--*-----Macrostyl
1 1
I !
Dend/Haplo
1 1
I
1 *-----------------*--Thambemat
I I
Acanthasp
1 1
!
1 !
1 I
*--Munnopsoid
!
1 1
! *-----------------------*-----Janirellid
! !
1 1
Janiridae
1 !
!
*--*--*--------------------------------*--Joeropsid
!
/
/
*--------------------------------------------Pseudojan
requires a total or
102.000
weighted steps in each character:
0
1
2
3
4 5 6
ＪＭｾ
01
101
201
301
7
8
5
6
5
5
5
5
5
5
5
2
2
3
2
4
4
3
3
2
4
2
2
2
2
2
2
2
5
9
4
2
2
377
Mixed parsimony algorithm, version 2.51
16 species,
30
characters
Parsimony methods:
SSSSS SSSWS WWSWS SSSSS SSSSS SWWWS
Characters are weighted as follows:
0 1 2 3 4 5 6 7 8 9
*--------------------------------1
O!
101
20!
301
5 5 5 5 5 5 5 5
1 2 2 1 2 1 2 2 2 2
2 2 1 1 1 1 1 2 2 2
2
Ancestral states:
00000 00000 00000 00000 00000 00000
Character-state data:
Haplonisc
Macrostyl
Thambemat
Janiridae
Para/Abyss
Munn/Pleur
Mesosignid
Desmosomat
Dend/Haplo
Joeropsid
Nannonisc
Acanthasp
Pseudojan
Janirellid
Munnopsoid
Is chnomes
11110
11110
11110
11110
11110
01110
11110
11110
11110
11110
11110
11110
00011
11110
11110
11110
11100
11101
11101
11110
01000
01000
11110
11101
11100
11100
11101
11110
00000
11110
11110
11111
00101
01101
00101
00010
10101
00101
00101
01101
00101
00010
01101
10101
00000
10101
10101
10101
01000
01001
00000
00000
00000
00000
00000
01111
00000
00000
01100
00000
00000
00000
10000
01000
01111
11110
01100
00000
01000
01000
01111
01111
01100
01100
01111
01000
00000
01110
01100
01110
10000
00000
00000
00000
00000
00000
10000
10000
00000
00000
10000
01100
00000
11000
01100
10011
.378
Pseudojan
/
I
ＪＭｾｄ･ｮ､Ｏｈ｡ｰｬｯ＠
!
1 Munn/Pleur
I 1
! ! Para/Abyss
1 1 !
I ! 1 Joeropsid
1 1 1 !
! ! ! *--Janiridae
! ! ! 1
I 1 t 1
Munnopsoid
1 ! ! !
I
1 I I !
*-Acanthasp
1 I 1 1
!
1 ! ! !
*--Janirellld
! 1 ! !
!
Thambemat
I I ! I
1
! 1 ! 1
!
!
! 1 I !
I
1 De smosomat
!
! ! 1 !
! !
I I 1 1
1
1 *--Nannonisc
! 1 ! 1
! 1
1
! 1 ! 1
!
! *--Macrostyl
I I 1 I
! I
I
1 I ! !
Haplonisc
!
! !
!
! 1
! 1 ! !
!
!
! *--------*--Ischnomes
! ! 1 1
! ! ! 1
!
! !
!
! ! ! 1
*--*--------------Mesosignid
I ! ! !
!
!
requires a total or
102.000
weighted steps in each character:
1
2
0
.3
4 5 6
ＪＭｾ
01
5 5 5 5 5 5
101
6 2 .3 2 .3 2
.3
201
4 2 4 4 2 .3 4
.301
2
7
5
2
2
8
5
2
2
9
4
2
2
379
Mixed parsimony algorithm, version 2.51
16 species,
30
characters
Parsimony methods:
SSSSS SSSWS WWSWS SSSSS SSSSS SWWWS
Characters are weighted as follows:
o 1 2 3 4 5 6 7 8 9
ＪＭｾ＠
O!
10!
20!
5 555 5 5 5 5 1
12212 1 2 2 2 2
2 2 1 1 1 1 1 2 2 2
301
2
Ancestral states:
00000 00000 00000 00000 00000 00000
Character-state data:
Mesosignid
Nannonisc
Haplonisc
Macrostyl
Ischnomes
Pseudojan
Para/Abyss
Acanthasp
Thambemat
Janirellid
Desmosomat
Munnopsoid
Munn/Pleur
Dend/Haplo
Janiridae
Joeropsid
11110
11110
11110
11110
11110
00011
11110
11110
11110
11110
11110
11110
01110
11110
11110
11110
11110
11101
11100
11101
11111
00000
01000
11110
11101
11110
11101
11110
01000
11100
11110
11100
00101
01101
00101
01101
101 01
00000
10101
10101
001 01
10101
01101
10101
00101
00101
00010
00010
00000
01100
01000
01001
01 000
00000
00000
00000
00000
00000
01111
10000
00000
00000
00000
00000
01111
01111
01111
11110
01110
00000
01000
01000
01100
01110
01111
01100
01000
01100
00000
01100
10000
10000
10000
00000
10011
00000
00000
01100
00000
11000
10000
01100
00000
00000
00000
00000
380
Pseudojan
1
I Munn/Pleur
r I
1 1 Para/Abyss
I I !
I I ! Janiridae
! ! I J
I I ! *--Joeropsid
! ! I I
t I I I
Thambemat
I 1 I I
I
1 Is chnomes
! I I!
I ! ! I
! I
I ! I I
I *--Haplonisc
! I I I
L I
I I I I
I" I
Desmosout
I! II
II
1
*-Nannonisc
I 1 I 1
1 I
1I11
II
I
I I I I
1 *---*----Macrostyl
I I I I
1 1
I I I I
*--*-------------Mesosignid
I 1 I I
I
1 1 1 I
*--------------------Dend/Haplo
I I I I
I
Acantbasp
I 1 II!
I I I I
!
I
*--Munnopsoid
I I I I
I
I I 1 I
1
I
/
/
*--*--*--*-----*----------------------*----Janirellid
requires a total of
102.000
weighted steps in each character:
ＪＭｾ
01
101
201
301
0123456789
555
362 3
4 2 4 4
2
5
2
2
5
3
3
5
2
4
5
2
2
5
4
2
2
2
2
381
APPENDIX 2C:
An example of how the program MIX analyses the trees by
finding the most parsimonious tree for the first three taxa, and then
adding the next group in the list to the tree in the most parsimonious
plaoe sequentially.
The data were randomized with the ITERMIX program
module.
Mixed parsimoll1' algorithm, version ＲＮｾＵＱ＠
8 speoies,
16 oharaoters
Wagner parsimoll1' method
Anoestral states:
??OO? 01010 00000 0
Charaoter-state data:
Munn-Pleur
Gnathosten
Higher Jan
Stenetrioi
Aselloidea
Para-Abyss
Protojanir
Pseudojani
01110
??101
11110
00100
00000
11110
1?101
00100
11110
00000
11110
01000
00000
11110
00010
11111
11010
01000
11111
01000
00000
11010
01000
01000
1
0
1
1
0
1
0
1
Munn-Pleur
1
*--Higher Jan
I
I
I
*-----Gnathosten
requires a total of
14.000
steps in eaoh oharaoter:
o 1 2 3 4
5
6
1
1
7
8
9
*----------------------------------------1 0 1 1 1 1 1 1 1
01
101
0
1
1
1
1
best guesses of anoestral states:
o1
23 4 56789
01ＪＭｾ
? 1 0 0 0 0 ? 0 ?
101 0 0 0 0 0 0 0
382
Higher Jan
I
*-Munn-Pleur
1
*----Stenetrioi
1
*--------Gnathosten
/
/
requires a total of
15.000
steps in each character:
o 1 2 3 4
5
6
1
1
7
8
9
7
8
9
1
1
*----------------------------------------1 1 1 1 1 1 1 1 1
01
101
0
1
1
1
1
best guesses of ancestral states:
o1 23 4 5 67 89
*--------------------
01
O? 0 0 0 0 ? 0 0 .
101 0 0 0 0 0 0 0
Aselloidea
!
I
!
!
I
I
I
Gnathosten
!
I
I
I
I
Stenetrioi
1
1 Munn-Pleur
!
!
*--*--*--*--Higher Jan
/
/
requires a total of
15.000
steps in each character:
0 1
2
3 4
5
6
1
1
1
1
*-----------------------------------------
01
101
0
1
1
1
1
1
1
1
1
best guesses of ancestral states:
o1 2 3 4 5 6 7 8 9
*--------------------
01
0 0 0 0 0 0 0 0 0
101 0 0 0 0 0 0 0
1
383
Aselloidea
1
1 Higher Jan
I 1
I *-Para-Abyss
1 !
1 *--Munn-Pleur
1 1
1 *--
---Stenetrioi
1
I
I
*--*--- -·-----Gnathosten
requires a total of
15.000
steps in each character:
0123456789
*----------------------------------------1
1
1
1
1
1
1
1
1
01
101
a
1
1
1
1
1
1
best guesses of ancestral states:
a1 234567 8 9
ＪＭｾ
01
101
aaaaaaaaa
aaaaaaa
Aselloidea
!
1 Gnathosten
! 1
1 *-Protojanir
1 1
Stenetrioi
1 !
!
1 1
1 Munn-Pleur
1 1
I 1
1 1
1 1
1 ! Para-Abyss
I 1
1 ! 1
I
I
*-*----*--*--*--Higher Jan
requires a total of
16.000
steps in each character:
0123456789
01ＪＭｾ
101
a
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
.384
Aselloidea
I
I Higher Jan
I
I
I *-Para-Abyss
I
I
I *----Munn-Pleur
1
1
---Pseudojani
1 *
1
I
I *----------Stenetrioi
1
/
/
!
1. 1
Proto j anir
I
1
I
*--*------------*--Gnathosten
requires a total of
17.000
steps in each character:
o
1
2
.3
4
5
6
1
1
1
1
1
1
1
7
8
'9
*----------------------------------------01
1
1
1
1
1
1
1
1
2
101
best guesses of ancestral states:
o1
2 .3 4 5 6 7 8 9
*----------01
0 0 0 0 0 0 0 0 0
10! 0 0 0 0 0 0 0
APPENDIX 3
Output trom program CLIQUE, provided by J. Felsenstein,
University ot Washington.
Results ot two runs are given: 3A, Asellota
analysis; and 3B, Janiroidea analysis.
APPENDIX 3A:
Compatiblllty Analysis ot Asellota Data
""
Largest Clique program,
version 2.4
9 species, 16 character states
Species
Character states
Ancestor
Aselloidea
Protojanir
Gnathosten
Stenetr
Pseudojan
Munn-Pleur
Para-Abyss
Higher Jan
00000
00000
00101
00101
00100
00100
01110
11110
11110
00000
00000
00010
00000
01000
11111
11110
11110
11110
00000
00000
01000
01000
01000
01000
11010
11010
11111
0
0
0
0
1
1
1
1
1
Character Compatibility Matrix
1111111111111111
1111111111111111
1111111111111111
1111111111111111
1111111101111111
1111111111111111
1111111101111111
1111111111111111
1111010111111110
1111111111111111
1111111111111111
1111111111111111
1111111111111111
1111111111111111
1111111111111111
1111111101111111
385
386
Largest Cliques
Charaoters: (
6
1 2
3
4
5 6
7
8 10 11 12 13 14 15 16)
7 8 16 2 4 11 14 1 3 5 12 10 13 15
1--1-----1-----1--1--1--1--1--------------1--1
I 1
1
1 1 1 1 1-------! 1
1
1 1 1 1-------.:--------1-------------1---I 1
1---0-----0-------too
0
0--1
0
0--------------------1----------I
0
0
1----1---------- .• ---------------------------------
------0-----0---------
Higher Jan
Para-Abyss
Munn-Pleur
Pseudojan
Anoestor
Aselloidea
Protojanir
Gnathosten
Stenetr
387
APPENDIX 3B:
Compatibility analysis of the Janiroidea data.
Largest Clique program,
version 2.4
16 species, 30 character states
Species
-----
Pseudojan
Character states
---- .. _._--...-
00011 00000 00000 00000 00000 00000
"
Munn/Pleur 01110 01000 00101 00000 01000 00000
Para/Abyss 1111001000 10101 00000 01000 00000
Acanthasp
11110 11110 10101 00000 01000 01100
Dend/Haplo 11110 11100 00101 00000 01100 00000
Desmosomat 11110 11101 01101 01111 01111 10000
Haplonisc
11110 11100 00101 01000 01111 10000
Ischnomes
11110 11111 10101 01000 01110 10011
Janirellid 11110 11110 10101 00000 01110 11000
Janiridae
11110 11110 00010 00000 00000 00000
Joeropsid
11110 11100 00010 00000 01100 00000
Macrostyl
11110 11101 01101 01001 11110 00000
Mesosignid 11110 11110 00101 00000 01111 10000
Munnopsoid 11110 11110 10101 10000 01100 01100
Nannonisc
11110 11101 01101 01100 01111 10000
Thambemat
11110 11101 00101 00000 01100 00000
388
Character Compatibility Matrix
111111111111010111111011111111
111111111111111111111111111111
111111111111111111111111111111
111111111111111111111111111111
111111111111111111111111111111
111111111101010111111011111111
111111111111111111111111111111
111111111101010111111011111111
111111111001000101111000001111
111111110101111101111110001111
111110100011111101111100101111
111111111111111111111111001111
011110100111111111111101111111
111111110111111111111001111111
011110100111111111111101111111
111111111111111111111111111111
111111110001111111111111001111
111111111111111111101111111111
111111111111111111111111111111
111111111111111110111111001111
111111111111111111111111111111
011110100111101111111111111111
111111110101000111111111110011
111111110001111111111111110111
111111110010111101101111111111
111111110000111101101111110111
111111111111111111111100101111
111111111111111111111101111111
111111111111111111111111111111
111111111111111111111111111111
389
Largest Cliques
Characters: ( 1 2 3 4 5 6 7 8 10 12 14 16 18 19 21 27 28 29 30)
10 6 8 12 27 1 14 18 28 2 3 5 7 16 19 21 29 30 4
1--1--------1-----------1--------------------1------------ Desmosomat
1 1
1
1-- . - - - - - - - - - - - - - -.•... - Nannonisc
! 1
1----------------------------------1-------- Macrostyl
!
!
1------------ ----
ＱＭｾ
-------------------------1-1-- Ischnomes
Thambemat
1-- - - 0 - 0 - - 0 - - - - - 0 - 0 - - 1 - 0 - - - - - - - - Pseudojan
!
0 0
0------------------------------------ Munn/Pleur
1
0 0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - Para/Abyss
ＱＭｾ＠
ＭＱｾ
1
1
1---------------- --1
1---------------------------------------ＡＭＱｾ
!1-------------------------------1---ＭＮｾ
ｉＭｾ
ｉＭｾ
Munnopsoid
Acanthasp
Janirellid
Janiridae
Joeropsid
Dend/Haplo
Haplonisc
Mesosignid
Characters: ( 1 2 3 4 5 6 7 8 10 12 14 16 19 20 21 27 28 29 30)
10 6 8 12 27 1 14 20 28 2 3 5 7 16 19 21 29 30 4
1--1--------1----------1-------------------1-----------1 1
1
1----------------------1--------1-------------------------------------------! 1
! 1-----------------------------------------------1--1! 1-----------------------------------------------------1-----0--0--------0-----------0--0--1--0---------------0- - -----------------------1
0 0
!
0 0-.. ----------------- -.-----1----------1--------1----- ------1-------------!
1
1-----------------------------------------!
!-----------------1---------------------------------1
1------------------------------------
1---------------------------
I ｾＭ
ｴＭｾ＠
ｉｾＭ
Desmosomat
Macrostyl
Nannonisc
Ischnomes
Thambemat
Pseudojan
Munn/Pleur
Para/Abyss
Munnopsoid
Acanthasp
Janirellid
Janiridae
Joeropsid
Dend/Haplo
Haplonisc
Mesosignid
390
Characters: ( 1 2 3 4 5 6 7 8 12 14 16 17 18 19 21 24 28 29 30)
24 17 6 8 12 1 14 18 28 2 3 5 7 16 19 21 29 30 4
1--1--1
1 1 1
I 1 1
··.--1--------1--------------------1-----------1
1--------------------------------1------------------1---I 1 1------.....-----------------------1 "--11 1 1----- - - - - - - - - - - - - -- I
I
1
1-
Desmosomat
Nannonisc
Macrostyl
Ischnomas
Haplonisc
--- ..- - - - - - - - - - - - -..........------........--- Jan.irellld
. _ - - - - - - ＭＮｾ＠
Mesosign.id
!-------O--O----O-----------o--o--f--O------------------
too
Pseudojan
0-------------------------- Munn/Pleur
0 0----------------------------------------
!
ｐ｡ｲＯａｾｳ＠
! - - - - - - - - - - - - 1 - - - - - - - - - - - - - - - ... - - - - - Jan.1ridae
1--------------------------------- Joeropsid
1------------- ＭｾＱ
1
Munnopsoid
1----------------------------- Acanthasp
1----------------------------------------------------- Dend/Haplo
ｉＭｾﾷ
Thambemat
Characters: ( 1 2 3 4 5 6 7 8 12 14 16 17 18 19 21 27 28 29 30)
17 6 8 12 27 1 14 18 28 2 3 5 7 16 19 21 29 30 4
1-1--------1-----------1--------------------1-----------! 1
1
1--------------------------1-----------------------------------1-------1 1
1 1-···-----------------------------------------1--1--1 1---------------------------------------------------1-----0--0--------0-----------0--0--1--0--------------I
0 0
0--------------------------I
0 0----------------------------------------------1------------1-----------1--------------1--------------1
1
1-----------------------------1
1---·-------------------------------------1----···.· ·--------1--- ----------------------------1
1------------------------ -.
1----------------------------------------------------1--------------------------------------------------------ｬＭｾ
Desmosomat
Nannonisc
Macrostyl
Ischnomes
Haplonisc
Pseudojan
Munn/Pleur
Para/Abyss
Munnopsoid
Acanthasp
Janirellid
Janiridae
Joeropsid
Dend/Haplo
Mesosign.id
Thambemat
391
Characters: (
1
2
3 4 5 6 7 8 12 14 16 17 19 20 21 24 28 29 30)
24 17 6 8 12 1 14 20 28 2 3 5 7 16 19 21 29 30 4
Desmosomat
J 1 1
Macrostyl
1
ＱＭｾ
Nannonisc
! 1 1
ＱＭｾ
t 1
Is chnomes
ＱＭｾ
t 1 ＱＭｾﾷＬ
Haplonisc
I ＱＭＬＮｾ＠
Janirellid
ＭｾＬ
...
! ＱＭＮＬｾﾷ
Mesosignid
ＭＮｾＧ
Ｍｾ
1-------0--0-----_0-----0--0--1-_0----------- Pseudojan
o o
0-------------- .. ----------- Munn/Pleur
o 0------------- ------------------------------- Para/Abyss
1----------- --···---1------------------------------------ Janiridae
1 ..
Joeropsid
!----------------_. __ ..
Munnopsoid
ﾷＭｾＱＮ＠
Acanthasp
1-----------------------------Dend/Haplo
ｉＭｾＮｐ＠
1----- -_. ------- .----.----------------------------- Thambemat
ＡＭｾＱ
----------
. --..
.
------
1-----------..
. .----.,---------------____
Characters: ( 1 2 3 4 5 6 7 8 12 14 16 17 19 20 21 27 28 29 30)
17 6 8 12 27 1 14 20 28 2 3 5 7 16 19 21 29 30 4
1--1---------1-------------1--------------------1------------ Desmosomat
1
1
s tyl
1-----------------------1--------- Macro
1
Nannonisc
ＱＭｾ
J ＱＭｾ
Is chnomes
! 1------------------------------------------------------ Haplonisc
Pseudojan
ＱＭｏ｟ｾ
..
!
0 0
Munn/Pleur
0--------------------------------------- Para/Abyss
!
0 ｯｾＭ
Munnopsoid
ＱＭｾ
1
Acanthasp
1------------------------------ Janirellid
ＱＭｾ＠
Janiridae
ＱＭｾ
Joeropsid
ＱＭｾﾭ
Dend/Haplo
ｉＭｾ
Mesosignid
1--------------------------------------------------------- Thambemat
1--------------------------------------------------------!
!
.
1--0-----....------...---
392
Characters: (
24 26 25
1
2 3 4 5 6 7 8 14 16 18 19 21 24 25 26 28 29 30)
6 8 1 14 18 28 2 3 5 7 16 19 21 29 30 4
Desmosomat
!--1--1--1--------------1--------------------1-----------! 1 1 1
1--------------------------------- Nannonisc
! 1 1 1------------------------------------------------ Haplonisc
! 1 1 1------------------------------------------------ Mesosignid
! 1 1--------------------------------------------1--1--- Ischnomes
! 1 1--------------------------------------------------- Janirellid
! 1--------------------------------------------1--------- Macrostyl
ＡＭＰｏＱｾ
Pseudojan
!
0 0 0--------------------------------------- Munn/Pleur
!
0 0------------------------------------------ Para/Abyss
!--------------------1------------------------------------ Janiridae
!
1------------------------------------ Joeropsid
!--------------------------1--------------1--------------- Munnopsoid
!
1------------------------------ Acanthasp
!--------------------------------------------------------- Dend/Haplo
!--------------------------------------------------------- Thambemat
APPENDIX 4
Munnopsoid Analyses: Examples ot various tree topologies in the
output ot the program ITERMIX.
Eurycope
I Disconectes
I
I
*--Belonectes
I
I
1
*--*-----Tytthocope
1
*--- --Baeonectes
I
Amuletta
I
1 Ilyarachna
1
I
I
1
I
1 Bellibos
t
t
I
I
*--*--*--Betamorpha
1
t
t
1
*-----Btorthyngura
t
1
1
1
*--------------Paramunnopsis
1
Lionectes
1
1
1
!
1
1 Hapsidohedra
1
!
t 1
!
*--*--Lipomera
t
I I !
Mimocopelates
!
1
!
1
!
!
*--------*--Coperonus
I I !
!
1
*--------------Acanthocope
I
1
1
I
!
*-----------------Munnopsurus
I
!
!
I
*-------*---------------*-------------------Munneurycope
requires a total ot
73.000
weighted steps in each character:
o 1 2 3 4 5 678
ＪＭｾ
01
101
20!
2
1
301
3
2
2
2
4
2
2
2
4
4
2
2
1
2
4
2
2
2
1
393
9
2
2
4
2
2
1
3
5
4
394
Eurycope
I
!
I
Baeonectes
I
1 1 Belonectes
1
!
t
I
1
I
I
*--Disconectes
I
*--*--*-----Tytthocope
I
I
I
!
I
1
!
I
1
!
1
1
!
1
I
!
I
I
I
I
!
I
1
I
I
!
!
/
/
Munneurycope
!
1 Hapsidohedra
1
1
1 1 Lipomera
1 1 1
! *--*--Lionectes
1
1
! *--------Mimocopelates
t 1
! *-----------Coperonus
1 1
1 *--------------Acanthocope
!
!
*--*-----------------Munnopsurus
!
1
!
!
!
!
!
1
1
t
t
Paramunnopsis
1
I
1
!
!
!
1
!
t
Amuletta
!
*--Bellibos
!
*-----Ilyarachna
!
*--------Betamorpha
!
* - -----------*-----------------------*--*-----------Storthyngura
requires a total of
73.000
weighted steps in each character:
0123456789
*--.-----------------------------------222 2 2
01
101
201
301
2
1
3
224
224
2
4
1
2
2
242
2
2
1
354
4
1
395
Tytthocope
t
1 Belonectes
1
I
*--*--Disconectes
1
*--------Eurycope
!
*-.....
.-Baeonectes
I
I
1
1
I
I
!
I
!
I
I
I
1
!
1
I
1
1
I
!
!
I
I
!
!
1
t
/
/
Storthyngura
1
1 Amuletta
I 1
*--*-Betamorpha
!
*--------Ilyarachna
!
!
I
Paramunnopsis
I
*----------*--Bellibos
1
I
I
I
1
1
I
I
!
I
Munneurycope
1
1 Munnopsurus
1 I
I I Acanthocope
1 I I
1 I I Mimocopelates
I I 1 !
1
!
I
1
1
1
1
1 Hapsidohedra
!
!
I
I
I
I
I
I
!
!
!
I
1
1
!
1
!
1 Lipomera
I
!
I
*--*--*--Lionectes
!
1
!
*-------------*-----------------*--*--*--*-----------Coperonus
requires a total of
73.000
weighted steps in each character:
1
0
2
3
4 5 6
7
8
9
2
3
4
4
3
*----------------------------------------01
2
2
6 2
2
2
2
2
2
101
201
301
2
1
2
2
2
2
2
4
4
2
-5
2
1
2
1
1
396
Eurycope
!
Tytthocope
1
I Disconectes
1 !
*--*--*--Belonectes
1
*-----------Baeonectes
!
1
Munneurycope
!
!
!
!
!
!
!
Munnopsurus
1
1 1 Acanthocope
1 1 1
1 1 1 Lipolllera
1
1
1
I
I
I
1 1 I
I
1
1
*--Lionectes
I 1 I I
I I ! *-----Hapsidohedra
! I 1 1
! I 1 *-----Mimocopelates
II! !
1
!
!
1
I
I
*--*--*--*-----------Coperonus
1
1
I
Paramunnopsis
I
1
1
I !
1
!
!
!
!
!
!
I
1
I
I
1
I
I
I
I
/
!
*--Amuletta
I
*---Bellibos
I
1 *----Storthyngura
! !
I I
/
Betalllorpha
! 1
*--------------*---------------------*--*----------Ilyarachna
requires a total or
73.000
weighted steps in each character:
0123456789
*----------------------------------------2
22222
2
01
101
201
301
2
2
1
2
3
2
2
4
4
2
1
422
213
4
4
1
5
4
2
397
Baeonectes
1
1 Belonectes
1 1
1 *--Disconectes
1 1
*--*-----Tytthocope
1
*----------Eury,cope
t
1
I
I
I
I
!
1
I
!
1
!
!
!
I
!
I
!
I
I
!
1
1
!
!
1
!
/
/
Ilyarachna
1
*--Betamorpha
I
*-----Belllbos
t
*
----Amuletta
1
*-----------Storthyngura
1
*--
---------Paramunnopsis
I
1
Acanthocope
!
1
1
1 Lionectes
1
!
1
1 1 Lipomera
1
!
1
1
1 *--*--Hapsidohedra
1
1
I I !
!
1 *-------Mimocopelates
1
1
1 1
ＪＭｾｃｯｰ･ｲｮｵｳ＠
1
!
1
*----------------Munnopsurus
1
!
*--------------*----------------*--------------------Munneurycope
requires a total of
73.000
weighted steps in each character:
0 1 2 3 4 5 6
01ＪＭｾ
101
201
30!
2
1
3
•
2
2
2
2
2
2
2
4
4
2
2
1
2
4
2
2
2
1
7
8
9
2
2
3
4
4
5
1
4
2
398
Baeonectes
I
I Disconectes
1 1
! *-Belonectes
1
I
*--*-----Tytthocope
1
*--- - .. ---Eurycope
I
I
!
1
1
!
1
I
1
!
!
!
!
!
1
1
1
I
1
1
1
1
!
Bel1ibos
I
*--Paramunnopsis
!
J
!
1
r
!
1
Ilyarachna
1
J
1 Storthyngura
I
!
!
J
Acanthocope
1
1
1
!
!
1
1
!
1
1
1
1
1
1
1
I
1
I
1
I
I
*-----*--*--*--Betamorpha
J
I
Amuletta
1
1 Mimocopelates
1 I
! 1 Hapsidohedra
1 1 1
1 1 *--Lionectes
1 1 1
1 *--*-----Lipomera
1
1
*--*-----------Coperonus
1
*-----------------Munnopsurus
!
*--------------*-----------------*--------------------Munneurycope
requires a total of
73.000
weighted steps in each character:
0123456789
*----------------------------------------222 2 2 2 2 6 2
01
101
201
301
2
1
2
224
2 24
2
5
1
2
224
134
1
3
399
Eurycope
!
!
t
!
!
!
I
Disconectes
1
*-Belonectes
!
*-----Tytthocope
!
*-*--. .•
Baeonectes
I
I
1
Bellibos
1
*-Paramunnopsis
I
t
1
J
I
I
1
J
1
I
1
I
I
1
I
Betamorpha
I
1
1
1
*-Amuletta
1
J
1
*- .. --Storthyngura
1
1
*-----*--------Ilyarachna
I
J
1
1
I
I
Munnopsurus
I
!
I Mimocopelates
I
I !
!
1 ! Lipomera
I ! ! !
I I ! ! Lionectes
1
1
I
I
t
I
!
1
I
I
II!
*--*-*--Hapsidohedra
!
!
!
!
1
I
1
*-----------Coperonus
!
*--*--------------Acanthocope
1
t I l
/
/
*---------------*-- --------------*--------------------Munneurycope
requires a total of
73.000
weighted steps in each character:
0
ＪＭｾ
01
101
201
301
2
1
2
1
2
3
4
5
6
7
8
9
2
2
2
2
2
2
2
4
4
2
2
1
2
5
2
2
2
1
2
2
3
6
4
2
1
3
4
400
Eurycope
!
!
!
!
!
!
!
Baeonectes
J
!
!
!
!
Ty'tthocope
!
J
Disconectes
J
J
*--*--*--*--Belonectes
J
!
Bellibos
J
!
*--Paramunnopsis
J
1
J
J
1
1
!
J
/
Storthyngura
1
1
1
1
!
1 Amuletta
1 !
1 *-Ilyarachna
J 1
J
*-----*--*-----Betamorpha
!
!
!
1
I
1
1
1
1
1
1
1
1
1
1
1
/
J
J
1
1
I
1
1
1
1
1
Munneurycope
1
1 Munnopsurus
1 !
1 1 Lipomera
1 1 1
1 1 *--Lionectes
1 1 J
J 1 *-----Hapsidohedra
1 1 1
Coperonus
J t J
1 J J
J
J J *--------*--Mimocopelates
1 1 1
1
1
1
1
1
1
1
*--------------*-----------------*--*--*--------------Acanthocope
requires a total ot
73.000
weighted steps in each character:
0
1
2
3
4 5 6
ＪＭｾ
01
101
201
301
2
1
2
2
2
2
4
2
2
2
4
4
2
2
1
2
5
2
2
2
1
7
8
9
2
2
3
6
2
1
3
2
4
401
Disconectes
!
*-Belonectes
!
*-Tytthocope
t
*--------Eurycope
!
*--------Baeonectes
I
!
!
!
I
!
!
I
!
!
Paramunnopsis
I
I
I
I
1
I
!
I
I
J
Amuletta
I
Storthyngura
I
I
I
!
I
*--Bellibos
I
!
!
!
I
I
I
I
I
!
!
1
!
!
!
!
!
!
!
!
t
I
!
!
t
I
!
!
/
I
I
!
I
!
I
!
*--*--*--*-----Betamorpha
I
I
!
I
/
Ilyarachna
Munneurycope
!
!
I
!
!
!
!
!
Acanthocope
!
! Mimocopelates
! !
! *-Coperonus
! !
!!
Lipomera
!!
!
! I
I Lionectes
I I
! I
I
!
!
!
!
*--*-----*--*--Rapsidohedra
I
*--------------*-----------------*--*-----------------Munnopsurus
requires a total of
73.000
weighted steps in each character:
0 1 2 3 4 5 6
7
8
9
2
2
2
1
3
5
1
4
*----------------------------------------2
at
4 2 2 2 2 2 4 2
101
201
30!
2
1
3
2
2
2
2
4
4
2
1
4
2
402
Eurycope
!
!
!
!
!
Tytthocope
!
!
!
Belonectes
!
*--*--*--Disconectes
!
*-----------Baeonectes
1
!
I
!
!
!
!
!
!
I
I
1
!
1
!
1
1
I
!
!
!
!
!
!
!
!
!
/
/
Amuletta
!
*--Btorthyngura
1
*-----Ilyarachna
1
*--------Betamorpha
!
!
1
Bellibos
!
*-----------*--Paramunnopsis
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
Munneurycope
!
! Coperonus
! 1
! 1 Lipomera
! 1 !
! 1 ! Lionectes
! ! ! 1
! 1 *--*--Rapsidohedra
! 1 1
! *--*--------Mimocopelates
1 1
! *--------------Acanthocope
1 !
*--------------*-----------------*--*-----------------Munnopsurus
requires a total of
73.000
weighted steps in each character:
o 1 2 3 4 5 6
7
8
9
*-----------------------------------------
or
101
201
301
2
2
2
1
2
2
222
242
241
2
5
2
2
2
1
262
241
343
403
Munneurycope
!
! Acanthocope
1 I
t I Coperonus
1 I I
! I *--Mimocopelates
1 I I
Lipomera
! I I
!
1 ! I
1 1 1
*-Hapsidohedra
1
! 1 I
I *--*-----*-----Lionectes
1
1
ＪＭｾｍｵｮｯｰｳｲ＠
1
!
!
1
I
!
I
I
I
I
I
Storthyngura
!
t Amuletta
1 I
I I Ilyarachna
1 J I
t 1 *-Bellibos
I 1 I
*--*--*-----Betamorpha
I
*-----------------------*--------------Paramunnopsis
!
I
I
!
1
!
1
!
1
/
/
Baeonectes
1
1 Belonectes
1
!
1 *--Disconectes
1
!
*--*-----Tytthocope
1
ＪＭｾｅｵｲＬｹ｣ｯｰ･＠
requires a total of
73.000
weighted steps in each character:
0
1
2
3
4 5 6
ＪｾＭ
01
101
201
301
2
1
3
2
2
2
4
2
2
'2
4
4
2
2
1
2
4
2
2
2
1
7
8
9
2
2
3
4
2
2
1
4
5
George Wilson