A SYSTEMATIC REVISION OF THE DEEP-SEA SUBFAMILY
LIPOMERINAE OF THE ISOPOD CRUSTACEAN FAMILY
MUNNOPSIDAE
A Systematic Revision of the
Deep-sea Subfamily Lipomerinae
of the Isopod Crustacean Family
Munnopsidae
George D. E Wilson
UNIVERSITY OF CALIFORNIA PRESS
Berkeley Los Angeles London
BULLETIN OF THE SCRIPPS INSTITUTION OF OCEANOGRAPHY
OF THE UNIVERSITY OF CALIFORNIA
LA JOLLA. CALIFORNIA
Advisory Editors: Charles S. Cox, Abraham Fleminger,
Gerald L. Kooyman, Richard H. Rosenblatt (Chairman)
Volume 27
Approved for Publication June 25, 1986
UNIVERSITY OF CALIFORNIA PRESS
BERKELEY AND LOS ANGELES, CALIFORNIA
UNIVERSITY OF CALIFORNIA PRESS, LTD.
LONDON. ENGLAND
ISBN 0-520-09745-9
LIBRARY OF CONGRESS CATALOG CARD NUMBER: 88-37142
O 1989 BY THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
PRINTED IN THE UNITED STATES OF AMERICA
Library of Congress Cataloging-in-Publication Data
Wilson, George D. F.
A systematic revision of the deep-sea subfamily Lipomerinae of the
Isopod Crustacean family Munnopsidae / by George D.F. Wilson.
cm. - (Bulletin of the Scripps Institution of
P.
Oceanography, University of California, San Diego; v. 27)
ISBN 0-520-09745-9 (alk. paper)
1. Munnopsidae-Classification.
2. Crustacea-Classification.
I. Title. 11. Title: Lipomerinae of the Isopod Crustacean family
Munnopsidae. 111. Series.
QL444.M34W545 1989
595.3'72-dc19
88-37142
CIP
DEDICATION
This monograph is dedicated to the late Abraham Fleminger
whose contributions to my work and to crustacean systematics and
ecology will long be remembered.
George D. F. Wilson
June 1988
CONTENTS
List of Illustrations ......................................................................................... ix
xi
List of Tables ..................................................................................................
Acknowledgments ........................................................................................... xii
...
Xlll
Abstract ..........................................................................................................
INTRODUCTION
DEEP-SEA ISOPODS ..............................................................................
THE MUNNOPSIDS AND THE ILYARACHNID-LIKE
EURYCOPIDS .....................................................................................
MATERIALS AND METHODS ................................................................
SOURCES OF SPECIMENS ...................................................................
REPORTING AND USE OF RATIOS ....................................................
DEFINITION OF TAXA AND MORPHOLOGICAL TERMS ..............
PREPARATION AND ILLUSTRATION OF SPECIMENS ..................
PHYLOGENETIC TECHNIQUES ..........................................................
TAXONOMY OF THE LIPOMERINAE .................................................
DIAGNOSIS OF THE SUBFAMILY ......................................................
KEY TO THE GENERA AND DESCRIBED SPECIES
OF THE LIPOMERINAE ......................................................................
DESCRIPTION OF THE GENERA AND SPECIES
OF THE LIPOMERINAE ......................................................................
COPERONUS New Genus ..................................................................
Coperonus cornptus new species ....................................................
Coperonus nordenstarni new species ..............................................
HAPSIDOHEDRA New Genus ...........................................................
Hapsidohedra ochlera new species ................................................
Hapsidohedra aspidophora (Wolff 1962) ......................................
LIONECTES New Genus .....................................................................
Lionectes humicephalotus new species ...........................................
vii
...
Vlll
Contents
LIPOMERA Tattersall. 1905 ................................................................
Lipomera (Lipomera) lamellata Tattersall. 1905 ...........................
PARALIPOMERA New Subgenus .....................................................
Lipomera (Paralipomera) knorrae new species .............................
TETRACOPE New Subgenus ............................................................
Lipomera (Tetracope) cuwintestinata new species ........................
MIMOCOPELATES New Genus .........................................................
Mimocopelates longipes new species .............................................
Mimocopelates anchibraziliensis new species ...............................
PHYLOGENY AND CLASSIFICATION .................................................
TAXA USED ............................................................................................
CHARACTER ANALYSIS OF THE MUNNOPSIDAE .........................
LIST OF CHARACTERS ........................................................................
RESULTS OF THE PHYLOGENETIC ANALYSES .............................
DISCUSSION AND PROPOSALS FOR A REVISED
CLASSIFICATION ..............................................................................
APPENDIX 1
GENERAL MUNNOPSID EXTERNAL MORPHOLOGY.....................
APPENDIX 2
A GLOSSARY OF MORPHOLOGICAL TERMS ..................................
LITERATURE CITED ...............................................................................
LIST OF ILLUSTRATIONS
Figure 1. The morphological diversity in the munnopsids .........................
Figure 2. Dorsal views of several munnopsids ...........................................
Figure 3. Examples of Lipomerinae ...........................................................
Figure 4. Coperonus comptus n. gen.. n . sp...............................................
Figure 5. Coperonus comptus n . gen.. n. sp...............................................
Figure 6. Coperonus comptus n. gen.. n . sp...............................................
Figure 7. Coperonus comptus n . gen.. n . sp...............................................
Figure 8. Hapsidohedra ochlera n. gen.. n. sp...........................................
Figure 9. Hapsidohedra ochlera n . gen.. n . sp...........................................
Figure 10. Hapsidohedra ochlera n . gen.. n . sp...........................................
Figure 11. Hapsidohedra ochlera n . gen.. n. sp...........................................
Figure 12. Hapsidohedra ochlera n. gen.. n . sp...........................................
Figure 13. Hapsidohedra aspidophora (Wolff. 1962) ..................................
Figure 14. Lionectes humicephalotus n. gen.. n . sp.....................................
Figure 15. Lionectes humicephalotus n. gen.. n. sp.....................................
Figure 16. Lionectes humicephalotus n. gen.. n. sp.....................................
Figure 17. Lionectes humicephalotus n. gen.. n . sp.....................................
Figure 18. Lipomera (Lipomera)lamellata Tattersall. 1905 ........................
Figure 19. Lipomera (Paralipomera)knorrae n. subgen.. n . sp..................
Figure 20. Lipomera (Paralipomera) knorrae n. subgen.. n . sp..................
Figure 21. Lipomera (Paralipomera) knorrae n. subgen.. n . sp..................
Figure 22. Lipomera (Paralipomera)knorrae n . subgen.. n . sp..................
Figure 23. Lipomera (Tetracope)curvintestinata n. subgen.. n . sp.............
Figure 24. Hindgut form in two species of Lipomera ...................................
Figure 25. Lipomera (Tetracope)cuwintestinata n. subgen.. n . sp.............
Figure 26. Lipomera (Tetracope)cuwintestinata n . subgen.. n . sp.............
Figure 27 . Lipomera (Tetracope)cuwintestinata n . subgen.. n. sp.............
Figure 28. Mimocopelates longipes n. gen.. n. sp........................................
X
List of Illustrations
Figure 29. Mimocopelates longipes n . gen.. n . sp........................................
Figure 30. Mimocopelates longipes n . gen.. n. sp........................................
Figure 3 1. Mimocopelates longipes n . gen.. n . sp........................................
Figure 32. Mimocopelates longipes n . gen.. n. sp........................................
Figure 33. Mimocopelates anchibraziliensis n . sp.......................................
Figure 34. Mimocopelates anchibraziliensis n . sp.......................................
Figure 35. Mimocopelates anchibraziliensis n. sp........................................
Figure 36. A comparison of third pleopods of various Asellota ...................
Figure 37. A comparison of third pleopods of various higher
Janiroidea ................................................................................................
Figure 38. Cephalons of an acanthaspidiid and several munnopsids ...........
Figure 39. Cladogram of selected munnopsid genera using a priori
weights ....................................................................................................
Figure 40. Cladogram of selected munnopsid genera using successive
weights ....................................................................................................
Figure 41. Cladograms based on hypothetical relationships ........................
Figure 42. A tree based on 100 bootstrap estimates .....................................
Figure 43. Strict consensus trees of the Munnopsidae ..................................
Figure 44. The cladogram of the Lipomerinae ........................................ 117
LIST OF TABLES
Table 1. Classification of the munnopsids prior to the present
study ........................................................................................................
4
Table 2. A comparison of Ilyarachnidae with the Lipomerinae
....................
9
.........................................................
11
Table 3 . Abbreviations used in the text
Table 4 . Samples containing Lipomerinae
....................................................
12
Table 5. Samples collected by the Woods Hole Oceanographic
Institution ................................................................................................
14
Table 6. Distribution of character states in selected munnopsid
taxa ..........................................................................................................
106
Table 7. Character-taxon data matrix of selected munnopsids
108
......................
Table 8. A revised classification of the Munnopsidae
and the Lipomerinae ............................................................................... 119
ACKNOWLEDGMENTS
The study of deep-sea isopods is what it is today because of an important
monograph on the Asellota by 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.
The deep-sea isopod collection of Robert Hessler's laboratory, amassed
from Woods Hole Oceanographic Institution (WHOI) expeditions in the Atlantic,
was the primary source of material for this research. These samples were
collected by Howard Sanders, Robert Hessler, George Hampson, and J. Frederick
Grassle. Other sources for the specimens are listed in Tables 3 and 4. The
scientists directly involved with supplying some specimens are: J. Frederick
Grassle and Susan Brown-Leger (WHOI), Michel Segonzac (Centre National de
Tri d'Ocianographie Biologique), Linda Pequegnat (LGL Ecological
Associates), and Desmond E. Hurley (New Zealand Oceanographic Institute).
Various sections were read and commented on by members of the Scripps
Institution of Oceanography (SIO) and University of California, San Diego
(UCSD): Robert R. Hessler, William Newman, Richard Rosenblatt, William
Riedel, and Dan Lindsley (UCSD). This paper also benefited from discussions
with or reviews by Abraham Fleminger (SIO), Richard Brusca (San Diego
Museum of Natural History), Joseph Felsenstein (University of Washington),
Jean Snider (National Oceanic and Atmospheric Administration), David Thistle
(Florida State University), Mark Grygier, (National Museum of Natural History),
and Thomas Bowman (National Museum of Natural History). Sue Stultz (SIO)
helped convert microcomputer versions of the manuscript to the mainframe
word-processing system, and officiated over the printing of drafts. Kittie Kuhns
(SIO) was responsible for the editorial aspects of bringing this monograph to
print. I sincerely thank these people for their help and interest. This research
was supported by National Science Foundation Systematic Biology grants (DEB
80-07150, BSR 82-15942, and BSR 86-04573). Finally, I owe a great debt of
gratitude to my wife Kathy Fries-Wilson, who put up with me during the
research and writing, and helped with the editorial work.
xii
ABSTRACT
The fully natatory families of the janiroidean Asellota, the munnopsids
sensu lato, include a group of genera that blurs the distinction between the
Ilyarachnidae and the Eurycopidae. This work determines the interrelationships
of the ilyarachnid-like eurycopids, and shows that they are a monophyletic group.
In so doing, the family-level systematics of the munnopsids is revised. The
ilyarachnid-like eurycopids are assigned to a newly constituted subfamily, the
Lipomerinae, and five genera are described, four of which are new. A diagnosis
of the subfamily Lipomerinae with a key to the superspecific taxa is included in
the taxonomic part. One species in each superspecific taxon is fully described.
Coperonus n. gen. is a primarily Southern Hemisphere group with several species
in the south Atlantic and around the Antarctic continent. The most ilyarachnidlike genus is Hapsidohedra n. gen., which may have a cosmopolitan distribution.
Lionectes n. gen. is found in Antarctic waters. The pan-Atlantic genus Lipomera
Tattersall is further divided into three new subgenera. One of these subgenera, L.
(Tetracope)n. subgen., has a coiled gut, a rare occurrence among Crustacea. The
cosmopolitan Mimocopelates n. gen. is represented by a North Atlantic species
group based on the species M. longipes n. sp., and an equatorial species M.
anchibraziliensis n. sp. Character analyses of most munnopsid genera present
the characters that reveal relationships between taxa. The character states were
assigned evolutionary polarities by comparison with characters in a presumed
munnopsid sister group, the Acanthaspidiidae, and other janiroidean families.
Computerized phylogenetic analyses produced cladograms that were not fully
resolved, but had significantly lower homoplasy values than a tree based on
previous classifications. The Lipomerinae were the most significantly
monophyletic group of the munnopsid taxa, and a consensus tree of all possible
cladograms confirmed the monophyly of the Lipomerinae. Because the previous
classifications of the families were not consistent with the most parsimonious
cladograms, the following proposals are made: all munnopsid families should be
placed into one large family, the Munnopsidae; the Ilyarachnidae and the
Munnopsidae sensu strict0 should be demoted to subfamilial status; and the
current subfamilies of the Eurycopidae should be retained. This new
classification recognizes the monophyly of the Lipomerinae within the
Munnopsidae. Alternatives to this classification are discussed. Supporting the
text are appendices illustrating and defining morphological terms.
...
Xlll
INTRODUCTION
DEEP-SEA ISOPODS
Isopod crustaceans living in accessible environments like meadows or tide
pools are usually cryptic animals. To find them, one generally must look in
hidden places - under rocks, in cracks and crevices, or in the gills of fishes. But
in one environment, isopods live in the open. This is in the deep sea, the most
extensive environment on our planet (Sverdrup et al. 1942).
Unlike isopods living anywhere else, those of the deep-sea benthos are a
major feature of the biota. In most abyssal benthic samples, isopods of the
suborder Asellota are among the most abundant crustacean taxa, and often
account for a large fraction of all species present in an area (Sanders and Hessler
1969; Wilson and Hessler 1987). For example, isopods from the manganese
nodule province of the equatorial Pacific represent the third most abundant
macrobenthic taxon and their diversity possibly exceeds 125 species at one
location (Wilson, unpublished data). In one program 153 isopods were counted
from 15 quantitative samples from a 4500 m deep manganese nodule bottom
(Wilson and Hessler 1987). The samples held 59 species, a high species richness
considering that only 3.75 m2 of the sea floor was sampled (ibid.).
Deep-sea isopods do not resemble their cryptic shallow marine, freshwater,
and terrestrial counterparts. The archetypical isopod is dorsoventrally flattened
and has 7 pairs of similar legs, hence the translation of their name "like-footed."
A flattened body form is undoubtedly related to a cryptic lifestyle of creeping
underneath objects and into cracks and crevices. Deep-sea asellote isopods,
however, display a great variety of forms, including narrow walking-stick
creatures, species resembling little rocket ships, and highly modified swimmers.
Their varied body forms and high species diversity evince a great evolutionary
radiation, one apparently in full flower.
Extreme morphological differences among the families of the deep-sea
Asellota reflect evolutionary paths separate from other Isopoda: most of the
families of deep-sea isopods probably evolved in situ, not in shallow water
(Hessler and Thistle 1975; Hessler et al. 1979). The evolution of entire families
in the deep sea also has biogeographic consequences. These families and most of
their 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 new species are actively evolving (Wilson 1980a,
1983a), and species ranges are limited to small geographic areas and narrow
depth ranges (Wilson 1982b, 1983b).
Bulletin, Scripps Institution of Oceanography
Although deep-sea isopods are ecologically important and
biogeographically interesting, systematic knowledge on the most important
families is sparse. The primary deep-sea families belong to the suborder
Asellota, the systematics of which can best be described as superficial. The
Asellota have 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 species and morphological types in the deep sea (Menzies 1962;
Wolff 1962; Birstein 1963; Hessler and Sanders 1967; Hessler 1970; Hessler et
al. 1979). This interest has engendered a rapid accumulation of new species and
genera, described from deep-sea samples taken since the early 1960s. However,
no major reorganization of the suprageneric taxa has been attempted since the
landmark papers of Wolff (1962) and Menzies (1962). As a result, family-level
groups tend to be poorly defined because of the wide variety of taxa they include.
This problem is most acute in a group of families called the
"munnopsoidswlby Wilson and Thistle (1985): Munnopsidae, Eurycopidae, and
Ilyarachnidae. The munnopsids include taxa phylogenetically intermediate
between the Eurycopidae and the Ilyarachnidae (the genus Betamorpha Hessler
and Thistle 1975). In addition, a group of munnopsids very similar to the
Ilyarachnidae cannot be placed in that family because of the current
unsatisfactory definitions of the munnopsid families (Wilson and Hessler 1981).
These ilyarachnid-like Eurycopidae are the subject of this monograph. In it, I
propose a solution to the systematic problem they present. In so doing, I
consider the evolutionary paths taken by the deep-sea munnopsid isopods and
their ancestors.
THE MUNNOPSIDS AND THE ILYARACHNID-LIKE EURYCOPIDS
The munnopsid families of the 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). The success of the
munnopsids may be related to their primary specialization, the swimming habit.
Although primitive asellote isopods have lost the &cient crustacean ability to
swim, the munnopsids have an integrated set of adaptations that allows them to
swim rapidly and efficiently, but in a posterior direction. This ability resulted in
an important adaptive radiation - the evolution of numerous offshoots from
a basic swimming type - exemplified by the genus Eurycope (Fig. 1; see
Appendix 1).
The terms "mumopsoids" (Wilson and Thistle 1985) and "ilyarachnoid eurycopids" (Wilson and Hessler
1981) will not be used here because of potential confusion with superfamily-level m a . In their place, I
substitute the terms "mumopsids" and "ilyarachnid-like eurycopids." "Mumopsids" could be construed to
have two meanings in this paper, but is defined as having the broad meaning, i.e. including all three natatory
families. The ilyarachnid-like eurycopids are assigned to the mumopsid subfamily Lipomerinae Tattersall,
so these two terms are used synonymously.
'
Wilson:Revision of the Lipomerinae
Figure 1. A sampling of the morphological diversity present in the mumopsids, those Isopoda
Asellota with distinct natasomes. All are shown in dorsal view with anterior toward the top, not to
same scale. A, Eurycope. B, Munnopsurus. C , Acanthocope. D, Storthyngura. E, Ilyarachna.
F , Munnopsis. G, Syneurycope. H , Paropsurus.
Bulletin, Scripps Institution of Oceanography
TABLE 1.
Classification of the munnopsids (family Munnopsidae sensu lato
of Sars, 1869) prior to the present study.
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 Sars, 1899
Family Munnopsidae Sars, 1869 sensu Wolff, 1962
Genus Paramunnopsis Hansen, 1916
Family Eurycopidae Hansen, 1916
Subfamily Eurycopinae Hansen, 1916
Genus Eurycope Sars, 1864
Genus Betamorpha Hessler and Thistle, 1975
Subfamily Acanthocopinae Wolff, 1962
Subfamily Bathyopsurinae Wolff, 1962
Subfamily Syneurycopinae Wolff, 1962
Family Ilyarachnidae Hansen, 1916
Genus Ilyarachna Sars, 1864
Ilyarachnid-like Eurycopids, temporary group incertae sedis
Genus Lipomera Tattersall, 1905
(Taxa misplaced in the literature)
Ilyarachna aspidophora Wolff, 1962
Eurycope frigida Vanhoffen, 1914
Eurycope cf. frigida Nordenstam, 1933
This classification is extracted from: Bowman and Abele (1982); Hessler and Thistle (1975); and
Wilson and Hessler (1981). The classification of Schrarn (1986) is not used. Only the genera
discussed in the introduction are shown.
Wilson: Revision of the Lipomerinae
5
The munnopsids, a large family as originally conceived by G.O. Sars
(1883, 1899), are now classified into three separate families (see Table 1): the
Eurycopidae with several subfamilies, the Ilyarachnidae, and the Munnopsidae.
Some munnopsids have taken the swimming life to its logical extreme by being
holopelagic. Ilyarachnids, on the other hand, have specialized 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.
As presently constituted, the Eurycopidae are more difficult to place in this
functional scheme because many of the groups in the family have specializations
that resemble those found in the other two families. Some similarities are true
homologies, reflecting a common ancestry, such as the resemblance of the
eurycopids Betarnorpha and Amuletta to primitive members of the Ilyarachnidae
(Thistle and Hessler 1977; Wilson and Thistle 1985). Other similarities
undoubtedly are convergent on a common body form. Wilson and Thistle (1985)
point out that the present classification of the munnopsids is inadequate to
accurately classify taxa currently placed in the Eurycopidae.
Wilson and Hessler (1980, 1981) identified the group of genera within the
Eurycopidae that are distinctly ilyarachnid-like (Figs. 2, 3). A comparison of the
diagnostic characters of the Ilyarachnidae (Wolff 1962) with the features of these
eurycopids (Table 2) reveals substantial similarities between the groups. The
overall shape of the natasome and the cephalon are most compelling. In the
current literature, these ilyarachnid-like eurycopids are only a collection of
species and genera with no taxonomic status. On a purely typological basis
(using similarities only), they should be classified with the Ilyarachnidae. The
similarities, however, may result from convergence of unrelated taxa to a
common body form, thus decreasing the naturalness and usefulness of such a
phenetic classification. Therefore, these character complexes are examined in
more detail.
The ilyarachnid-like eurycopids first appear in the literature with the
description of Lipornera larnellata Tattersall, 1905 (1905a,b). Related species
are Eurycope frigida Vanhoffen, 1914, E. cf. frigida Nordenstam, 1933,
Ilyarachna aspidophora Wolff, 1962 (see Wilson and Hessler 1981). Species of
this group appear in more than 60 samples of deep-sea isopods from the North
and South Atlantic oceans (see next section). As in other deep-sea Asellota, the
ilyarachnid-like eurycopids display high latitude emergence. The ilyarachnidlike eurycopids need revision because their numerical and biogeographic
importance has received little attention in the literature.
Morphologically, eurycopids that look like ilyarachnids are fairly diverse.
Although Ilyarachna-like features are found in all of them, the ilyarachnid-like
Eurycopidae 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
6
Bulletin, Scripps Institution of Oceanography
Figure 2. Dorsal views of several munnopsids to illustrate an ilyarachnid-like appearance. Not to
same scale. A, Eurycope. B, Ilyarachna. C, Amuletta. D, Lipomera. E, Mirnocopelates n. gen.
Not to same scale.
Wilson:Revision of the Lipomerinae
7
the form of the cephalon; they also have definable differences in the uropods and
pleotelson. In this paper, Lipomera Tattersall, 1905, is redescribed, and the
species of this genus are divided into three subgenera. Four new genera are
erected to contain the remaining species originally classified by Wilson and
Hessler (198 1) as the ilyarachnid-like Eurycopidae. These genera are grouped in
the munnopsid subfamily Lipomerinae Tattersall, 1905 (originally proposed as a
family. Finally, the phylogeny of the Lipomerinae (= ilyarachnid-like
eurycopids) is studied to discover their relationship to the other natatory taxa.
Because the Lipomerinae confound the distinction between the Ilyarachnidae and
the Eurycopidae, this phylogenetic investigation must also include munnopsid
evolution. The result is a new classification of the natatory deep-sea Asellota
Janiroidea that uses Sars' original broad definition of the Munnopsidae.
Bulletin, Scripps Institution of Oceanography
Figure 3. Examples of ilyarachnid-like eurycopids (Lipomerinae) in lateral view, with anterior to
the right. A, Coperonus n. gen. B, Lionectes n. gen. C, Hapsidohedra n. gen. D, Lipomera
(Paralipomera) n. subgen. E , Mimocopelates n. gen. F , Lipomera (Tetracope) n. subgen. G,
llyarachna (forcomparison). Not to same scale.
Wilson:Revision of the Lipomerinae
TABLE 2.
A comparison of the characters from the diagnosis of the
Ilyarachnidae (Wolff 1962) with the Lipomerinae.
Ilyarachnidae
Lipomerinae
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 I11 and IV with short basis*
Uropods flattened, oval; setiferous protopod; reduced rami
"+" = Has similar character. "-" = No similar character. Characters found in all munnopsids
omitted. * = Character is considered by Thistle and Hessler (1976) to be the principal diagnostic
character separating the Ilyarachnidae from the Eurycopidae.
MATERIALS AND METHODS
Several techniques have been applied to the study of the ilyarachnid-like
eurycopids, and the munnopsids in general. Often the taxonomic literature is
unclear about a particular term, or procedures that are used to generate
descriptions, hypotheses of relationship, or classifications. My procedures are
explained below, and many of the taxonomic terms are defined in a glossary.
The phylogenetic study uses techniques of numerical cladistics, a field in which
controversy arises frequently.
SOURCES OF SPECIMENS
The specimens used in this study came from a variety of sources (Tables 4,
5, abbreviations in Table 3). The principal source was a series of deep benthic
sampling transects in various basins of the Atlantic Ocean. These samples were
collected by the Woods Hole Oceanographic Institution (WHOI) scientists under
the direction of Howard Sanders, Robert Hessler, and J. Frederick Grassle.
These samples include specimens from the Gay Head-Bermuda Transect, off
New England (Sanders et al. 1965; Hessler and Sanders 1967). An important
collection of Antarctic isopods was provided by John Rankin, University of
Connecticut, from samples collected in the Weddell Sea during 1968 and 1969
(68Rankin and 69Rankin samples). Specimens from the South Shetland Islands
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
Peninsula (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 two samples from Hjeltefjord, Norway (HMB samples).
Recent studies of slope fauna off the eastern United States, directed by James
Blake and Nancy Maciolek-Blake of Battelle New England Marine Research
Laboratory (U.S. Department of the Interior Minerals Management Service
[MMS] contract 14-12-0001-30064), have provided 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 (LGL1, LGL2, LGL3 samples) was provided by Linda Pequegnat, LGL
Ecological Research Associates (MMS contracts 14-12-0001-30046 and
14-12-0001-30212). Specimens collected from slope depths off New Zealand
(NZOI samples) were kindly sent by Desmond Hurley, New Zealand
Oceanographic Institute, and Roger Lincoln, British Museum, Natural History.
These latter specimens are mentioned only briefly and will be the subject of a
future paper describing New Zealand munnopsids.
Wilson: Revision of the Lipomerinae
TABLE 3.
Abbreviations used in the text.
Sources of Specimens
BAT
HMB
INCAL
IODal
LGL
NZOI
RANKIN
WHO1
Battelle New England Marine Research Laboratory
Marine Biology Course at Herdla, Norway
Joint European Expedition "Intercalibration"
Institute of Oceanography, Dalhousie
LGL Ecological Research Associates
New Zealand Oceanographic Institute
John Rankin Samples, Weddell Sea
Woods Hole Oceanographic Institution
Depositories of Specimens
BMNH
MNHN
SIO
USNM
ZMUC
British Museum (Natural History)
Museum National d'Histoire Naturelle, Paris
Robert Hessler collection,
Scripps Institution of Oceanography
United States Museum of Natural History
Zoological Museum, University of Copenhagen
Other Abbreviations
bl
Body length, measured from frons to pleotelson tip
inds
Individuals, usually reporting number used in a
measurement
TABLE 4. Samples containing Lipomerinae.
Genus*
Program and Station Number
Location
H*
C*
R/V Galathea sta. 639 (wolff 1962)
Swedish Antarctic
Expedition sta. 34 (Nordenstam 1933)
R/V Helga station (Tattersail 1905a.b)
Gauss Station (Vanhoffen 1914)
68Rankin OOOlES
68Rankin OOOlAD
68Rankin 0018ES
68Rankin 0055SBT
69Rankin 001AD
BAT MI-13-1-7
BAT S1-3-1-3
BAT S2-3-2-(1-9)
HMB Beyer 7-8/VII/78
HMB RPsled 4/VII/78
INCAL DS 13
INCAL OS04
INCAL WS03
IODal6
IODal7
IODal13
LGLl C1/4
LGL5 WCO515
LGL5 WCO7/3
Off New Zealand
South Georgia
Off Cumberland Bay
Porcupine Bank
Eastern Antarctica
S. Weddell Sea
S. Weddell Sea
S. Weddell Sea
W. Weddell Sea
S. Weddell Sea
Off Delaware Bay, USA
Off Cape Lookout, USA
Off Cape Lookout, USA
Hjeltefjord, Norway
Hjeltefjord, Norway
NE Atlantic Ocean
NE Atlantic Ocean
NE Atlantic Ocean
S. Shetland Isl.
S. Shetland Isl.
S. Shetland Isl.
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
LP1**
C*, LN*
C
C
C
C
C, LN
LP3
LP3
LP3
LP3
LP3
M1
M1
H
C
LN
C, LN**
L3
L3
L3
Midpoint Latitude
Midpoint Longitude
Midpoint Depth (m)
TABLE 4. (continued)
Genus*
Program and Station Number
Location
H
H
H
H
LGLl C4
LGL2 C2
LGL2 C4
LGL3 C3
LGL3 C7
LGL3 C9
LGL4 E2
LGLS WC06
LGL5 WCl 1
LGL2 E4
LGL2 W2
LGL2 W3
LGL3 C8
LGL4 E3a
LGL4 E3b
LGLS WC 12
NZOI F7 19
NZOI E753
NZOI F9 11
NZOI P939
NZOI S 147
NZOI S 153
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
N. Gulf of Mexico
Off New Zealand
Off New Zealand
Off New Zealand
Off New Zealand
Off New Zealand
Off New Zealand
H
H
H
H
H
LP2
LP2
LP2
LP2
LP2
LP2
LP2
M2
M2
M2
M2
M2
M2
Midpoint Latitude
Midpoint Longitude
Midpoint Depth (m)
Descriptions and abbreviations of programs given in text. In trawl samples that have different start and finish positions, only the midpoints for the both
latitudes, longitudes, and depths are given. All positions are rounded off to the nearest minute. The abbreviations for the genera are as follows: C, Coperonus
n. gen.; H, Hapsidohedra n. gen.; LN, Lionectes n. gen.; LP1, Lipomera (Lipomera); LP2, Lipomera (Paralipomera) n. subgen.; LP3, Lipomera (Tetracope) n.
subgen.; MI, Mimocopelates longipes n. gen., nsp. species group; M2, Mimocopelates anchibraziliensis n. gen., nsp. species group. Abbreviations with an
asterisk (*) indicate a type locality. Abbreviations with a double asterisk (**) indicate a type locality for a generic type. All samples except those collected by
the Woods Hole Oceanographic Institution programs (see Table 5).
TABLE 5.
Samples collected by the Woods Hole Oceanographic Institution.
Genus*
Program and
Station ~ i m b e r
M1
M1
M1
M1, LP3
M1
M1
LP3
M1
M1
MI
LP2
M1
M2
C, M2
LP2, M2
LP2, M2
LP1
H
MI, LP3**
WHOI F1
WHOI 64
WHOI 66
WHOI 73
WHOI 85
WHOI 103
WHOI 119
WHOI 126
WHOI 128
WHOI 131
WHOI 142
WHOI 156
WHOI 159
WHOI 162
WHOI 167
WHOI 169
WHOI 180
WHOI 189
WHOI 209
Location
Midpoint
Latitude
Midpoint
Longitude
Midpoint
Depth (m)
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
E. Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Gay Head-Bermuda Transect
Off Sezegal, Africa
Near St_.?eter & St. Paul Rocks
Off Brazil
Off Brazil
Off Brazil
Off Brazil
Off Walvis Bay
Off Walvis Bay
Gay Head-Bermuda Transect
39" 47' N
38" 46' N
38" 47' N
39" 47' N
37" 59' N
39" 44' N
32" 16' N
39" 37' N
39" 47' N
36" 29' N
10" 30' N
00" 46' S
07" 58' S
07" 59' S
07" 54' S
08" 03' S
22" 54' S
23" 00' S
39" 47' N
70" 45' W
70" 06' W
70" 09' W
70" 43' W
69" 26' W
70" 37' W
64" 32' W
66" 46' W
70" 45' W
67" 58' W
17" 52' W
29" 26' W
34" 22' W
34" 06' W
34" 17' W
34" 24' W
13" 32' E
12" 45' E
70" 49' W
1500
2886
2802
1400
3834
2022
2159
3806
1254
2178
1710
3459
887
1493
975
587
205
1011
1597
TABLE 5. (continued)
Samples collected by the Woods Hole Oceanographic Institution.
Genus*
Program and
Station Number
Location
Midpoint
Latitude
Midpoint
Longitude
Midpoint
Depth (m)
MI, LP3
C**
C
C
H, M1
C' H
MI
M1
M1
H**
LP2
M1
MI**
M1
H, M1
M1
H, M1
H,LP2**,Ml
WHOI 210
WHOI 236
WHOI 237
WHOI 239
WHOI 243
WHOI 245
WHOI 287
WHOI 291
WHOI 293
WHOI 295
WHOI 297
WHOI 299
WHOI 321
WHOI 326
WHOI 328
WHOI 330
WHOI 334
WHOI 340
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
N E Atlantic Ocean
NE Atlantic Ocean
NE Atlantic Ocean
NE Atlantic Ocean
Central North Atlantic Ocean
NW Atlantic Ocean
39" 43' N
36" 28' S
36" 3 3 ' s
36" 49' S
37" 37' S
36" 56' S
13" 16' N
10" 06' N
08" 58' N
08" 04' N
07" 45' N
07" 55' N
50" 12' N
50" 05' N
50" 05' N
50" 43' N
40" 43' N
38" 16' N
70" 48' W
53" 32' W
53" 23' W
53" 15' W
52" 24' W
53" 01'W
54" 53' W
55" 14' W
54" 04' W
54" 21'W
54" 24' W
55" 42' W
13" 39' W
14" 24' W
15" 45' W
17" 52' W
46" 14' W
70" 21' W
2044
508
1002
1670
3819
2707
4957
3864
1487
1011
516
2009
2879
3859
443 1
4632
4400
3310
See Table 4 for explanation.
Bulletin, Scripps Institution of Oceanography
REPORTING AND USE OF RATIOS
In this paper many ratios are used for descriptions. To avoid repeating the
word "times," ratios are reported as a multiplier of an object of a telegraphic
phrase 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
"palp second article 0.86 mandibular body length" means "the second article of
the palp is 0.86 times the length of the mandibular body." Mathematically, these
examples are equivalent to the equations "L = 2.2W" and "P = 0.86M,"
respectively.
Ratios provide a precise, unambiguous description of shape as well as
normalizing the size of an appendage or segment to the overall size of the
specimen. Ratios are derived from measurements taken using a camera lucida on
the microscope, or from camera lucida drawings. The precision of the ratios is
reduced in most cases to 2 significant figures to accommodate individual
variation and measurement error. Statistical accuracy, however, is not implied by
the use of ratios because of small sample sizes. If the ratios are derived from
more than one specimen, the number is reported parenthetically after the ratio.
Nouns are used as modifiers of other nouns, a practice that improves the
readability of the necessarily dense telegraphic style used to describe the species.
Used in this way, the modifier nouns identify larger sets of characters to the left
so that the reader will be taken from general to specific, e.g. "male pleopod I
distal tip inner lobe . . ." Each set indicated by a noun may include a modifier to
specify position or appendage number.
DEFINITION OF TAXA AND MORPHOLOGICAL TERMS
Species are identified using the variation within and between samples of
similar animals (Wilson and Hessler 1980; Wilson 1982a). For this paper,
however, species-level taxa were not examined in detail, because my goal was to
elucidate the higher level taxonomy of the ilyarachnid-like eurycopids. In fact,
some species may include complexes of cryptic species; Mimocopelates longipes
n. gen., n. sp., is suspected of being one such case because it has a broad
distribution similar to the Eurycope complanata complex (Wilson 1982b). In
such cases, individuals from other than the type locality are only provisionally
referred to the species. These species problems are left for future study.
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).
External morphology of munnopsids is illustrated in Appendix 1 and a glossary
of morphological terms used in this work is provided in Appendix 2. Figure 4
illustrates 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 cephalon, vary considerably
among the janiroidean isopod families, and may express important differences in
Wilson:Revision of the Lipomerinae
17
feeding life styles between groups of species. The natasomal characters, such as
the paddlelike swimming legs, are unique to (a synapomorphy of) the munnopsid
taxa, and indicate the locomotory styles of their bearers. The natasome shows
much variation among these taxa (for example, see Fig. I), but is constant within
species groups. As such, the natasome characters are ideal for generic definition
within the munnopsids. 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. This
system defines genera as distinctive groups of species, separated from other such
groups by distinct morphological gaps (Mayr 1970). New genera are
monophyletic clades of similar species, and existing genera are assumed to be
monophyletic in the phylogenetic analyses.
PREPARATION AND ILLUSTRATION OF SPECIMENS
All specimens are stored in 80% ethanol. For study, they were placed on
depression slides in ethylene glycol. 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 were originally done in pencil, and then inked by tracing onto
translucent vellum. The illustrations cannot include all details of the animals,
although effort was made to include all major surface structures, including 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 circular, u-shaped, or v-shaped marks (e.g., Fig.
6D), open in the direction of the setal shaft. This form of setal row illustration
has been used because the plumose setae of the natapods are typically collected
into a mass (see Wilson and Hessler 1980, their figure 13A). The typical
representation of a setal row, a line connecting the tips of the setae not shown, is
difficult to accurately represent; thus, representative setae are shown without tip
indications for unillustrated setae. Some setae, such as plumose setae and broom
setae, have many fine setules that, do not reproduce well if all are illustrated;
therefore, setules on setae are sparsely illustrated. Some cuticular structures,
generally best studied with a scanning electron microscope, were often prominent
on the specimens and were drawn partially to accentuate cuticular form. Most
detail in the drawings represents surface structures. Frequent exceptions are the
musculature and sperm tubes of male pleopods I and 11, and sometimes structures
on the mandibles. Subsurface detail is shaded, or represented by dashed lines. If
not otherwise noted, the orientation of the illustrations is as follows: pereopods
are illustrated in lateral view; maxillulae, maxillae, maxillipeds, and pleopods are
illustrated in ventral view; antennulae are illustrated in dorsal view.
Bulletin, Scripps Institution of Oceanography
PHYLOGENETIC TECHNIQUES
The phylogenetic analysis was a two-step process: character analysis and
computer-assisted estimation once a data set was chosen. The direct approach of
leaving the derivations of the characters undetermined, and using the outgroup
taxa in a single-step phylogenetic analysis proved to be inefficient because many
characters were found to be unsuitable for the chosen systematic level. To
reduce the number of possible misinterpretations, I evaluated each character
separately with respect to the munnopsids and the outgroup taxa: the Janiridae,
the Janirellidae, and the Acanthaspidiidae (see Phylogeny and Classification
section for explanations of taxon choice). The numerical techniques are
discussed first because of their use in the character studies.
Numerical Analysis
Numerical phylogenetic analysis (reviewed in Felsenstein 1979, 1982) was
accomplished with two different systems: PHYLIP versions 2.7 - 2.8
(PHYLogeny Inference Package; Felsenstein 1985) and PHYSYS (computer
assessment of phylogenetic relationships system, designed and written by J.S.
Farris (described in Luckow and Pimentel 1985). PHYLIP was used on a IBM
XT microcomputer. PHYSYS, which is installed on a CYBER 750 in the
California State University central computer network, was accessed over
telephone lines via modem. A third analysis package, PAUP (Phylogenetic
Analysis Using Parsimony, by D. Swofford), became available during the final
stages of editing this paper, and was not used for most analyses. PAUP was only
used to verify the primary results of this paper: the monophyly of the
Lipomerinae, the relationship of the Lipomerinae to the other munnopsids, and
the improved parsimony values gained by including all munnopsids into a single
family, rather than dividing them into three distinct monophyletic taxa of
previous classifications.
PHYLIP has a variety of programs for determining phylogenies. MIX
allows one of two parsimony algorithms for each character independent of the
others: the Camin-Sokal method (Camin and Sokal 1965) and the Wagner
method (Eck and Dayhoff 1966; Kluge and Farris 1969; Felsenstein 1978, 1979,
1981). MIX version 2.8 has a global branch-swapping routine that improves the
probability of finding a tree with the fewest character changes. MIX is sensitive
to taxon input order and must be run numerous times with different orderings. A
modified version of the program, ITERMIX, randomly ordered the taxa into as
many data sets as desired, and then evaluated all resulting data sets. Typically,
"a" parsimonious tree was found within 5 iterations of MIX, but often different
topologies with the lowest number of character changes appeared in runs of
30-50 iterations. For small data sets, the PHYLIP program PENNY, which
employs a "branch and bound" algorithm (Hendy and Penny 1982), was used to
find all parsimonious trees. During the creation of a cladistic hypothesis from the
Wilson: Revision of the Lipomerinae
19
literature, PENNY was effective for establishing the parsimonious arrangements
of undefined clades of munnopsid taxa. PENNY could not be used for the
complete set of munnopsid taxa because the total number of possible trees is
astronomically high.
PHYSYS was accessed to use the WAGNER tree builder with global
branch swapping (WAG.S) and the WISS tree builder (Weighted Invariant Step
Strategy, described in Farris et al. 1970). The latter program calculates the most
parsimonious trees on the basis of irreversible evolution, similar to the CaminSokal technique in PHYLIP. During the analyses, it was discovered that WAG.S
is also sensitive to the input order of the taxa, even though publications imply
otherwise (Luckow and Pimentel 1985). Therefore, PHYSYS runs were done on
data sets that generated minimum-evolution trees in PHYLZP MIX. WAG.S or
WISS each use only one parsimony method; because of this limitation, their
results were considered advisory, and they were primarily used to derive weights
for the characters.
Character Analysis
Polarities of character transformations were determined by outgroup
analysis (Watrous and Wheeler 1981; Maddison et al. 1984). Detailed analyses
of each character and the outgroup taxa are discussed in the section on
phylogenetic analysis. Multistate characters were coded into binary characters
using the method developed by Kluge and Farris (1969), implemented in
PHYLIP by the program FACTOR. Some characters, however, had uncertain
transformation series. Preliminary runs of ITERMIX were made to test all
possible transformations to find those that generated the trees with the fewest
character changes. These initial runs were done in the more restrictive CaminSokal method, with an ancestral rooting of all the characters and no weights for
the different characters. Each of these data sets was run at least 10 times,
although the more promising combinations were run 30-40 times. Once the most
likely character transformations were found, character weights and parsimony
methods were assigned to the data set for final evaluations.
Characters that introduced a large number of steps into the preliminary
trees were re-evaluated to determine their interpretation. During this process
many characters were rejected as useful at the systematic level of munnopsids.
This process resembles compatibility analysis (Felsenstein 1982; Meacham and
Estabrook 1985) because it uses those characters that agree on a particular form
of the phylogeny. Nevertheless, some homoplastic characters were retained,
because they helped resolve some branches, and because they were stable within
most taxa. Convergences and parallelisms found in the preliminary trees were
not divided into separate characters to improve parsimony levels unless some
rationale external to the phylogenetic study for recoding them was found. For
example, if an apomorphy appeared independently in two or more separate
20
Bulletin, Scripps Institution of Oceanography
clades, this character state would not be classified as two separate characters
unless the states carried by the separate clades were morphologically
nonhomologous. In this study, recoding was not done because many apparent
homoplasies, such as the parallel loss of multiple plumose setae on the third
pleopod, could not be discerned as morphologically different in the separate
clades.
For the final analyses, each character was classified as to whether or not
reversals were probable. Reversals were considered possible in characters based
on simple changes in length or shape. These characters were analyzed with the
Wagner method. Reversals were considered unlikely if the characters involved
the following general aspects: fusion, extreme reduction, or loss of segments; and
appearance of a new complex morphology. The nonreversible characters were
analyzed with the Camin-Sokal method. This method, applied at a higher
systematic level to the reduction characters (see below), would resemble the
Dollo parsimony method (Felsenstein 1979) where a character is derived only
once, and then lost many times. Within the munnopsids, however, such
characters are plesiomorphies, making the Camin-Sokal method appropriate for
their analysis. (See the section on phylogenetic analysis for a discussion of the
derivation of each character.)
Character Weighting
Although character weighting is controversial (Patterson 1982), I have used
it here for practical reasons: some homologies are more likely to have been
misinterpreted than others, and should have a lesser effect on the analysis. For
example, regressive (loss) characters should have an a priori low weight because
of their potential for appearing many times independently but nevertheless being
indistinguishable (Mayr 1970). Some characters are likely to evolve faster than
others, and therefore may be less useful in evaluating phylogenies; if one can
apply higher weights to those characters that change the fewest number of times,
the resulting cladogram is more likely to resemble the true phylogeny.
The weighting schemes in PHYLIP permit either direct weighting or the
threshold technique (Felsenstein 1981), which causes characters to be ignored in
the construction of a phylogeny above a chosen number of character changes.
This latter method allows a gradient between parsimony and compatibility
techniques for generating trees. An a priori weighting was applied to the final
series of analyses as follows. Characters hypothetically derived only once were
given a weight of 2, and reduction apomorphies were given a weight of 1. A
weighting based on successively derived, mean character consistencies (Farris
1969), which depend on their relationship to the overall phylogeny, was used to
complement the a priori weights. The successive weighting algorithm is
implemented in PHYSYS and can be applied to any data and tree form. A
munnopsid data-set order found to produce a parsimonious tree in ITERMIX was
Wilson:Revision of the Lipomerinae
21
converted to PHYSYS format. The PHYSYS WAG.S and WISS tree builders
were both used in the successive weighting algorithm to derive two sets of
character weights, which varied between 1 (the most consistent characters) and 0
(a completely informationless character within the phylogeny), with the most
common weights being 1 and 0.5. These weights were then used in a final
PHYLIP data set which applied the WISS weights to the Carnin-Sokal characters
and the WAGNER weights to the Wagner characters. The weights were
converted to the PHYLIP integer format by multiplying them by 4 and then
rounding upward to the nearest integer. Thus, PHYSYS weights of .76-1.0 had a
PHYLIP weight of 4, weights of 0.26-0.5 became 2, etc.
Confidence Limits. The most parsimonious cladograms, those with the fewest
character changes, may not be the best estimates of the "true" cladogram, simply
because evolution is not constrained by parsimony. Bootstrap confidence
estimates of monophyletic groups were derived by the PHYLIP program BOOT
(Felsenstein, 1985). BOOT gives a rough estimate of statistical significance of
monophyletic groups by providing a frequency of their appearance in iterated
phylogenetic analyses with randomly differing combinations the character set
with randomly varying weights. Groups based on only one character often fare
poorly in such analyses, especially if the data are "non-Hennigian" (containing
many incongruent characters)(ibid.).
TAXONOMY OF THE LIPOMERINAE
Isopoda, Asellota, Janiroidea
Family Munnopsidae Sars, 1869 sensu lato
Subfamily Lipomerinae Tattersall, 1905 new definition
DIAGNOSIS OF THE SUBFAMILY
Munnopsidae with following characteristics: Cephalon broader than long,
robust, lacking rostrum, with high flattened frontal arch or with obsolete frons.
Natasome (pereonites 5-7, pleotelson) triangular in dorsal view, broader than
ambulosome. Pereonite 7 reduced or absent, fused medially on dorsal surface in
all except Coperonus. Pereopod I1 not prehensile, similar to other walking legs.
Pereopods 11-IV approximately same length or slightly increasing in length
posteriorly. Bases of pereopods I-IV subequal. Pereopod VII reduced to
walking-leg state, rudimentary, or absent. Pleopods 11 of female covering anus.
Pleopod I11 with 3 plumose setae on endopod, 2-3 plumose setae on exopod.
Pleopod IV with 1 plumose seta on exopod. Uropods variously shaped: normal
with broad protopod, enlarged and leaflike, or tiny.
Wilson:Revision of the Lipomerinae
Figure 4. Coperonus comptus n. gen., n. sp. A-B, holotype male, lateral and dorsal views, scale
bar 1.0 mm. C-F, cephalon, paratype brooding female, b12.8 mm, antennula and antenna removed
from one or both sides to show frons. C, lateral view. D, frontal oblique view. E, anterior view.
F, ventral view, maxilliped removed to show shape of mandibles and ventral cephalon.
G, natasome, paratype male, b12.9 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; 1= labrum; m = mandible; mxI = maxillula; mxII = maxilla; ok = oral knob
(supports maxillipeds above mouthparts shown); p = paragnaths (shaded with dots); plI = male
pleopod I; plII = male pleopod 11; ur = uropod.
24
Bulletin, Scripps Institution of Oceanography
KEY TO THE GENERA AND DESCRIBED SPECIES OF THE LIPOMERINAE
la.
lb.
Pereopod VII large, similar to a walking leg
but with plumose setae on carpus and
propodus; antennula with pronounced medial
lobe on article 1 .............................................................................................
2
Pereopod VII rudimentary or absent; antennula
with obsolete medial area or small medial lobe
on article 1, medial lobe never near length of
article 2 ............................................................................................................
4
Pereonite 7 of adult extends to lateral margin
of pereon, not recessed into pleotelson ....................................................
3
Pereonite 7 recessed into pleotelson, not
extending to lateral margin of pereon ............................
Uropod small, with thick protopod having
pronounced medial projection, not leaflike;
natasome posteriorly rounded, not strongly
flexed ventrally; mandible normal, not
enlarged .............................................................................
Lionectes n. gen.
Coperonus n. gen.
Uropod large, with flattened leaflike protopod;
natasome posteriorly angular, strongly flexed
ventrally; mandible with massive molar
process and blunt incisor process ............................. Hapsidohedra n. gen.
Uropod large, flattened, never with exopod,
extending to distal tip of pleotelson; pereopod
V normal with short merus and distinct
dactylus (Lipomera Tattersall, 1905) .......................................................
5
Uropod tiny, sometimes with rudimentary
exopod, never reaching distal tip of pleotelson;
pereopod V with elongate merus and
rudimentary dactylus (Mimocopelates n.gen.) .......................................
7
Wilson: Revision of the Lipomerinae
5a.
Uropod narrow, sometimes with distinct suture
between ramus and protopod ................. Lipomera (Tetracope) n. subgen.
5b.
Uropod broad, leaflike, never with distinct
suture between ramus and protopod .......................................................
6a.
.
6b.
6
Rudimentary pereopod VII present; cuticle of
body surfaces not heavily calcified, having
smooth anterior margins without denticles;
cephalon not enlarged, same width as
pereonite 1 ................................................................
Lipomera (Lipomera)
Pereopod VII completely absent; cuticle of
body surfaces indurate, often with denticles on
anterior margins; cephalon enlarged, broader
than pereonite 1 ............................... Lipomera (Paralipomera)n. subgen.
7a.
Cephalon near width of or narrower than
pereonite 1; mandibular molar process normal,
not massive and blunt; cephalic frontal arch
protruding anteriorly in lateral view; stylet of
male pleopod I1 normal sized, approximately
half length of protopod; musculature of
pleopod I1 exopod extending to proximal
margin of protopod .............. Mimocopelates longipes n. sp. (species group)
7b.
Cephalon enlarged, distinctly wider than
pereonite 1; mandibular molar process massive
and blunt; cephalic frontal arch flattened into
frons, not protruding anteriorly; stylet of male
pleopod 11 small, less than third length of
protopod; musculature of pleopod I1 exopod
not extending to proximal margin of protopod
.................................
Mimocopelates archibraziliensis n. sp. (species group)
26
Bulletin, Scripps Institution of Oceanography
DESCRIPTIONS OF THE GENERA AND SPECIES OF THE LIPOMERINAE
COPERONUS New Genus
(Figures 4-7)
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.
Rostrum absent, vertex slightly convex in dorsal view. Frontal arch protruding
anteriorly, with raised flattened area adjacent to clypeal attachment; frontal arch
angular in anterior view. Clypeus medial section triangular in anterior view;
dorsal apex higher than articulation with frons, slightly lower than apex of
flattened area on frons. Labrum anteriorly flattened, height half that of cephalon.
Body deepest and widest at pereonite 5. Natasome compact; pereonites 5-7 with
distinct articulations dorsally 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.
Antenna1 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 comer of mandibular body; palp slightly shorter 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 I1 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
(Vanhoffen, 1914).
Remarks. Coperonus is the least modified genus of all the Lipomerinae.
Although its members have the short, broad head and reduced frontal area of the
Ilyarachnidae and the Lipomerinae, the pereon and pleotelson are much more
characteristic of the Eurycopidae in the posteriorly rounded, bullet-shaped
appearance. The uropods are also eurycopid-like, although somewhat reduced
Wilson: Revision of the Lipomerinae
27
and modified in their position. The only posterior feature that unequivocally
identifies Coperonus as a member of the Lipomerinae is the reduction of
pereonite 7 and its limb.
Coperonus may be distinguished from the other Lipomerinae by its
rounded natasome and relatively unmodified uropod. A large, somewhat
natatory pereopod VII is also useful for identification, clearly separating
Coperonus from Lipomera Tattersall, 1905, 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. Most of the syntypes of E.
frigida Vanhoffen, 1914 belong in Coperonus. Vanhoffen (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 Vanhoffen
(1914, his figure 122), the maxilliped is practically identical to that of the typespecies of Coperonus, and the male pleopods are similar, but not identical
(Vanhoffen, 1914, his figure 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 Vanhoffen's types and found his specimens different.
E. sp. cf. frigida Nordenstam, 1933 is definitely a member of Coperonus; the
illustrations (Nordenstam 1933, his figure 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, C. nordenstami, in honor of their
first describer (see diagnosis below).
Coperonus has a South Atlantic-Antarctic distributiqn. In addition to C.
frigidus (Vanhoffen, 1914) and C. nordenstami n. sp. found off East Antarctica
and South Georgia Island, respectively, three species, one of which is C. comptus
n. sp., have been found in the Weddell Sea and Palmer Peninsula area, and three
species were collected during Woods Hole Oceanographic Institution expeditions
off Argentina and Brazil.
Bulletin, Scripps Institution of Oceanography
Coperonus comptus new species
(Figures 4-7)
Holotype. Copulatory male, bl 2.6 mm, ambulatory pereopods and antennae
missing, USNM 227052.
Paratypes. Preparatory female, bl 2.8 mm, USNM 227053. Preparatory female,
copulatory male, ZMUC. Preparatory female, copulatory male, MNHN Is.1813.
Brooding female, copulatory male, BMNH 1985:417. 89 individuals, some
dissected for description, SIO.
Type-Locality. WHOI 236, 36O27.0'-28.1'S, 53O31.0'-32.3'W, 497-518 m,
collected 11 March 1971 during R/V Atlantis cruise number 60.
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 "elegant" in Latin.
Diagnosis. Apex of cephalon only slightly convex, neither linear nor strongly
convex. Pleotelson posterior margin in dorsal view smoothly curving. or
heart-shaped. Male antennular article 3 shorter than article 2. 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. 4A): Natasome with tiny setae on dorsal and lateral surfaces;
other dorsal surfaces with only scattered fine setae.
Cephalon (Fig. 4C-F): Dorsal length 0.31 width, length 0.42 height. Ventral
margin at posterior articulation of mandible with distinct indentation or notch.
Antennula (Fig. 5A-B): In males, length 0.35-0.36 (2 inds) body length; in
females, 0.23-0.26 (2 inds), Male antennula with 14 articles and approximately 6
aesthetascs distally; female 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 female;
medial lobe of 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 females, length 0.7 medial-lobe length in males.
Article 3 length 0.61 article 2 length in male, 0.71 (2 inds) in females.
Mandible (Fig. 5C-I): Normally developed. Both mandibles with 3 distinct cusps
on incisor processes. Lacinia mobilis reaching to tip of incisor process, with 4
cusps. Left spine row with 7 members. Molar process distal end with low
circumgnathal denticles, lacking large pointed cusp on ventral margin; posterior
Wilson:Revision of the Lipomerinae
Figure 5. Coperonus comptus n. gen., n. sp. A, right anterior section of cephalon showing
antennula and basal articles of antenna, holotype male. B-N, paratype brooding female, b12.8 mm.
B, right antennula. C-F, H-I, left mandible. C, dorsal view. D, distal section of palp. E, incisor
process, lacinia mobilis and spine row, ventral view. F, incisor process and lacinia mobilis, plan
view. G, incisor process, right mandible, plan view. H-I, molar process, anterior and posterior
views. J, right maxillula. K, right maxilla. L, paragnaths. M-N, right maxilliped, enlargement of
endite and whole limb, respectively.
30
Bulletin, Scripps Institution of Oceanography
margin with 3 flattened setulate setae; triturating surface with approximately 4
sensory pores. Condyle length 0.27 mandibular body length. Palp second article
length 0.49 mandibular body length.
Maxillula (Fig. 5J): Normally developed. Inner endite width 0.74 outer endite
width.
Maxilla (Fig. 5K): Normally developed. Outer lobes shorter than inner lobe.
Maxilliped (Fig. 5M-N): Basis with 4 receptaculi and 4 fan setae distally, medial
fan seta more robust, with fewer and broader branches than 3 lateral fan setae.
Endite length 0.53 total basis length. Palp 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. 4G, 6C): Bases I-IV length-body length ratios in male
holotype 0.22, 0.24, 0.23, 0.26; all similarly robust. Bases V-VII in brooding
female shorter than bases I-IV; length-body length ratios 0.1 1,O. 18,O.19.
Pereopod I (Fig. 5A-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. 6D-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; widths of carpus and propodus decrease posteriorly. Pereopod V-VII
length-body length ratios 0.70, 0.66, 0.60. Carpi V-VII length-width ratios 1.1,
1.3, 3.5. Propodi V-VII length-width ratios 1.6, 2.5, 5.6. Dactylus V tiny, with
no distal claw (or unguis); dactyli VI-VII much longer, with claw.
Male Pleopod I (Fig. 7A-B). Pleopod widest proximally, abruptly narrowing
midlength. 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 I1 (Fig. 7C): Protopod broad proximally, narrowing to small
rounded lobe distal to exopod; length 1.5 width. Small plumose setae on
distolateral margin of protopod. Stylet short, half length of protopod; sperm duct
opening at stylet midpoint. Exopod bare, without tuft of fine setae.
Wilson: Revision of the Lipomerinae
Figure 6. Coperonus comptus n. gen., n. sp. A, right pereopod I, male from WHOI 239,
b12.7 mm. B, D-F, pereopods, brooding female from WHOI 239, b13.0 mm. B, right pereopod I.
C, bases of pereopods I-IV, paratype male, b12.9 mm. D-F, natatory pereopods V-VII to same
scale, with enlargements of claws of dactyli VI-VII.
32
Bulletin, Scripps Institution of Oceanography
Female Pleopod 11 (Fig. 7G-I): Keel deep, sharply defined from lateral fields.
Dorsal surface with scattered setae; distolateral margins with small plumose
setae. Length 0.81 width; depth 0.47 length. Apex anterior to length midpoint,
lacking large seta.
Pleopod I11 (Fig. 7D): Exopod extending to distal tip of endopod, with 2 long
plumose setae, and 1 simple seta on distal tip.
Uropod (Fig. 7J): Protopod medial length 0.61 distal width. Exopod 0.69
endopod length. Endopod 0.76 medial length of protopod. Distal margin of
protopod with group of unequally bifid setae on medial lobe, and few setae
laterally.
Remarks. Coperonus has 3 described species and 5 undescribed species known
to me. C. 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.
Coperonus nordenstami new species
Synonym. Eurycope sp. cf. frigida Nordenstam, 1933.
Syntypes. Two small damaged females.
Type-Locality. Swedish Antarctic Expedition station 34. South Georgia Island,
off the mouth of Cumberland Bay, 54"l l'S, 36"18'W, 252-310 m, 5 June 1902.
Sediment gray clay with a few stones.
General Distribution. South Georgia Island. Known only from type locality.
Derivation of Name. This species is named for h e Nordenstam, the first to
report it.
Diagnosis. Apex of cephalon linear. Pleotelson posterior margin in dorsal view
appearing as rounded "V". Maxillipedal epipod distal tip rounded. Pereopod VI
only slightly shorter than pereopod V.
Remarks. The above diagnosis is somewhat limited because males are unknown.
The females differ from C. comptus in the form of the pleotelson, the cephalon,
and the maxillipedal epipod (Nordenstam 1933, his figure 78).
Wilson:Revision of the Lipomerinae
Figure 7. Coperonus comptus n. gen., n. sp. A-C, paratype male, b12.9 mm. D-J, paratype
brooding female, b12.8 mm. 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 11, with enlargement of stylet; fringing setae on distolateral margin are plumose. D-F, left
pleopods 111-V. G-I, female pleopod 11, ventral, lateral, and posterior views, respectively. J, right
uropod.
Bulletin, Scripps Institution of Oceanography
HAPSIDOHEDRA New Genus
(Figures 8-13)
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 cephalon. 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. Pleotelson subtriangular,
widest at anterior margin. Antennular first article broad, with distinct medial and
lateral lobes; medial lobe rounded, lateral lobe dorsoventrally flattened; as few as
2 flagellar articles in adult female. Antenna article 3 without distinct scale.
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 sclerotized, extending from 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 body. Pereopodal bases lengths heterogeneous: bases I1 and I11
subequal and shortest, bases IV and VI subequal and longest, bases I, V, and VII
intermediate in length. Pereopod V and VI natatory, with broad carpi and
propodi. 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, also thin. Pleopod I1 of female with slit dividing
distal tip into halves. Uropod with broad, flattened, oval protopod and 1 short
rarnus. Uropods inserting subterminally and ventrally, covering anus with
protopods.
Derivation of Name. Hapsidohedra (Greek, feminine) means "vaulted rump,"
referring to a high, arched natasome.
Composition. Hapsidohedra ochlera n. sp.; H. aspidophora (Wolff, 1962).
Remarks. Hapsidohedra is the most ilyarachnid-like of the Lipomerinae. The
broad, dorsally tubular and robust cephalon, the triangular natasome tipped with
a leaflike uniramous uropod, and a non-natatory pereopod VII are all seen in the
Ilyarachnidae. Indeed, Wolff (1962) placed the species aspidophora in
Ilyarachna, apparently overlooking characters that conflicted with his diagnosis
of the Ilyarachnidae: a large, rounded, nonsetiferous mandibular molar; elongate
Wilson:Revision of the Lipornerinae
Figure 8. Hapsidohedra ochlera n. gen., n. sp. A-B, holotype preparatory female, lateral and
dorsal views, scale bar 1.0 mm. C, paratype male, lateral view, same scale as female. D, paatype
male, enlargement of left lateral margins of pereonites 1-4 and pereopodal bases, showing relative
sizes of bases. E, pleotelson, holotype female. F, natasome, lateral oblique view, showing form of
ventral surface and relative sizes of bases V-VII, paratype female, bl 1.7 mm.
36
Bulletin, Scripps Institution of Oceanography
bases of pereopods 111-IV; and a bilobate, thick antennular article 1. This species
resembles the reasonably well-defined and specialized Ilyarachnidae, but lacks
this family's defining features. If this genus were the only known lipomerine, the
current definition of the Ilyarachnidae would be in serious doubt. 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 its resemblance.
Hapsidohedra shares several important characters with the other
Lipomerinae. These characters also distinguish the genus from ilyarachnids.
The molar process is not reduced, but is enlarged (taken to an extreme in this
genus). The bases of pereopods 111-IV are similar in length to basis 11.
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. All
lipomerines have nearly identical pleopods 111 and IV, and Hapsidohedra is no
exception.
The frons of Hapsidohedra is distinctive, but of the same general form
found in all the Lipomerinae: the frontal area is reduced, with a disappearance of
the cephalic arch and the frontal area above it. As in most lipomerines, the
anterodorsal margin of the cephalon has become heavier, 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 the phylogeny section.
Other characters help separate Hapsidohedra from the other Lipomerinae.
The leaflike uropod is most useful for separating it 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 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 2 described species at present: H. ochlera n. sp.
from bathyal waters of the Caribbean Sea off northern South America, and H.
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 its wide occurrences in the Atlantic and Pacific
oceans.
Wilson: Revision of the Lipomerinae
Hapsidohedra ochlera new species
(Figures 8- 12)
Holotype. Preparatory female, bl 2.5 mm, all pereopods except left seventh
pereopod missing, USNM 227054.
Paratypes. Preparatory female, bl 2.3 mm; brooding female, b12.2 mm; male, bl
1.7 mm: USNM 227055. Brooding female, b12.3 mm; male, bl 1.6 mm: ZMUC.
Brooding female, bl 2.3 mm; male, bl 1.6 mm: MNHNIs. 1814. Brooding
female, copulatory male, BMNH 1985:418. 56 individuals, some dissected for
description, SIO.
Type-Locality. WHOI 295, 8"04.2'N, 54"21.3'W, 1000-1022 m, collected off
Surinam during R/V Knorr cruise 25,28 February 1972.
Other Material. All at SIO: WHOI 293, 5 ind; LCLlC4, 5 ind; LGL2C2, 1 ind;
LGL2C4, 1 ind; LGL3C3, 1 ind; LGL3C7, 2 ind; LGL3C9, 1 ind; LGL4E2, 1
ind; LGL5WC6,3 ind; LGL5WC11, 1 ind.
General Distribution. Off Surinam, South America, 1000-1518 m, and in the
Gulf of Mexico off Louisiana, 554- 1390 m.
Derivation of Name. Ochlera (Greek) 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 I1 terminating abruptly anterior to distal tip, with recurved or
quadrate posterior margin in lateral view and with posteriorly directed denticles
on ventral margin.
Description. Body Characters (Fig. 8A-C,E): Adult body length 1.7-2.5 mm,
length (measured along curving body axis) 2.8 width in holotype female.
Pleotelson ventral plan view length 1.O- 1.1 width.
Body Setation (Fig. 8A,C,E-F): Cephalon with single large simple seta. Dorsal
surface of ambulatory pereonites with sparse row of simple setae near anterior
margins. Anterior margin of pereonite 5 with row of simple setae. Ventrolateral
margin of pleotelson with thick row of plumose setae.
Cephalon (Fig. 9A-D): Dorsal length 0.42 width, length 0.49 height.
Antennula (Fig. 10A-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. Female antennula with 6 articles and only 1 aesthetasc.
Article 1 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. Second article 0.62 medial length of article
1 in male, 0.76 in female.
Bulletin, Scripps Institution of Oceanography
Figure 9. Hapsidohedra ochlera n. gen., n. sp. 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. E-I, left mandible. E-F, dorsal and medial views. G , incisor
process, lacinia mobilis, and spine row, ventral view. H, incisor process and lacinia mobilis, plan
view. I, molar process, posteromedial view. J, incisor process, right mandible.
Wilson:Revision of the Lipomerinae
Figure 10. Hapsidohedra ochlera n. gen., n. sp. A-B, left antennula, dorsal and lateral views,
paratype male, b12.0 rnm. C, left antennula, paratype preparatory female, b12.0 mm. DG, paratype brooding female cephalon fragment. D, paragnaths. E, left maxillula. F, left maxilla.
G, right maxilliped with enlargement of endite distal tip.
40
Bulletin, Scripps Institution of Oceanography
Mandible (Fig. 9E-J): Left incisor process with 4 cusps, with gap between dorsal
cusp and 3 ventral cusps. Right incisor with single large cusp, and low cusps
dorsally and ventrally. Lacinia mobilis flattened, with 4 teeth. Left spine row
with approximately 5 simple members, distinctly shorter than lacinia mobilis;
right spine row with 2 members. Molar process with 3 closely-clumped setulate
setae. Condyle length 0.54 mandibular body length. Palp second article length
0.43 mandibular body length.
Maxillula (Fig. 10E): Normally developed. Inner endite 0.64 width of outer
endite.
Maxilla (Fig. 10F): Normally developed. Outer lobes distinctly shorter than
inner lobe.
Maxilliped (Fig. 10G): Coxal plate large, nearly as long as width of epipod.
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. Palp article 3
lateral length 0.29 medial length. Epipod outline bean-shaped, with rounded
lateral and distal margins; length 1.5 width; distal margin with single simple seta.
Pereopodal Bases (Fig. 8D,F; 11A-D): In female, bases I-VII length/body length
ratios 0.19, 0.16, 0.17, 0.23, 0.19,0.23, 0.20. In male, ratios for bases I-IV 0.18,
O.17,O. l7,0.23. Male bases III-IV more robust than in female.
Pereopod I (Fig. 11A): Total length 0.77 body length. Carpus length subequal to
basis length. Carpus and propodus thin, paucisetose.
Natatory Pereopods V-VI (Fig. 11B-C): Total lengths 0.69, 0.71 body length.
Ischia lengths 0.75, 0.60 bases lengths. Carpi lengthlwidth ratios 1.4, 1.4.
Propodi lengthlwidth ratios 2.0, 2.2. Dactyli short, curved, thin, lengths 0.47,
0.50 propodi lengths.
Pereopod VII (Fig. 1ID): Total length 0.65 body length. Basis length 0.27 total
length. Carpus and propodus narrow, with fewer setae on margins than on
anterior natatatory limbs; lengthlwidth ratios 5.7, 4.7. Dactylus long, thin,
curved, length 1.2 propodus length.
Male Pleopod I (Fig. 12B): 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. Inner and outer lobes continuous. Distal tip with
setae dorsally, ventrally, and more proximally along midline. Setae thick and
tubular proximally, narrowing abruptly at midlength, and thin, whiplike distally.
Remainder of ventral surface without setae.
Male Pleopod I1 (Fig. 12C): 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. Endopod
inserting 0.34 protopod length from distal tip. Stylet not extending to distal tip
of protopod, with short sperm duct, length 0.46 protopod length.
Wilson:Revision of the Lipornerinae
41
Female Pleopod I1 (Fig. 12A): Pleopod narrow, widest midlength. Length 1.9
width. Keel thin, deep, with denticles along ventral margin. Fused pleopod pair
depth 0.33 length. 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 11. Hapsidohedra ochlera n. gen., n. sp. A, left pereopod I, paratype preparatory female,
bl 1.8 mm. B-C, right natatory pereopods V-VI, paratype male, b12.0. D, left pereopod VII,
paratype preparatory female, b12.0 mm. E, right uropod, in situ, holotype female.
42
Bulletin, Scripps Institution of Oceanography
Pleopod I11 (Fig. 12D): Exopod longer than endopod, distally rounded, with long,
thin, simple setae on lateral margin, shorter, thin, simple setae on medial margin,
and 2 long plumose setae having thick simple seta between them. Endopod with
3 long plumose setae. All plumose setae longer than exopod.
Pleopod IV (Fig. 12E): Exopod short, rounded, approximately half length of
pleopod length; single long plumose seta on distal tip.
Figure 12. Hapsidohedra ochlera n. gen., n. sp. A, female pleopod 11, ventral and lateral views,
paratype preparatory female, b12.0 mm. B-F, pleopods, paratype male, b12.0 mm. B, pleopod I,
with enlargement of distal tip. C, left pleopod 11, with enlargement of stylet. D, right pleopod 111.
E-F, left pleopods IV-V.
Wilson:Revision of the Lipomerinae
43
Uropod (Fig. 11E): 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 distinguished by a female
pleopod I1 keel 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 also useful.
This species has been found in the shallow bathyal benthos of the Gulf of
Mexico and the southern Caribbean Sea. It is not known, however, whether H.
ochlera is continuously distributed, or whether it comprises disjunct populations
interrupted by barriers such as the Yucatan Peninsula.
Hapsidohedra aspidophora (Wolff, 1962)
(Figure 13)
Synonym. Ilyarachna aspidophora Wolff, 1962, pp. 106-108.
Holotype. Brooding female with about 20 embryos in marsupium, bl 3.2 mrn,
body width 1.4 mm, ZMUC.
Type-Locality. R/V Galathea station 639, off East New Zealand, 37"31'S,
177"08'E, 213 m, bottom temperature about 14.7"C (Bruun 1959).
Distribution. Known only from type locality.
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 I1 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 differs in the form of the female pleopod I1 and the
antennula. The mandibular characters, although less useful for sorting purposes,
may be useful for distinguishing H. aspidophora from H. ochlera. The male of
H. aspidophora is unknown.
Hapsidohedra aspidophora is known from surprisingly shallow (213 m)
and warm (14°C) water off East New Zealand. The full range of this species and
its preferred hydrographic regime will be of considerable biogeographic interest.
H. 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).
Bulletin, Scripps Institution of Oceanography
Figure 13. Hapsidohedra aspidophora (Wolff, 1962). A-B, dorsal and lateral views of holotype,
after Wolff (1962), scale bar = 1.0 mm.
Wilson:Revision of the Lipornerinae
LIONECTES New Genus
(Figures 14-17)
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.
Rostrum absent, vertex slightly convex in dorsal view. 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.
Antenna1 scale absent. Mandible somewhat modified: spine 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 comer of mandibular body; ventromedial region of
mandibular body reduced, not protruding; palp not reduced, with robust
segments. Lengths of pereopodal bases heterogeneous: bases I, 11, 111, 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. Female pleopod I1 distal tip
entire, lacking slit. 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. Lionectes (Greek, masculine) means "smooth swimmer,"
referring to the very smooth dorsal surface of members of this genus.
Remarks. Lionectes is a member of the lipomerine group that has ambulatory
seventh pereopods. In addition to Lionectes, the group includes Coperonus and
46
Bulletin, Scripps Institution of Oceanography
Hapsidohedra. Because this group has functional seventh pereopods, it is
distinct from the genera Lipomera and Mimocopelates, which lack seventh
pereopods (or at least functional ones). Although these three genera resemble
each other in general form of the cephalon and the natasome, each has
specializations, or lack thereof, that make them distinct. Lionectes is identified
by a smooth, almost seedlike habitus in dorsal view, terminally placed uropods
that protrude from a posterior opening in the pleotelson, a dorsoventrally
flattened head, and a distal section of the pereon that is recessed into pockets in
the pleotelson. Details of the mandible and the frons are also useful for
identifying this genus.
The composition of Lionectes is currently complicated by Eurycope frigida
Vanhoffen, 1914, described from 10 specimens collected at Gauss Station
(8/11/1903) in fairly shallow water off eastern Antarctica. Vanhoffen's
(1914590) illustrations 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 "juvenile" may be a member of
Lionectes. The adult is much larger than the supposed juvenile - 2.5 mm versus
1 mm - and the juvenile is not a manca. In addition, the "juvenile" has a number
of 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 flagellar articles; and the uropods project into
dorsal view from the tip of the pleotelson. Unfortunately, Vanhoffen (1914) did
not describe the uropods. The "juvenile" has one characteristic, in addition to the
above differences with the "adult," that makes its 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 Vanhoffen's drawing (his
figure 123A) to protrude from above the pleopod 11, indicating that the posterior
part of the pereon is recessed into the pleotelson - a diagnostic character of
Lionectes. The larger individuals (Vanhoffen's figures 122A, 123C-D) are
assigned to Coperonus because 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
fully.
The distribution of Lionectes is limited to Antarctic seas, with L.
humicephalotus from the South Shetland Islands and the Weddell Sea, and L. sp.
incertae sedis from eastern Antarctica. Known members of this genus are very
small, so the restricted distribution may partially result from sampling artifacts.
Lionectes has not been found in the relatively carefully sampled Atlantic Ocean,
giving evidence that this genus is not cosmopolitan. Interestingly, 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.
Wilson: Revision of the Lipomerinae
Lionectes humicephalotus new species
(Figures 14-17)
Holotype. Brooding female, bl 1.2 mm, all limbs on right side except pereopod I
intact, USNM 227056.
Paratypes. Three brooding females, all bl 1.2 mm, 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°18'S, 58"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, IODal7; 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. 14A-B): Adult
body length 1.1-1.4 (4 inds) mm, length 1.9-2.0 (4 inds) width.
Body setation (Fig. 14B): Natasome with approximately 5 setae on each
ventrolateral margin; other dorsal surfaces with scattered fine setae.
Cephalon (Fig. 14C-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. 14C): 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. Article 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. 14A): 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. 15A-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. Spine row
reduced, with 3 members. 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 surface without evident
sensory pores. Condyle length 0.35 (2 inds) mandibular body length. Palp
Bulletin, Scripps Institution of Oceanography
Figure 14. Lionectes humicephalotus n. gen., n. sp. A-C, holotype brooding female. A, lateral
view, with enlargement of uropod. B, dorsal view, scale bar 1.0 mm. C, cephalon dorsal view.
D-F, cephalon, paratype brooding female, bl 1.2 mm, lateral, frontal oblique and anterior views
respectively.
Wilson:Revision of the Lipomerinae
Figure 15. Lionectes humicephalotus n. gen., n. sp., paratype brooding female, 1.2 mm. A, CG, left mandible. A, dorsal view. B, incisor process, right mandible. C, incisor process and lacinia
mobilis, plan view. D, molar process, posterior view. E, posterior view of whole mandible. F,
palp, lateral view, setae omitted. G , whole mandible, ventral view. H, left maxillula. I, right
maxilla. J, right maxilliped.
50
Bulletin, Scripps Institution of Oceanography
second article length 0.36-0.38 (2 inds) mandibular body length; distal article
robust, strongly curled.
Maxillula (Fig. 15H): Normally developed. Inner endite short and rounded,
lacking large apical seta, but with several smaller setae, width 0.61 outer endite
width.
Maxilla (Fig. 151): Normally developed. Outer lobes approximately same length
as inner lobe.
Maxilliped (Fig. 15J): Basis with 2 receptaculi and 3 fan setae distally. Endite
length 0.52 total basis length. Palp article 2 width 1.9 endite width, lateral length
2.0 medial length. Palp article 3 lateral length 0.34 medial length. Epipod oval,
lateral edge scalloped; length 0.88 basis length; length 1.5 width. Coxa elongate,
subequal to basal section of basis.
Ambulatory Pereopods (Fig. 14A, 16A): Pereopods I-IV thin, lightly setose;
length-body length ratios 0.61, 0.92, 1.O, 1.2. Bases I-IV length-body length
ratios 0.17,0.15,0.17,0.21.
Natatory Pereopods (Fig. 16C-E): Natapods heterogeneous in form: pereopod V
with very broad carpus and propodus, many natatory setae, and rudimentary
dactylus; pereopod VI with narrower carpus and propodus, many natatory setae,
and long curved dactylus; pereopod VII resembling walking leg with narrow
distal segments, approximately 4 natatory setae on ventral margin of carpus only,
propodus longer than carpus. Pereopods V-VII increasing in length but
becoming narrower posteriorly; length-body length ratios 0.74, 0.79,0.83. Bases
V-VII also increasing in length posteriorly; length-body length ratios 0.17, 0.21,
0.23. Carpi V-VII length-width ratios 1.O, 1.4, 3.7. Propodi V-VII length-width
ratios 1.5, 2.5, 6.6; propodi V-VII length carpus length ratios 0.90, 0.84, 1.5.
Dactyli VI-VII long, curved; length-propodus length ratios 0.90, 0.89. Dactylus
V rudimentary.
Male Pleopods I and 11: unknown.
Female Pleopod I1 (Fig. 17A-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 I11 (Fig. 17D): 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. 14A, 17G): Protopod length 1.4 width; length 0.08 body length.
Exopod 0.54 endopod length. Endopod 0.68 protopod length. Distal margin of
protopod with approximately 6 whip setae.
Remarks. Lionectes humicephalotus is currently known only from females; 4
brooding females were collected at the type locality off King George Island, and
Wilson:Revision of the Lipomerinae
Figure 16. Lionectes humicephalotus n. gen., n. sp., 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. C, right pereopod V with enlargement of dactylus. D-E, left pereopods VIVII.
52
Bulletin, Scripps Institution of Oceanography
the other two localities yielded only damaged females. L. sp. incertae sedis
(Vanhoffen, 1914) is also known from a single female. There are differences
between the illustrations of L. sp. incertae sedis and L. humicephalotus 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
because Vanhoffen's specimen was not brooding. A more detailed
characterization of Lionectes must await the capture of males.
Figure 17. Lionectes hurnicephalotus n. gen., n. sp., paratype brooding female, bl 1.2. A, ventral
view of pleotelson. B-C, pleopod 11, lateral and posterior views. D-F, left pleopods 111-V. G , left
uropod, lateral view.
Wilson:Revision of the Lipomerinae
Genus LIPOMERA Tattersall, 1905
(Figures 18-27)
Type-Species. Lipomera lamellata Tattersall, 1905.
Generic 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. Rostrum nearly
absknt, vertex smoothly convex in dorsal view. Frons broadly rounded, almost
flat, lacking frontal arch, with distinct separation between antennulae. Clypeus
arched, narrow strip, medial part triangular in frontal view, apex articulating
directly to frons. Labrum high, height greater than half cephalon height. 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.
Hindgut anterior to pleotelson with distinct bend or coil. 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 comer of mandibular body. Pereopodal bases 1-111
and VI subequal, 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 subequal. Female pleopod I1 tip with short
fused slit. Uropod lacking rami; protopod flattened, leaflike.
Derivation of Name. In the name Lipomera, Tattersall (1905a, 1905b) seems to
be referring to the lack of a well-developed seventh pereonite in this genus by
combining lipo-, a prefix meaning "to be lacking," with mera, a latinized form of
the feminine Greek word meris which means "a part."
Remarks. Tattersall (1905a) made this genus the type of his new family
Lipomeridae, whereas the same author (1905b), in writing the full description of
Lipomera, placed it in the Munnopsidae, which then included the current family
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 second paper may possibly have come out late
in 1905, making some authors believe it was published in 1906. If Lipomera is
placed in the same family as Eurycope, but separate from the Munnopsidae, then
the family must be called the Lipomeridae because a family-level name was not
based on Eurycope until Hansen's (19 16) Eurycopini. Under previous
classifications, the Eurycopidae would be a junior synonym of the Lipomeridae,
even though the former name has wide acceptance. The revised classification of
54
Bulletin, Scripps Institution of Oceanography
the munnopsid taxa (see phylogeny and classification section) places the
Lipomerinae in a subfamily separate from the Eurycopinae, retaining this useful
name.
Lipomera is easily distinguished from other Lipomerinae, none of which
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 Lipornera from the new
genus Mimocopelates. Rudimentary or absent seventh pereopods distinguish
Lipomera from the new genera Coperonus, Hapsidohedra, and Lionectes.
Lipomera must be divided into three subgenera - L. (Lipomera), L.
(Tetracope), and L. (Paralipomera) - because important specializations identify
groups of species within the genus but not the genus as a whole. Members of the
subgenus Lipomera are short and broad, and have short heads, smooth dorsa
without denticles on the anterior margins, and rudimentary seventh pereopods
and pereonites. The subgenus Tetracope is similar to L. (Lipomera) in body
shape and retention of a rudimentary pereopod VII, but it 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. The subgenus
Paralipomera is similar to L. (Lipomera) in having only a modest bend in the
hindgut, pereonite 5 and pereopod V larger than pereonite 6 and pereopod VI,
and 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 pereopods or pereonites as adults.
As mentioned above, species of Lipomera have curved, strongly bent, or
coiled hindguts (Fig. 24). This is highly unusual in the Crustacea. Few other
groups are known to have coiled guts; Calman (1909) mentioned only two, a
group of Cladocera and a single genus of Cumacea. Another Janiroidean genus,
Pleurocope, also has a highly modified alimentary canal, although this latter
form is different from a strictly coiled condition (Wilson, in prep.). A curved or
coiled gut is a derived condition in this genus, because all other Lipomerinae, or
munnopsids more generally, have straight guts. In another invertebrate taxon,
the bivalve Abra profundorum, a coiled gut has been considered an adaptation to
the food-poor environment of the deep sea (Allen and Sanders 1966). The
midgut caeca q e unusually large in Lipomera, supporting this hypothesis.
Improved digestion does not necessarily explain the convoluted guts seen in
Lipomera, although alternative hypotheses are not apparent at this time.
Lipomera is currently known only from the North and South Atlantic
Ocean and the Gulf of Mexico.
Wilson: Revision of the Lipomerinae
Subgenus LIPOMERA Tattersall, 1905
(Figures 18,24B)
Diagnosis. Dorsal surface of body with thin, smooth cuticle; anterior margins of
pereonites without denticles. Cephalon not indurate. Pereonite V longer than
pereonite VI. Mandible not heavily sclerotized and strengthened. Hindgut
anterior to pleotelson curved, not coiled. Pereopod VI shorter than pereopod V.
Pereopod VII present but rudimentary.
Composition. Monotypic: Lipomera (Lipomera) lamellata Tattersall, 1905.
Lipomera (Lipomera) lamellata Tattersall, 1905
(Figure 18)
Types. Eleven syntype individuals from 60 miles West of Achill Head, Ireland,
August 1901, 199 fathoms (364 meters), 53"58N, 12'16'W. Length of adult
female reported as 1.25 rnrn. Complete description by Tattersall (1905b, pp. 3235, pl. viii, locality data on p. 75). No holotype or depository designated in
original or later description. Types cannot be found (R. Lincoln, personal
communication).
Distribution. Known only from the type-locality off the western coast of central
Ireland at a depth of 364 m.
Diagnosis. Anterior margins of dorsal segments without denticles. Cephalon
medial length approximately one-third cephalon width. Body dorsal surfaces
smooth, with few setae; anterolateral comers of pereonites and pleotelson with
long setae. Male antennula with 11-13 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 because it inhabits a depth too shallow for
many deep sea studies, and too deep for most shallow water benthic work. An
undescribed species of L. (Lipomera) occurs off Walvis Bay, Africa, at a depth of
approximately 200 m. L. (L.) lamellata differs from this other species in the
collection by 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.
Bulletin, Scripps Institution of Oceanography
Figure 18. Lipomera (Lipomera) lamellata Tattersall, 1905. A, holotype female, dorsal view.
B, uropod, ventral and lateral views. C, rudimentary pereopod VII. After Tattersall (1905b).
Wilson:Revision of the Lipomerinae
PARALIPOMERA New Subgenus
(Figures 19-22)
Diagnosis. Dorsal surface partially indurate, with denticles on anterior margins.
Cephalon indurate. Pereonite V longer than pereonite VI. Mandible heavily
sclerotized and strengthened. Hindgut anterior to pleotelson curved, not coiled.
Pereopod VI shorter than pereopod V. Pereopod VII absent. Uropod large,
leaflike, round, extending beyond distal tip of pleotelson.
Derivation of Name. Paralipomera (Greek, feminine) means "next to
Lipomera."
Composition. Lipomera (Paralipomera) knorrae n. sp. Monotypic but with at
least 3 undescribed species.
Lipomera (Paralipomera) knorrae new species
(Figures 19-22)
Holotype. Copulatory male, bl 1.2 mm, USNM 227057
Paratypes. Brooding female, bl 1.5 mm, USNM 227058. Copulatory male, bl
1.2 mm, ZMUC. Brooding female, bl 1.4 mm, MNHN Is. 1815. Ten individuals,
some dissected for description, SIO.
Type-Locality. WHO1 340, 38O14.4-17.6'N, 7O020.3-22.SYW,3264-3256 m,
collected with an epibenthic sled, 3 December 1973, R/V Knorr cruise no. 35, leg
2.
General Distribution. Known only from type-locality, Western Atlantic on the
Gay Head-Bermuda transect, 3256-3264 m.
Derivation of Name. 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 medial length approximately half cephalon
width. 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. Male pleopod I tip narrow, acutely pointed. Uropod
posterior margin convexly curved.
Description. Body Characters (Fig. 19A-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. 19D-G): Width 0.79 body width, ratio range 0.72-0.83 (8 inds).
Medial dorsal length 0.54 width; length 0.72 height. Ventral margin at posterior
articulation of mandible with distinct indentation or notch.
Bulletin, Scripps Institution of Oceanography
Figure 19. Lipomera (Paralipomera) knorrae n. subgen., n. sp. A-B, holotype male, dorsal and
lateral views, scale bar 1.0 mm. C, 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.
Wilson: Revision of the Lipomerinae
59
Antennula (Fig. 19A-B, 20A-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; 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. 20C-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. 20H): Normally developed. Inner endite width 0.41 outer endite
width.
Maxilla (Fig. 201): Normally developed. Outer lobes shorter than inner lobe.
Maxilliped (Fig. 20J): 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 fewer
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. Palp
article 3 lateral length 0.33 medial length. Epipod medial margin straight; distal
tip rounded, with single seta; length 0.62 basis length; length 1.8 width.
Ambulatory Pereopods (Fig. 21A-E): Pereopods I-IV similar, thin, without large
spinelike setae; length-body length ratios 0.64, 0.95, 0.93, 0.95. Pereopod I not
sexually dimorphic. Bases I-IV length-body length ratios 0.18, 0.18, 0.18, 0.19.
Bases 11-IV with group of broom setae on anterior midpoint.
Natatory Pereopods (Fig. 21F-G): Natapods heterogeneous in form: pereopod V
larger that pereopod VI, pereopod VII absent. Pereopod length-body length
ratios 0.66 and 0.54. Bases V-VI length-body length ratios 0.21 and 0.17; both
segments with long row of simple or whip setae. Basis V thickened distally, with
distal group of broom setae. Carpi V-VI length-width ratios 1.3 and 1.6.
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 long and curved; unguis VI similar but very short.
60
Bulletin, Scripps Institution of Oceanography
Figure 20. Lipomera (Paralipomera) knorrae n. subgen., n. sp. A, right antennula, paratype
female, bl 1.4 mm. B-J, paratype male, bl 1.5mm. B, right, antennula and antenna, basal
segments, cuticular ridges shown, lateral view. C, E-G, left mandible. C, dorsal view. D, incisor
process, right mandible, plan view. E, incisor process and lacinia mobilis, plan view. F, distal part
of mandibular body, ventral view; dotted lines show thickness of sclerotization. G, molar process,
medial view. H, left maxillula. I, left maxilla. J, maxilliped, with enlargement of distal tip, fan
seta from subdistal row shown separately.
Wilson: Revision of the Lipomerinae
Figure 21. Lipomera (Paralipomera) knorrae n. subgen., n. sp. A, right pereopod I, male
holotype, bl 1.2 mm. B-G, left pereopods I-VI, paratype male, bl 1.5 mrn, pereopod I1 with
enlargements of 2 joints and distal tip. B-E at half scale of A and G-F.
62
Bulletin, Scripps Institution of Oceanography
Male Pleopod I (Fig. 22A-B). Fused pleopod pair widest at insertion, tapering to
distal tip. Length 2.7 width; width at dorsal orifice 0.43 total width. Dorsal
orifice 0.24 total length from distal tip. 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 I1 (Fig. 22A,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 I1 (Fig. 22H-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 I11 (Fig. 22E): 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. Endopod with 3 long plumose setae.
Uropod (Fig. 22K): Protopod broad, rounded, and flattened, with dorsal fold
having two plumose setae medially. Protopod dorsal length 1.49 width; medial
length 0.12 body length. Distal margin of protopod with small group of simple
setae and broom setae.
Remarks. Lipomera (Paralipomera) knorrae can be distinguished from 3 other
undescribed species in this subgenus by the presence of spines on the anterior
margins of the cephalon and pereonites, by the shape of the pleotelson, and its
relative paucity of fine setae on the dorsal surface. This Northwestern Atlantic
species is the deepest occurring member of the genus Lipomera. Undescribed
species of L. Paralipomera are found at slope depths off Africa, Brazil, and the
southern United States (in the Gulf of Mexico).
Wilson: Revision of the Lipomerinae
63
Figure 22. Lipomera (Paralipomera) knorrae n. subgen., n. sp. A-G, K, paratype male, bl 1.5 mm.
A, ventral oblique view of natasome, showing form of ventral surface. B, pleopod I with
enlargement of distal tip. C-D, left pleopod 11, whole limb and enlargement of distal portion,
showing endopod and exopod through ventral cuticle. E-G, left pleopods 111-V. H-J, pleopods 11,
paratype female, bl 1.4 mrn: ventral, lateral, and posterior views, respectively. K, right uropod,
lateral view.
Bulletin, Scripps Institution of Oceanography
TETRACOPE New Subgenus
(Figures 23-27)
Diagnosis. Dorsal surface of body with thin, smooth cuticle; anterior margins
without denticles. Cephalon not indurate. Pereonite V shorter pereonite VI.
Mandible not heavily sclerotized and strengthened. Hindgut anterior to
pleotelson coiled, or with exaggerated bend (Fig. 24). Pereopod VI
approximately same length as pereopod V. Pereopod VII present but
rudimentary (Fig. 24A). Uropod narrow, pointed, not extending beyond distal tip
of pleotelson, with 2 segments in some species.
Composition. Lipomera (Tetracope) intestinata n. sp. Monotypic, but with at
least 3 undescribed 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.
Remarks. An 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 homologies are distinctive (see Figs.
27M, 0 , and 22K). Both L. (T.) curvintestinata n. sp. and L. (T.) sp. have a long
thin dorsal seta, a distal group of broom setae, and a pair of small curled setae on
the lateral proximal margin. In L. (T.) sp., however, the uropod is clearly divided
into two sections. Because the exopod is small or lost in most munnopsids, the
large distal section is the uropodal endopod. Also the exopod never has broom
setae on the distal tip, and the endopod does. The setal homologies may be
extended to the other members of Lipomera, L. (Paralipomera) knorrae, for
example. In this latter species the uropod is a single segment and leaflike. 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.) cuwintestinata
and the broad uropod of L. (P.) knorrae must consist of the fused segments of the
protopod and the endopod.
Lipomera (Tetracope) curvintestinata new species
(Figures 23-27)
Holotype. Copulatory male, bl 0.74 mm, only a few limbs broken off,
USNM 227059.
Paratypes. Preparatory female, bl 0.87 mm, USNM 227060. Male, brooding
female, BMNH 1985:419. Male, brooding female, MNHN Is. 1816. Male,
preparatory female, ZMUC. 44 specimens, some dissected for description, SIO.
Type-Locality. WHO1 209, 39.6-46.0', 70°49.9-49.5'W, 1501-1693 m, collected
on the Gay Head-Bermuda Transect during R/V Chain cruise no. 88,22 February
1969.
Wilson:Revision of the Lipomerinae
Figure 23. Lipomera (Tetracope) curvintestinata n. subgen., n. sp. A, C, holotype male, lateral
and dorsal views. B, D, paratype preparatory female, lateral and dorsal views. Scale bar 1.0 mm.
66
Bulletin, Scripps Institution of Oceanography
Other Material. WHOI 73,4 brooding females. WHOI 210,2 brooding females,
1 male. BAT M1-13-1-7, juvenile female. BAT S1-3-1-3, female. BAT
S2-3-2-(1-9), juvenile male.
General Distribution. Slope depths off east coast of the United States,
1500-2064 m.
Derivation of Name. Cuwintestinata 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. Hindgut anterior to pleotelson
with 1 complete coil. Female antennular article 3 length approximately 2 times
length of article 4. Adult male antennula with 14-15 articles. Pleotelson sides
almost straight, terminating with rounded point in dorsal view; dorsal surface of
pleotelson only weakly curving in lateral view. Male pleopod I tip narrow,
rounded. Keel of female pleopod I1 flattened anteriorly, appearing as straight
line in lateral view, with angular transition at anteroventral apex. Uropodal
protopod and distal rarnus fused, with no apparent suture (compare Fig. 27 M and
0).
Description. Body Characters (Fig. 23A-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.
Cephalon (Fig. 25A-D): Dorsal length 0.38 width, length 0.54 height. Ventral
margin at posterior articulation of mandible with deep fold projecting laterally.
Antennula (Fig. 26A-C): 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. 25E-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. Left spine row
with 4 members, right spine row with 5. Molar process posterodistal edge with
Wilson:Revision of the Lipomerinae
Figure 24. Hindgut form in two species of Lipomera. A, Lipomera (Tetracope) cuntintestinata n.
subgen., n. sp., paratype brooding female, b10.9 mm, view of alimentafy canal and digestive caecae
through ventral body surface. B, Lipomera (Lipomera) sp., male, b10.8 mm, WHO1 180, oblique
view through ventral cuticle showing alimentary canal and digestive caeca.
Bulletin, Scripps Institution of Oceanography
K:::
Figure 25. Lipomera (Tetracope) curvintestinata n. subgen., n. sp., paratype male, b10.74 mm. AD, cephalon, antennula and antenna removed to show frons: lateral, frontal oblique, anterior, dorsal
views. 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-G, J-N, left mandible. F, dorsal view. G, palp, lateral view.
H-I, incisor process, right mandible, ventral and plan views. J-K, incisor process, lacinia mobilis,
and spine row, ventral and plan views. L, molar process and condyle, posteromedial view.
M-N, molar process, posterior and anterior views.
Wilson:Revision of the Lipomerinae
69
Figure 26. Lipornera (Tetracope) curvintestinata n. subgen., n. sp. A, left antennula, paratype
preparatory female, b10.84. B-J, paratype male, b10.74 mm. B-C, left antennula, lateral view of
whole limb and dorsal view of proximal articles. D, paragnaths. E, left maxillula. F, left maxilla.
G , left maxilliped. H, left pereopod I. I-J, right pereopods V-VI.
70
Bulletin, Scripps Institution of Oceanography
Figure 27. Lipomera (Tetracope) curvintestinata n. subgen., n. sp. A-F, J-N, paratype male,
b10.74 mm. G-I, paratype preparatory female, b10.84 mm. A, pleotelson and pereonites 6-7,
ventral view, rudimentary pereopod VII indicated (pVII). C, pleopod II. D, pleopod 11 distal tip,
medial view. E-F, pleopod I, ventral and lateral views. G-I, female pleopod 11, posterior, lateral,
and ventral views. J-L, right pleopods 111-V. M, right uropod, lateral view. N, left uropod, ventral
view. 0,uropods, Lipomera (Tetracope) sp., brooding female, bl 1.1 mm, WHO1 119.
Wilson:Revision of the Lipornerinae
71
gnathal plate having 3 sharp denticles and 2 flattened setulate setae; triturating
surface with no visible sensory pores. Condyle longer than molar process,
distinct from posterior support ridge; length 0.31 mandibular body length. Palp
second article length 0.51 mandibular body length. Distal article not strongly
curved.
Maxillula (Fig. 26E): Normally developed. Inner endite width 0.45 outer endite
width.
Maxilla (Fig. 26F): Normally developed. Outer lobes approximately same length
as inner lobe.
Maxilliped (Fig. 26G): Basis with 2 receptaculi and 3 fan setae distally; proximal
part of basis not expanded, lateral edge broadly 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
broadly curved on medial margin, strongly curved laterally, with fringe of fine
setae distolaterally; length 0.84 basis length; length 1.4 width.
Ambulatory Pereopods (Fig. 23A, 26H): Pereopods 11-IV with sparse row of thin
setae on dorsal and ventral margins of carpus and propodus, pereopod I with few
setae; length-body length pereopods I-IV ratios 0.90, 1.18, 1.23, 1.32. Pereopod
I not sexually dimorphic. Bases I-IV length-body length ratios 0.25, 0.26, 0.28,
0.28. Bases 11-IV with few setae.
Natatory Pereopods (Fig. 261-J, 27A): Natapods V-VI similar in form, with broad
carpi and propodi; pereopod VII present only as tiny, rudimentary 2- or 3segmented appendage inserting medial to posterior edge of coxa VI. Pereopod
V-VI length-body length ratios 0.93,0.89. Bases V-VI length-body length ratios
0.26, 0.24; basis V with distal broadened area having group of broom setae.
Carpi V-VI length-width ratios 1.3, 1.5. 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. 27A,E-F). Fused pleopod pair widest just distal to rounded
proximal margin, afterwards triangular, with almost linear lateral margins and
narrow distal tip. Proximal funnel with dorsal bend, enclosing elongate penes.
Length 2.9 width; width at dorsal orifice 0.32 pleopod width. 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 I1 (Fig. 27A-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. Exopod small, rounded, with
few fine setae.
72
Bulletin, Scripps Institution of Oceanography
Female Pleopod I1 (Fig. 27G-I): Keel deep, acute in posterior view, apex near
anterior margin, sloping posteriorly and laterally to dorsally recurved 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 I11 (Fig. 275): 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. 27M-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) cuwintestinata was the first isopod species I
found with a complete coil in the hindgut. A survey of all the ilyarachnid-like
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 distinct
convolutions in their uncoiled guts (see Fig. 23B).
L. (T.) Cuwintestinata 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 nonsegmented uropod. The form of the body segments
and the antennulae may be useful indicators of species differences as well.
MZMOCOPELATES New Genus
(Figures 28-35)
Type-Species. Mimocopelates longipes new species.
Generic Diagnosis. Dorsal surface smooth, without spines. Rostrum absent.
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. Labrum anteriorly rounded. 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. Antenna1 scale absent. Mandible modified: molar process
distally convex and heavily sclerotized, with reduced or absent circumgnathal
m a t u r e ; support ridge extending 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
Wilson: Revision of the Lipomerinae
73
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 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."
Composition. Mimocopelates longipes n. sp., M. anchibraziliensis n. sp.; at least
3 undescribed species.
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 could predict that somewhere in
the deep sea a munnopsid 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 munnopsids, 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 munnopsid 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.
Mimocopelates contains two distinctive groups: one represented by M. longipes
n. sp., and the other by M. anchibraziliensis n. sp. Because these two species are
so dissimilar in cephalic size and many other characters, I once believed they
should be separate genera. The characters mentioned above, however, outweigh
these considerations, and some of the specialized features that distinguish the two
species, such as the size of the head, are known to vary within munnopsid genera.
For example, compare the cephalic and mandibular development of Eurycope
iphthima Wilson, 1981 and E. juvenalis Wilson, 1982b.
Species of the Mimocopelates longipes group are all similar, although
several characters may be useful for distinguishing them. These are the shape of
the vertex and the interantennular distance, the length of the endopod compared
to the width of the protopod, and the shape of the male pleopod I tip and the
number of setae on it.
Mimocopelates, like most deep-sea asellote genera, may be cosmopolitan:
it has been found 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 of this genus from bathyal depths off
New Zealand. The latter specimens represent an undescribed species.
Bulletin, Scripps Institution of Oceanography
Figure 28. Mimocopelates longipes n. gen., n. sp. A-B, holotype male, lateral and dorsal views,
scale bar 1.0 mm. C-D, paratype preparatory female, bl 1.9 mm. C, dorsal view. D, ventral
oblique view of natasome, showing form of ventral surface and comparative sizes of pereopodal
bases.
Wilson:Revision of the Lipomerinae
Mimocopelates longipes new species
(Figures 28-32)
Holotype. Copulatory male, bl 2.1 rnrn, distal parts of antennulae, antennae, and
pereopods I-IV broken off, USNM 227061.
Paratypes. Preparatory female, bl 2.2 mm, USNM 227062. Brooding female
and copulatory male, bl 2.2., 1.9 respectively, ZMUC. Brooding female, bl 2.2
mm, MNHN Is. 1817. Preparatory female, BMNH 1985:420. 18 individuals,
some fragmentary or dissected for description, SIO.
Type-Locality. WHOI 321, 50°12.3'N, 13"35.8'W, 2868-2890 m, collected on
20 August 1972 during R/V Chain cruise no. 106.
Other Material. All specimens at 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 DS 1 3 , l ind.; INCAL OS04,l ind.
General Distribution. Eastern and western North Atlantic from 50" 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 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
distal tip 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. 28A-C): Adult body length 1.9-2.2 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. 28A-C): Natasome with many fine setae on dorsal surfaces;
ambulosome and cephalon with scattered fine setae.
Cephalon (Fig. 29A-C): Dorsal length 0.43 width, height 1.3 width.
Antennula (Fig. 30E-F): Flagellum and more proximal segments broken in all
specimens examined. Male antennula more robust and possibly longer than
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Figure 29. Mimocopelates longipes n. gen., n. sp., paratype female, bl 1.9 mm. A-C, cephalon,
frontal oblique, anterior, and lateral views, antemula and antenna removed to show frons. DI, K, left mandible. D, dorsal view. E, palp, distal segment. F-G, mandibular body and distal tip,
ventral view. H, molar process and condyle, posterior view. I, incisor process and lacinia mobilis,
plan view. J, incisor process, right mandible, plan view. K, molar process, anterior view.
Wilson:Revision of the Lipomerinae
77
female antennula; 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 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. 29D-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. Both spine rows with 5 members each. 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. 30B): Normally developed. Inner endite width 0.64 outer endite
width. Distal tip of inner lobe with several very fine, equally bifid setae.
Maxilla (Fig. 30C): Normally developed. Outer lobe length subequal to inner
lobe. Central lobe shorter than inner lobe.
Maxilliped (Fig. 30D): 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. 31A-B): Bases I-IV subequal, lengths 0.31 body
length. In male, pereopod I length 1.2 body length; ischium length 0.63 basis
length.
Natatory Pereopods (Fig. 31C-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. 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. Pereopod V
merus length 0.73 ischium length. Carpi V-VI length-width ratios 1.1 and 1.7.
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Figure 30. Mimocopelates longipes n. gen., n. sp. A-E, H, paratype preparatory female, bl 1.9
mm. A, paragnaths. B, left maxillula, with enlargement of distal tip of inner endite. C, right
maxilla. D, left maxilliped with enlargement of endite distal tip. E, proximal articles of right
antennula. F, proximal articles of right antennula, paratype male, b12.1 mm. G , right uropod,
proximal parts seen through cuticle, holotype male, b12.1 mm. H, left uropod, medial view.
Wilson:Revision of the Lipomerinae
79
Propodi V-VI length-width ratios 1.9 and 2.9. Dactyli V-VI length-propodus
length ratios 0.14 and 0.63.
Male Pleopod I (Fig. 32A-C). 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. Length 3.1 width; width at dorsal
orifice 0.56 pleopod width. 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 comers. 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 I1 (Fig. 32D-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
of fine setae on dorsal side.
Female Pleopod I1 (Fig. 321-L): Opercular pleopod pair triangular in ventral
view, with tiny fused groove in distal tip. Keel broad, rounded, lateral fields not
distinct from sides of keel; row of fine setae along keel. Lateral margins curling
dorsally, distal part with simple setae grading into plumose setae. Length 1.3
width; depth 0.37 length. Apex ventral to insertion, but not extending anteriorly;
apex lacking large seta.
Pleopod I11 (Fig. 32F): 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. 30G-H): Protopod broader than long, medial length 0.74 distal
width; medial length 0.03 body length. Exopod tiny, with 2 simple setae.
Endopod 1.3 medial length of protopod. Distal margin of protopod with 2 simple
setae on posteromedial comer.
Remarks. Mimocopelates longipes may be distinguished from 3 other
undescribed species of this genus by the following characters. The cephalic
vertex is unmarked by a cuticular line, and the cephalic dorsal surface curves
directly into the frons. The antennulae are set fairly far apart compared to one
species where the interantennular distance is small. The uropodal endopods are
longer and narrower than those seen in other similar species. Many characters
distinguish M. longipes from the much larger M. anchibraziliensis. A less
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Bulletin, Scripps Institution of Oceanography
massive head that is recessed into the first pereonite, and a large biramous uropod
are probably the easiest characters by which to identify M. longipes.
The setal groups on the tip of male pleopod I (Fig. 32A) are unique, and are
exactly the same for all males of M. longipes from the northeastern Atlantic. The
males of this species from the Western Atlantic may have a large medial fatbased seta instead of a small one. Only fully mature males may be used for these
male pleopod characters because the preceding juvenile male instar has a flat,
almost featureless pleopod I. Maturity may be judged in this species (as in most
Janiroidea) by a pleopod I1 stylet sperm tube which is open at both ends.
Juvenile males generally have either closed or absent sperm tubes.
M . longipes has a broad distribution, both vertically and geographically,
compared to distributions of other eurycopids from the north Atlantic (Wilson
1983a; 1982b). This species is found in some of the same localities as the E.
complanata complex (Wilson 1982b), leading one to wonder whether a cryptic
species complex is present. It is replaced, however, at a central North Atlantic
station ('WHO1 334) by another undescribed species, suggesting that it is limited
to proximity of the continental margins.
Figure 31. Mimocopelates longipes n. gen., n. sp. A, (31-E, holotype male, b12.1 mm. A, bases of
right pereopods I-IV, in situ. B, left pereopod I, paratype male, b12.1 mm, with enlargement of
dactylar claw. C, right pereopod V, in situ, with enlargement of dactylus. D, right pereopod VI, in
situ. E, pereopod VI enlargement of dactylar tip. Illustrations all to same scale.
Wilson:Revision of the Lipomerinae
Figure 32. Mimocopelates longipes n. gen., n. sp. A-E, pleopods I-11, paratype male, b12.1 mm.
F-L, pleopods II-V, paratype preparatory female, 1.9 mm. A-C, pleopod I, ventral view with
enlargement of distal tip, lateral view, and dorsal view of distal tip. D-E, left pleopod 11, ventral
view and dorsal view of distal tip with enlargement of stylet tip. F-H, right pleopods 111-V. I-L,
pleopod 11: ventral, lateral, posterior, and dorsal views, respectively.
Bulletin, Scripps Institution of Oceanography
Mimocopelates anchibraziliensis new species
(Figures 33-35)
Holotype. Preparatory female, b14.2 mm, distal parts of antennae, and pereopods
I-IV broken off, USNM 227063.
Paratypes. Copulatory male, bl 3.2 mm, USNM 227064. 20 additional
specimens, some dissected for description, SIO.
Type-Locality. WHOI 169, 08O02.0-03.OYS,34'23.0-25.0'W, 587 m, collected
on 21 February 1967 during R/V Atlantis I1 cruise no. 3 1.
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. Anchibraziliensis refers to the occurrence "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
from cephalic dorsal surface. Cephalic frontal arch recessed into frons, not
protruding beyond vertex in dorsal view, nearly vertical in lateral view.
Cephalon lacking indentation at mandibular articulation. Widths of antennular
articles 1 sexually dimorphic, wider in adult males than in adult females: in
females, distance between medial comers of antennular insertions 0.19 (2 inds)
cephalon width; in males, 0.10-0.11 (2 inds). Maxillipedal epipod distally
scalloped. Male pleopod I distal tip with following paired setal groups: 5 fatbased 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 comer rounded, not projecting; exopod absent.
Description. Body Characters (Fig. 33A-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. 33A-C): All dorsal surfaces with few scattered fine setae.
Cephalon (Fig. 33D-F): All surfaces heavily calcified, especially at anterior
margins, with large platelike crystals in cuticle. In female, dorsal length 0.50
width, length 0.76 height. Ventral margin at posterior articulation of mandible
heavily calcified, with no indentation or notch.
Antennula (Fig. 33A-B, 34A-D): Strongly dimorphic sexually: male antennula
estimated length (not intact in any male specimens) greater than in female, with a
higher number of more robust articles. Female antennula length 0.39 body
length; 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 but shorter than lateral lobe, length 0.49
Wilson: Revision of the Lipomerinae
Figure 33. Mirnocopelates anchibraziliensis n. sp. 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, b14.4 mm. F, cephalon and mandible, ventral oblique view,
paratype male, b13.5 mm. G-J, mandibles, preparatory female, b14.4 mm. G , right mandible,
dorsal view. H, left mandible, ventral view, palp omitted. I, left incisor process and lacinia
mobilis, plan view. J, left mandible, incisor and molar processes, dorsal view.
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width in male, 0.59 in female; medial lobe of both sexes with approximately 4
broom setae. 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. 33F-J): Mandibles of both sexes heavily sclerotized and calcified.
Both mandibles with 3 distinct cusps on incisor processes. 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 flat curl.
Maxilliped (Fig. 34F): Ventral surfaces of basis, palp article 2, and epipodite
with cuticular ridges and few setae. Basis with 4-5 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. Endite distally
quadrate, length 0.51 total basis length. Palp article 2 width 2.0 endite width,
lateral length 2.0 medial length. Palp article 3 lateral 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.
Natatory Pereopods V-VI (Fig. 34G-H): Basically similar to those of
Mimocopelates longipes. Pereopod V-VI length-body length ratios 0.65, 0.54.
Pereopod V merus length 0.82 ischium length. Carpi V-VI length-width ratios
1.1, 1.3. Propodi V-VI length-width ratios 1.8,2.6.
Male Pleopod I (Fig. 35A-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.
Male Pleopod I1 (Fig. 35E-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. Exopod small, with fine setae on dorsomedial side.
Wilson: Revision of the Lipomerinae
Figure 34. Mimocopelates anchibraziliensis n. sp. A-B, right antennula, lateral and dorsal views,
paratype male, b13.5 mm. C-H,
paratype preparatory female, b14.4 mm. C-D,
dorsal views of left
antennula: articles 1 and 2, and articles 1-5. E, left maxillula. F, left maxilliped with enlargement
of distal tip of basis. G , right pereopod V, with enlargement of dactylus. H,right pereopod VI,
same scale as G .
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Bulletin, Scripps Institution of Oceanography
Female Pleopod I1 (Fig. 35K-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. Ventral surface with few setae. Distolateral margins
strongly recurved dorsally with approximately 11 plumose setae on each side.
Length 1.3 width; depth 0.41 length.
Pleopod I11 (Fig. 35H): 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. 351-J): Endopods of both limbs thick and triangular in
ventral view. Exopod of pleopod IV long, flattened, lobelike, with single long
plumose seta.
Uropod (Fig. 35M): Uropods small, unirarnous, recessed into ventromedial
margin of posterior pleotelson; only distal tip of endopod visible in lateral view.
Protopod medial length 0.56 distal width. Endopod 1.6 medial length of
protopod. Distal margin of protopod with few long setae, posterior margin
lacking projection.
Remarks. Mimocopelates anchibraziliensis n. sp. is a very distinctive species:
members are large, exceeding 4 mm as adults, the unirarnous uropods are tiny,
and the cephalon is enlarged and heavily calcified. In addition to these
characters, thr, flat, triangular male pleopods are distinctly different from the
robust, highly convoluted pleopods of M. longipes. In fact, the male pleopods I1
of M. anchibraziliensis are somewhat reminiscent of those seen in some
Munnopsidae sensu strict0 whose endopods, exopods, and intrinsic musculature
are reduced. This species was collected only in a bathyal transect of stations off
Recife, Brazil.
Wilson:Revision of the Lipomerinae
87
Figure 35. Mimocopelates anchibraziliensis n. sp. A-J, paratype male, b13.5 mm. A, pleotelson
and pereonite 6,ventral view. B-D,
pleopod I: B,lateral view with enlargement of ventral fat setae;
C, ventral view with enlargement of distal tip; D, dorsal view of distal half. E-G, pleopod II:
E, left side, ventral view; F, right side, lateral view; G, left side, enlarged dorsal view of distal tip.
H-J, right pleopods LII-V. K-L, pleopod 11, ventral and lateral views, paratype preparatory female,
b14.4 mm. M, uropod, holotype female, b14.2 mm,in situ, proximal portion seen through cuticle.
PHYLOGENY AND CLASSIFICATION
This section presents an evaluation of the systematic position of the
subfamily Lipomerinae Tattersall, wherein the monophyly of these ilyarachnidlike animals is demonstrated. Computer-assisted numerical phylogenetic
methods are used to compare the genera of the Lipomerinae with other major
munnopsid taxa in an extended outgroup study. A side effect of confirming the
monophyly of the Lipomerinae and their distinctiveness from the ilyarachnids is
a realignment of the Ilyarachnidae, the Eurycopidae, and the Munnopsidae into
one family. Characters that show relationships between the munnopsid taxa are
used with a bias toward interpreting the systematic position of the ilyarachnidlike eurycopids. As a consequence, some taxa may not be identified by
autapomorphies, because this analysis is designed to emphasize relationships
between taxa. Many munnopsid taxa, of course, have a variety of unique
specializations, but these characters were not the focus of the analysis. The
estimated phylogeny and the conclusions reached here provide hypotheses to be
tested in the future, although a preliminary conclusion concerning the
classification of the munnopsids is reached.
TAXA USED
The Munnopsidae sensu lato
The diversity of munnopsids and the limited information on many of them
requires a restriction in the number of taxa used in the phylogenetic analysis.
Four independent criteria, based on the desire to properly place the ilyarachnidlike eurycopids, established the subset of taxa (Table 6) used in this analysis: (1)
they are ilyarachnid-like eurycopids; (2) they are members of the subfamily
Eurycopinae as previously recognized (Wolff 1962); (3) they are the least
modified representatives of their group; (4) they are presumed to be closely
related to the Ilyarachnidae. Some previously-defined taxa may overlap, such as
the previous classification of Hapsidohedra n. gen. in the Ilyarachnidae (criteria
1, 2, and 4). All genera used in the analysis have been revised recently, or were
evaluated directly from specimens. These criteria include most munnopsids, but
the major taxa or genera not used are discussed below. The chosen taxa are
presumed to represent major monophyletic groups within the munnopsids.
The eurycopid subfamily Bathyopsurinae, with the genera Bathyopsurus
and Paropsurus, contains highly modified bathypelagic animals. This group may
be derived from a Munneurycope-like ancestor (Wolff 1962). This subfamily is
not included in the analysis because its genera have little in common with the
ilyarachnid-like eurycopids.
The eurycopid subfamily Syneurycopinae contains two genera,
Wilson:Revision of the Lipomerinae
89
Syneurycope and Bellibos, that include a fairly wide range of morphologies. The
subgenus B. (Bellibos) is the least modified with respect to the other munnopsids
because its cephalon is not fused to the first pereonite, and the natasomal
pereonites are not reduced in size. The species B. (B.) buzwilsoni Haugsness and
Hessler, 1979 is chosen as the syneurycopine representative in the analyses.
The Munnopsidae sensu strict0 contains a variety of morphologies, but can
be best represented by Paramunnopsis, which is the least derived member of the
family. This genus is superficially similar to the eurycopid Munneurycope in
overall appearance, which has been a source of taxonomic confusion (Wolff
1962). The type genus of the Munnopsidae, Munnopsis, can be scored almost
identically to Paramunnopsis for the characters used here, and therefore was not
included in the analysis.
The Ilyarachnidae has 5 genera with a basic body plan, and is well
established as monophyletic (Wolff 1962; Thistle and Hessler 1976). The least
modified genus, Ilyarachna, was chosen to represent this taxon.
Two eurycopid genera, Microprotus and Munnicope, were not included
because they 5re poorly described and only 1 specimen of the latter genus was
found in collections, eliminating the possibility of dissection. A preliminary
inspection of Munnicope showed that this genus has characters in common with
Munnopsurus so its omission from the analysis will not seriously hamper the
results. Microprotus has been redescribed (Wilson et al., in press) too late to
include in this analysis.
An Outgroup for the Munnopsidae
An effective phylogenetic analysis of the position of the Lipomerinae
among the munnopsids must include at least one additional outgroup to establish
the polarity of character changes, and to "root" the tree. Unfortunately, only one
explicit phylogeny of the Asellota has been published that includes the families
Ilyarachnidae, Eurycopidae, and Munnopsidae (Kussakin 1973). Wagele (in
preparation) will propose a new phylogeny for the Janiroidea, but his results have
become available too late to be included here. Kussakin's tree was presented
without an explanation of its construction, although it is probably based on the
taxonomic judgment of its author. In Kussakin's tree, the clade including the
families Ischnomesidae, Macrostylidae, and Pseudomesidae is the sister group to
the munnopsids. I find several problems with this hypothesis. First, the
Pseudomesidae has been submerged into the Desmosomatidae and the
Nannoniscidae (Svavarsson 1984). Second, both the Ischnomesidae and the
Macrostylidae are highly modified taxa that share few apparent apomorphies
with the munnopsids. Third, the entire phylogenetic structure of the Janiroidea
must be reconsidered. A recent phylogenetic analysis of the superfamilies of the
Asellota (Wilson 1987) shows that the Munnidae, the Santiidae (= Antiasidae),
the Paramunnidae, and the Abyssianiridae were derived before the Janiridae.
Bulletin, Scripps Institution of Oceanography
Figure 36. A comparison of third pleopods of various Asellota. A, Stenetrium, Stenetriidae,
Stenetrioidea. B , Pseudojanira, Pseudojaniridae, superfamily Pseudojaniroidea. C , Notasellus,
Janiridae, Janiroidea. D, Munna, Munnidae, Janiroidea. E,Acanthaspidia, Acanthaspidiidae,
Janiroidea. F, Amuletta, Munnopsidae, Janiroidea.
Wilson:Revision of the Lipomerinae
n
Figure 37. A comparison of third pleopods of various higher Janiroidea. A, Janirella, Janirellidae.
B, Dendrotion, Dendrotiidae. C , Thambema, Thambematidae. D, Mesosignum, Mesosignidae.
E, Rapaniscus, Namoniscidae. F, Ischnomesus, Ischnomesidae. G , Haploniscus, Haploniscidae.
H , Momedossa, Desmosomatidae. I , Macrostylis, Macrostylidae.
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Bulletin, Scripps Institution of Oceanography
The Janiridae was previously considered the most primitive taxon of the
Janiroidea, so the possible rooting of any evolutionary character analysis is
changed considerably (Wilson ibid.).
Given these problems, a search for munnopsid apomorphies shared with
other janiroideans was conducted. This included preliminary phylogenetic
analyses of all the families of the Janiroidea (Wilson 1985). The most obvious
specialization of the munnopsids is their ability to swim backward. This also
appears in other families as well, specifically the Desmosomatidae, and has been
used to relate the two groups (Hansen 1916; Kussakin 1965). This adaptation,
however, is probably attained independently in the two taxa. Sars (1899) noted
that both swim backward but do it quite differently, the munnopsids generally by
rapid jumps through the water, and the desmosomatids by a sustained walking
motion, which allows them to leave the bottom. The swimming setae are of quite
different forms: the desmosomatid swimming seta has setules only distally
(Hessler 1970), and the munnopsid seta has many setules from base to tip, giving
it a featherlike appearance (Wilson and Hessler 1980). The base of the
munnopsid swimming seta also has a specialized hinge and stop arrangement that
is not seen in the Desmosomatidae. The desmosomatids are closely related to the
Nannoniscidae (Siebenaller and Hessler 1977, 1981), and share apomorphies
with the Macrostylidae, especially in the mandible and in the fossorial
pereopods. A sister group relationship between the Desmosomatidae and the
munnopsids is not likely (Hessler 1970).
If one ignores the swimming specializations of the least modified
munnopsids, few apomorphies at the systematic level of the higher Janiroidea are
shared with other families (Wilson 1985). The basic janiroidean mouthparts,
antennulae, antennae, first pereopod, pleopods, and body form (not including the
swimming modifications) are observed in the least modified munnopsids. The
scanty evidence available to me indicates that the munnopsids arose early in the
diversification of the deep-sea isopods, and therefore have much in common with
more primitive shallow-water taxa, such as the Janiridae (sensu lato).
My survey of janiroidean synapomorphies revealed one munnopsid
apomorphy shared with the poorly known family Acanthaspidiidae: many
plumose setae on the distal tips of both rami of the third pleopod. Wolff (1962)
placed the Acanthaspidiidae and the Janirellidae in the Janiridae, although later
authors (Menzies and Schultz 1968; Kussakin 1973; Bowman and Abele 1982)
continued to recognize these families. Throughout the Janiroidea, the third
pleopod undergoes a series of reductions, both in size and in setation. In the
sister group to the higher Janiroidea, the Pseudojaniridae Wilson (1986a; 1987),
and in most of the within-group families, there are only 3 plumose setae on the
third pleopod endopod. None of the families, except the munnopsids and the
Acanthaspidiidae, has more than one plumose seta on the exopod (Figs. 36, 37).
(The non-monophyletic family Janiridae (Wilson and Wagele, in preparation)
currently contains genera, such as Janiralata, that have this apomorphy, although
Wilson:Revision of the Lipornerinae
93
these may also be closely related to the Acanthaspidiidae.) This setation of the
third pleopod may be a synapomorphy of the two families, and is evidence for
their common ancestry. The Janirellidae has more than 3 plumose setae on the
endopod of the third pleopod, and is, therefore, also a candidate for sister group
status with the munnopsids. The Janiridae may also function as an outgroup to
the munnopsids. This last family, however, is highly heterogeneous, and no
apomorphies apply to all janirid taxa (Wilson and Wagele, in preparation). For
the character studies, the Janiridae was limited to genera that had enlarged
accessory (third) claws on the pereopods. In the character studies, all three
families (Acanthaspidiidae, Janirellidae, Janiridae) were used as outgroups.
Munnopsid trees, however, were rooted using only the Acanthaspidiidae because
most characters of the three outgroup families were similar.
CHARACTER ANALYSIS OF THE MUNNOPSID TAXA
The natatory morphology unites all the munnopsids, but the included taxa
vary enormously in the their overall body plan (Fig. I), and in the form of less
well understood features such as the cephalic frons and the pleopods. In this
section, morphological data of the munnopsid taxa are evaluated for useful
synapomorphies. The presumed sister group Acanthaspidiidae and other
outgroups permit an assessment of the character polarities. Most characters
discussed below are presumed synapomorphies of two or more munnopsid taxa.
Their usefulness was determined by preliminary analyses of the munnopsid
phylogeny.
Characters Found in All Munnopsids
The munnopsids have three synapomorphies that distinguish them from all
other Janiroidea. Because the characters consist of complicated morphologies
that are not easily lost without leaving evidence of their presence in ancestors,
they were evaluated in the phylogenetic analysis using the Camin-Sokal
parsimony method, and are given an a priori weight of 2. They are listed as
characters A-C in the tables.
The first character is the most obvious: the swimming adaptations, which
consist of paddlelike pereopods V-VII with fringing plumose setae on the carpi
and the propodi, and enlargement of the musculature powering these limbs.
Associated with the pereopodal features is an integrated natasome, a
characteristic modification of the posterior pereonites and the pleotelson, making
them more or less streamlined for posterior locomotion. So much variability in
the natasome occurs throughout the munnopsids, however, that defining specific
features common to all natasomes is difficult. Nevertheless, the natasome is
recognized as a secondary division of the body, in which the pleotelson and
posterior three thoracomeres function as a unit. A coalescence and anterior
placement of neuronal ganglia of pereonites 5-7 may be diagnostic of the
94
Bulletin, Scripps Institution of Oceanography
natasome. This was first pointed out by Hult (1941), although his observations
have been largely ignored by later workers. All other Janiroidea observed by
Hult and myself have a more typical ladderlike arrangement. Some variation in
the form and position of the fused ganglia appears, but they are fused or closely
associated in all munnopsids examined so far. This coalescence is correlated
with the presence of the natasome, which argues against the independence of this
feature, but emphasizes the monophyletic derivation of the munnopsids. Hult
(1941) even wished to create, on the basis of the fused ganglia, a munnopsid
taxon separate from the remaining Janiroidea (which was recognized in his paper
as a family, not a superfamily as it is now). This possibility is discussed in the
classification section.
The second character is evidently independent of the first character: cupped
or troughlike dactylar claws that enclose the paired distal sensillae. This
condition is illustrated in Wilson and Thistle (1985, their Fig. 3D) for the first
pereopod, but it occurs on all munnopsid pereopods where the claws are not
reduced or greatly altered. Unmodified dactylar claws with free sensillae are
found in the Acanthaspidiidae and Janirellidae.
A third character, shown by Wolff (1962) to occur in all the munnopsid
families, is a "plate-like" first segment of the antennula. This character can be
described as a flattened flange projecting laterally from the basal part, thereby
broadening the first segment. The medial part of the segment is variously
thickened in many of the munnopsids, with some having a medial lobe. In the
Acanthaspidiidae and other janiroideans, the antennular first segment is more or
less tubular. This munnopsid synapomorphy may not be completely independent
from the swimming adaptation: the flattened lateral flange and medial thickening
may improve the hydrodynamic characteristics of the antennula when the animal
is swimming backward. This antennular character is retained in the analysis
because it is not directly associated with natasome development, and may have
evolved after backward swimming. Complex adaptations are not likely to have
appeared fully developed in single ancestors, but may have appeared in steps.
The swimming adaptations of the munnopsids may be analogous to the evolution
of the janiroidean sexual structures (Wilson 1986b 1987) where major changes
occurred independently but resulted in a highly successful (in terms of taxonomic
diversity) reproductive morphology.
Fusion of the Natasomal Segments
The varied fusion of pereonites 5-7 is responsible for much of the
morphological diversity in the munnopsids. The functional necessity of a
strengthened cuticular framework for the powerful swimming muscles may be a
driving force in the observed patterns of fusion seen in the munnopsids. In fact,
the segmental arrangement of muscles is often lost by the migration of the
internal muscular attachments into the segments anterior to their pereopodal
Wilson: Revision of the Lipomerinae
95
origins. Because fusion of the natasomal pereonites is a general trend in all
munnopsids, with frequent apparent convergences, only certain patterns could be
used. These characters were analyzed using Carnin-Sokal parsimony, and were
given an a priori weight of 2.
The plesiomorphic state is complete flexibility between pereonites 5-7 and
the pleotelson. This state is seen in Munnopsurus and in Munnicope. The latter
genus is most unusual in that pereonites 5-7 are the same size, and have
relatively small pereopodal musculature. In this regard, Munnicope may be the
least derived munnopsid.
Fusion of the natasomal pereonites may have begun on the ventral surface,
resulting eventually in complete obliteration of the segmental boundaries. This
is best seen in Eurycope (Wilson and Hessler 1980, 1981), but occurs in most of
the other munnopsid genera. Notable exceptions are the Ilyarachnidae, Amuletta,
and Hapsidohedra. The last genus is morphologically atypical in that the
natasome is strongly flexed ventrally, possibly a factor in its retention of free
ventral natasomites. The Ilyarachnidae are known to burrow backwards (Hessler
and Sttomberg, in preparation), suggesting that some flexibility in their
wedgelike natasome is necessary. Little is known of Amuletta, so the function of
natasomal flexibility in this genus cannot be evaluated. In Storthyngura, the
natasomal pereonites vary from a condition where the ventral sutures are visible,
but not flexible, to a totally fused condition. Fusion of the ventral natasomite
boundaries was not used because of this variability, and because it introduces
many steps into the cladograms.
In dorsal fusion of the natasomites, several patterns emerge. All
Lipomerinae, except for Coperonus, have tergites of pereonites 6 and 7 that are
fused medially (character 1 in list below). The eurycopids Belonectes,
Disconectes, and Tytthocope have pereonites 5 and 6 fused dorsally (character 2).
Lastly, complete fusion of all the natasomal pereonites occurs in Baeonectes,
Acanthocope, some species of Storthyngura, and in the Syneurycopinae. This
last character state may not indicate real shared ancestry between these taxa
because it 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 may be derived independently of the
transition to the completely fused natasome. Therefore, the completely fused
state of the natasome is not used in the analysis.
Comparative Sizes of the Natasomal Pereonites
A great variety in pereonites 5-7 sizes is seen in the munnopsids, with any
one of these 3 segments dominating the natasome, depending on the taxon. The
primitive state, subequal pereonites, is found in few taxa, i.e., Munnopsurus and
Munnicope.
Bulletin, Scripps Institution of Oceanography
In Eurycope and many other genera, pereonite 7 becomes enlarged. An
extreme is seen in the Munnopsidae sensu stricto, where the last pereonite is
large, and pereonite 5 becomes compressed dorsally along the body axis to a
narrow band. Unfortunately, the inclusion of this character state as a terminal
apomorphy into the analysis considerably worsened the homoplasy level,
indicating multiple derivations. An alternative hypothesis of character derivation
is that many munnopsids are derived from an ancestor with an enlarged pereonite
7, and subsequently the size of the pereonite 7 was reduced independently in
many of the taxa. Under such a derivation, the subequal natatory pereonites of
Munnopsurus are difficult to score, being either secondary or primary. 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 that unites all Lipomerinae is a reduced seventh pereonite.
In two genera, Lipomera and Mimocopelates, the last pereonite is rudimentary,
and in the three other Lipomerinae, it is only a thin band that may be fused to the
anterior segment. Tytthocope also has a 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 (character 3).
Hindgut Morphology
In all outgroups and most of the munnopsids, the hindgut anterior to the
pleotelson is straight, or nearly so. A bent or coiled gut is a useful
synapomorphy of the somewhat dissimilar subgenera of Lipomera. It is
included here to permit defining these three subgenera as a monophyletic group
in the analysis (character 4).
Spines on Body
The presence of body spines on munnopsids is unusual, although the genera
Acanthocope, Storthyngura, and Microprotus are known to have them. At first,
this might seem to be a derived character within the munnopsids, but the
spination of these three genera is somewhat similar to the dorsal and lateral
spines of the Acanthaspidiidae. On the other hand, the body plans of these
spinose munnopsids are highly modified, indicating that they have diverged
considerably from the munnopsid ancestor. Because the spines in the munnopsid
taxa could be a reversion to the ancestral state, or the stem munnopsid may not
have had spines, they are analyzed using the Wagner parsimony method
(character 5).
Rostrum
The rostrum, an anterior projection of the cephalon, is an ancestral
character of the Janiroidea (Wilson 1987), and is seen in somewhat modified
Wilson: Revision of the Lipornerinae
97
form in the Acanthaspidiidae (Fig. 38A). Most munnopsids have lost the
rostrum, and the cephalon has a nonprotruding dorsal vertex (Fig. 38C-G). In
some genera (Munneurycope 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. 38B),
Tytthocope, Disconectes, Belonectes, and Baeonectes (Wilson and Hessler 1980,
1981; Wilson 1982a), although its form often deviates considerably from the
primitive projection seen outside the munnopsids. In some of these taxa, the
rostrum becomes very broad and rounded, and does not project from the frons.
Because both a narrow, projecting rostrum and a broad, rounded rostrum are seen
within some genera (Eurycope, Disconectes), the rostrate genera are scored as
having the plesiomorphic state of the rostrum (character 6).
Frontal Arch
The "frontal arch" is defined as an archlike thickening of the cephalic frons,
providing a strengthened bridge between the fossal regions of the clypeus on
either side of the frons. Much of the variety in the munnopsid frons is a result of
changes in the form of the frontal arch. Eurycope and other rostrate genera show
no evidence of having had a frontal arch. Some species of Eurycope have a
pair of vertical ridges running from the clypeus to the rostrum forming an
inverted "V" (Fig. 38B), but these same ridges are seen in the Janiridae. An
incipient frontal arch is seen on the smoothly protruding frons of Paramunnopsis:
the region just above the clypeus is flattened and arc-shaped (Fig. 38C). In
Munneurycope (Fig. 38D) and Storthyngura, a fully developed frontal arch is
seen, where the arch is a projection from the ventral part of the frons. These two
genera also have the inverted "V1'-shapedridges of Eurycope, demonstrating that
these ridges are not modified frontal arches. In other genera, the arch shows a
variety of forms, appearing massive in some, such as Munnopsurus (Fig. 38E),
Acanthocope, and Ilyarachna (Fig. 38F). The frontal arch of the Lipomerinae
(Fig. 38G) 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 of other taxa. These
character states form a linear transformation series: no frontal arch, incipient
frontal arch, well-developed frontal arch (in a variety of shapes), and a reduced
and flattened frontal arch (character 7).
Mandible
At first, components of the mandible appeared to offer a variety of useful
characters. Preliminary phylogenetic analyses showed, however, that their use
often introduced a great deal of homoplasy. For example, an enlarged, rounded,
and sclerotized molar process seemed useful because most Lipomerinae had this
Bulletin, Scripps Institution of Oceanography
Figure 38. Cephalons of an acanthaspidiid and several mumopsids in frontal oblique view.
A, Acanthaspidia. B, Eurycope. C, Paramunnopsis. D, Munneurycope. E , Munnopsurus.
F, Ilyarachna. G, Coperonus. The left antemulae and left antennae have been removed to expose
the frons of the cephalon. The mandibular palps on the left sides are also omitted. The
maxillipedal palps of D and F are missing. Indications on figures: c = clypeus; f = frontal arch;
if = incipient frontal arch; 1 = labrum; m = mandible; r = rostrum.
Wilson:Revision of the Lipomerinae
99
apomorphy. Nevertheless, this character state 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 seemingly useful character
state was a reduced molar process, although each taxon that might have been
scored for such a reduction had a unique shape, again indicating independent
derivation in each case.
An apomorphy of Ilyarachna used in the analysis was the presence of an
enlarged, rounded, heavily sclerotized incisor process (character 8). A similar
incisor is also found in Munnopsis. This genus was not included in the analysis
because it is highly modified, and is closely related to Paramunnopsis, a
possessor of a primitive, unmodified incisor process. The modified incisor of
Munnopsis therefore is regarded as an independent derivation.
The second apomorphy used in the analysis was the absence of the
mandibular palp, found only in Amuletta (character 9). The palp is also missing
in the derived ilyarachnids Aspidarachna and Echinozone, which were not used
in this analysis. Wilson and Thistle (1985) concluded that the ancestral
ilyarachnid had a mandibular palp. Its absence both in some of the Ilyarachnidae
and in Amuletta may indicate a propensity for this loss if a common ancestry of
the two groups is accepted. The palp is also lost in some genera of the
Munnopsidae sensu stricto, although it is present in the least modified
Paramunnopsis. Here again, the loss of the palp is likely to be convergent at the
level of the munnopsids, but it is included to define Amuletta.
Ambulatory Pereopods
Pereopods II-IV are the ambulatory pereopods, with pereopod I (sometimes
11) performing a manipulative function, and pereopods V-VII being used for
swimming (or burrowing). A primitive condition for the pereopods II-IV is all of
them more or less the same length or perhaps becoming 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 munnopsids are
collected with their fragile ambulatory pereopods broken off, enough information
exists, in the form of published descriptions and occasional intact specimens in
the collection, to use pereopod lengths in the analysis.
The ambulatory pereopods have several useful features. First, bases III-IV
in some taxa are shorter than basis I1 (character 10). 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. These two substates are placed in a linear
transformation series. Second, the entire pereopods III-IV are greatly longer than
pereopod I1 in many taxa (character 11). Although both apomorphies are
undoubtedly functionally related, their distribution among the munnopsids
indicates they were attained independently. A third apomorphy scored is a
prehensile form of the second pereopod (character 12). This last character is
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Bulletin, Scripps Institution of Oceanography
difficult to verify in some cases but was included because Wolff (1962) used it as
a diagnostic family-level character. Because of the uncertainty in its derivation,
the prehensile pereopod I1 character is analyzed using the Wagner parsimony
method, which permits reversions. A fourth character state suggests a common
ancestry for Munnopsurus and Munneurycope: elongate bases of the first
pereopods (character 13).
Natatory Pereopods V-VII
The natapods display a variety of morphologies that are easily classified
into a few discrete states. Because natatory pereopods are plesiomorphic within
the munnopsids, but autapomorphic at the level of the Janiroidea, polarities are
assigned by analogy, rather than by direct homology. Because pereopods V-VII
are approximately the same size or perhaps increasing in length posteriorly in the
outgroup taxa, the same is assumed for the munnopsids even though the outgroup
pereopods have an ambulatory form, and the munnopsids have natapods instead.
The comparative lengths of the pereopod V-VII bases require the analogy
assumption. In the outgroup Acanthaspidiidae, all the pereopodal bases are
similar in length, as observed in many munnopsids. In others, bases V-VII are
distinctly shorter than bases I-IV. Not all Lipomerinae are alike in this character:
Coperonus and Mimocopelates have shortened bases as in Disconectes and
Belonectes. Because character state reversals are possible in the lengths of the
bases, this feature (character 14) was interpreted in the phylogenetic analysis
using Wagner parsimony.
The species of Mimocopelates have a useful synapomorphy that justifies
retaining M. anchibraziliensis in the genus and recognizing the genus as
monophyletic: an elongated merus of pereopod V (character 15). In most
munnopsids, this segment of the fifth pereopod is shorter than its basis, but in
Mimocopelates it is distinctly longer. Although this character may be have
appeared only once without reversions, the Wagner parsimony method was used
because reversals in length could be possible.
The pereopodal dactyli have several characters useful for the munnopsid
phylogeny (character 16). In the outgroups and many of the genera of the
munnopsids, the dactyli of pereopods V-VII are fairly large, although generally
shorter than the propodi. A defining apomorphy of the Munnopsidae sensu
strict0 is the complete absence of the dactyli on the natatory pereopods. Three
genera of the Lipomerinae show a different apomorphy: the dactylus of pereopod
V is reduced to a tiny lobe, and the more posterior pereopods have large dactyli.
These apomorphies are scored as states of the same character and are used in the
analysis via nonadditive binary coding with Camin-Sokal parsimony.
Two taxa considered here lack pereopods VII as adults: Mimocopelates and
Lipomera. Absence of the last pereopods may be a paedomorphic trend
throughout all the Janiroidea that may happen many times (Wilson 1976).
Wilson:Revision of the Lipomerinae
101
Mimocopelates also has a reduced pereopod VI (character 17), indicating a trend
toward greater reliance on the fifth pereopod for swimming. Two subgenera of
Lipomera have subequal pereopods V and VI, although the more derived L.
(Paralipomera) species also have a reduced pereopod VI. Because the subgenera
of Lipomera are considered a single taxon in this analysis (see character 4), the
genus is scored as having subequal anterior natapods, with the independent
derivation of the apomorphy, reduced pereopod VI, in both Mimocopelates and
L. (Paralipomera).
In a majority of the munnopsids, the last pereopod is nearly the same size
as the next to the last, both in length and breadth of the broadened carpi and
propodi. Tytthocope has a defining apomorphy in that the last pereopod is
distinctly smaller 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 has long
swimming setae, which is unlike the diminutive last pereopod of Tytthocope.
Therefore, only Tytthocope is scored as having a reduced but natatory pereopod
VII (character 18, state 1). An unrelated reduction of the last pereopod is seen in
the Lipomerinae and in the Ilyarachnidae. They both have last pereopods in
which the paddles have become narrow and most of the plumose setae are lost
(character 18, state 2). This derived state resembles a walking leg, although the
presence of a few plumose setae betrays its natatory ancestry. Because this
apomorphy is incompatible with many others used in the phylogenetic analysis,
it may have been derived independently in the Ilyarachnidae and in the
Lipomerinae. As mentioned above, Lipomera and Mimocopelates take the
reduction one step further: the last pereopod is degenerate or absent (character
18, state 3).
Cleft in the Tip of Female Pleopod I1
A number of munnopsids, including the ilyarachnid-like eurycopids, have a
notch or cleft in the tip of the female opercular pleopod. The polarity of this
character is uncertain. In some munnopsid genera, the notch is large and seems
to wrap the pleopod around the preanal ridge, thus leaving the anus exposed, as
in the Janiridae. In the Acanthaspidiidae and the Janirellidae, the anus is covered
by a distal extension of the female pleopod 11, found also in a number of the
munnopsids, notably Eurycope and Munnopsurus. In many munnopsids, the
anus is covered, but a notch is present, indicating that the two sides of the cleft
have grown together over the anus. These are scored as having the cleft. In
some species of the Lipomerinae, the cleft is not seen, and the second pleopod
covers the anus. The cleft does occur in congeners and closely related genera,
which indicates that it is fused, not absent. The genus Lionectes is scored as
having a fused cleft. Acanthocope has no cleft in the female second pleopod, but
the anus is not covered. The Syneurycopinae also have a reduced female
operculum and an exposed anus, although they have a cleft. Whether the absence
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Bulletin, Scripps Institution of Oceanography
of the cleft is primary or secondary in Acanthocope is unknown, so this trait is
left indeterminate for this genus. The transformation series for this character is
"no notch" to "notch or cleft" to "cleft fused," with rooting at either "no notch" or
"notch (character 19). The transition between the first two states is interpreted
with the Wagner method, and the second with the Camin-Sokal.
Proximal Fusion of Male Pleopods I1
A synapomorphy of all the genera of the Munnopsidae sensu strict0 is a
fusion to greater or lesser degrees of the proximal margins of male pleopod I1
(character 20); this character was used by Wolff (1962) to help diagnose the
family. This is a paedomorphic character because the male second pleopod
passes through a state intermediate to the totally fused female form (janiroidean
mancas are morphologically similar to females regardless of their ultimate sex)
and the unfused, separated pleopods of the adult male. This character is analyzed
using the Wagner method because reversions could be possible.
Pleopods 111-IV
Supernumerary plumose setae on the exopod and endopod of pleopod I11
indicate a sister group relationship between the Acanthaspidiidae and the
munnopsids (see Fig. 36). If the homology between acanthaspidiid and
munnopsid pleopodal setation is accepted, then the plesiomorphic state within
the munnopsids is a pleopod I11 with many plumose setae on both the endopod
and the exopod. All pleopod setation characters discussed below are reduction
characters and therefore should be weighted less than uniquely derived
apomorphies. Because the setae are less likely to be regained after they are lost,
the Camin-Sokal parsimony method was applied to them.
The loss of plumose setae on the exopod of pleopod I11 shows three states,
each of which may appear independently. This interpretation was reached by
trying several transformation series in the preliminary analyses, and picking the
one that yielded the fewest steps in the overall tree. Two or three plumose setae
on the exopod defines the Lipomerinae (character 21, state l), but is also seen in
Tytthocope. A single seta occurs on the exopod of Baeonectes (character 21,
state 2), and a number of the genera, including Eurycope, have no plumose setae
at all (character 21, state 3).
In many munnopsid taxa, the endopod of pleopod I11 has only three
plumose setae, a reversion to the plesiomorphic state at the level of the Janiroidea
(character 22). Within the munnopsids, however, it must be considered an
apomorphy.
The exopod of pleopod IV also has plumose setae in many of the
munnopsids. The Acanthaspidiidae have exopods with many plumose setae,
indicating that this is the plesiomorphic state. The presence of only a single seta
Wilson:Revision of the Lipomerinae
103
on the exopod (character 23 - state 1) occurs in the Lipomerinae, but this state is
seen in other taxa. A few taxa - Acanthocope, Bellibos, and Paramunnopsis lack plumose setae on the exopod (character 23 - state 2). Parsimonious trees
result from a linear transformation series: many setae to one seta to none.
Uropods
The munnopsids show a great variety in the form of the uropods, and it was
originally hoped these could provide some characters for the analysis. However,
the uropodal form is unique to each taxon, and attempts to score general
characters were fraught with many assumptions. Moreover, when simply defined
characters, such as whether the protopod is broad or tubular, are put into the
analysis, they often added nearly as many steps as taxa scored with the
apomorphic state. The uropod varies too much at the level of the munnopsids to
be useful for this analysis.
Within the Lipomerinae, however, the uropod shows a few decipherable
trends. The protopod is least modified in Coperonus, being large and robust
(character 25, state 0) with a medial projection (character 24, state 0) bearing
unequally bifid setae. This is similar to the form seen in Eurycope or Amuletta.
In Mimocopelates, the uropod is greatly reduced in size (character 25, state I),
but still retains the protopodal medial projection in one species, M. longipes. In
the three remaining genera, the medial projection on the protopod is lost
(character 24, state 1) with this segment being longer and more flattened
(character 25, state 2). The presence or absence of the medial lobe on the
protopod has an uncertain rooting within the munnopsids. If one uses the
outgroup state, then "no medial lobe" (state 0) would be ancestral because the
Acanthaspidiidae and the Janiridae have more or less tubular protopods, as do
many munnopsids. The scattered distribution of apparently similar broadened
protopods in the munnopsids casts doubt on this interpretation. Because the
plesiomorphic state is uncertain, the medial lobe character is analyzed with the
Wagner method. The size of the protopod (character 25) is analyzed with the
Carnin-Sokal method, because the specialized flattened protopod is not likely to
revert to the more primitive tubular state. The enlargement or reduction of the
protopod from the primitive state found in Coperonus probably happened
independently, so the two derived states are nonadditive in the analysis.
Bulletin, Scripps Institution of Oceanography
LIST OF CHARACTERS
This list contains the characters and their states used in the mumopsidlevel phylogenetic analyses. 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). The previous section explains the ordering of multistate characters.
Following the character states, the parsimony method (C = Camin-Sokal;
W = Wagner) and the a priori character weight (Wt = 1 or 2) is indicated
parenthetically. The methods section discusses weighting rationales. The
distribution of the character states is shown in Table 6, and the analysis data with
binary-coded, multistate characters is given in Table 7.
Body without (0) or with (I) natasome and natapods. (C, Wt = 2).
Dactylar claws of pereopods simple, not enclosing sensillae (0), or
troughlike, enclosing sensillae (1). (C, Wt = 2)
First segment of antemula tubular (0) or broadened with a flattened lateral
flange, and thickened medially (1). (C, Wt = 2)
Natasomites dorsally unfused (0) or only pereonite 5 and pereonite 6 fused
medially (1). (C, Wt = 2)
Natasomites unfused dorsally (0) or only pereonite 6 and pereonite 7 fused
medially (1). (C, Wt = 2)
Pereonite 7 present (0) or reducedlabsent (1). (C, Wt = 1)
Hindgut anterior to pleotelson straight (0) or hindgut with bendhoop (1).
(C, Wt = 2)
Spines on dorsal and lateral surface of pereon and pleotelson (0) or no
spines (1). (W, Wt = 1)
Rostrum present (0) or absent (1). (C, Wt = 2)
No frontal arch (0), incipient frontal arch (I), frontal arch (2), frons flat,
arch reduced (3). (C, Wt = 2)
Mandible: incisor process normal (0) or enlarged and heavy (1).
(C, Wt = 2)
Mandibular palp present (0) or absent (1). (C, Wt = 1)
Ambulatory pereopod bases approximately same length (0), bases 111-IV
shorter than basis I1 (I), or bases 111-IV length near width and much shorter
than basis I1 (2). (W & C, Wt = 2)
Wilson: Revision of the Lipornerinae
Pereopod 111-IV similar in length to pereopod I1 (0) or much longer (1).
(W, Wt = 1)
Pereopod I1 simple walking leg (0) or somewhat robust and prehensile (1).
(W, Wt = 1)
Pereopod I basis length subequal to bases 11-IV (0) or much longer (1).
(W, w t = 1).
Pereopods V-VII bases: near same length IV (0) or shorter than (1) basis
IV. (W, Wt = 1)
Pereopod V merus shorter (0) or longer (1) than basis. (W, Wt = 2)
Pereopod V-VII dactyli long (0) or rudimentary/absent (1) or only
pereopod V dactylus rudimentary/absent (2). (C, Wt = 2)
Pereopod VI near same size as pereopod V (0) or smaller (1). (C, Wt = 1)
Pereopod VII near size of pereopod VI (0), smaller than pereopod VI but
functionally natatory (I), smaller than pereopod VI with narrow carpi and
propodi (2), or rudimentary/absent (3). (C, Wt = 1)
Pleopod I1 of female without (0) or with notch or cleft in distal tip (1) or
cleft fused (2). (W, Wt = 2; C, Wt = 1)
Pleopods I1 of male proximally not joined (0) or joined (1). (W, Wt = 2)
Pleopod 111: exopod distal tip with many plumose setae (O), 2 or 3 plumose
setae (I), 1 plumose seta (2), or none (3). (C, Wt = 1)
Pleopod 111: endopod distal tip with more than 3 plumose setae (0) or 3 or
less plumose setae (1). (C, Wt = 1)
Pleopod IV: exopod with many plumose setae (0), 1 plumose seta (I), or
no plumose setae (2). (C, Wt = 1)
Characters analyzing the within-group relationships of the Lipomerinae.
24.
Uropodal protopod without (0) or with (1) medial projection. (W, Wt = 2)
25.
Uropodal protopod small (0), reduced (I), or enlarged and flattened (2).
(C, Wt = 2)
Bulletin, Scripps Institution of Oceanography
TABLE 6.
Distribution of character states in selected munnopsid taxa.
CHARACTER
Acanthaspidiidae
Acanthocope
Amuletta
Baeonectes
Bellibos
Belonectes
Betamorpha
Coperonus
Disconectes
Eurycope
Hapsidohedra
Ilyarachna
Lionectes
Lipomera
Mimocopelates
Munneurycope
Munnopsurus
Paramunnopsis
Storthyngura
Tytthocope
A
B
C
1
2
3
4
5
6
7
8
9
1
0
1
1
Wilson:Revision of the Lipornerinae
TABLE 6. (continued)
Distribution of character states in selected munnopsid taxa.
CHARACTER
12 13 14 15 16 17 18 19 20 21 22 23 24
Acanthaspidiidae
0
0
0
0
0
0
0
0
0
0
0
0
-
Acanthocope
0
0
1
O
O
O
O
?
0
0
1
2
0
Amuletta
?
0
0
0
0
0
0
1
0
0
0
0
-
Baeonectes
0
0
1
0
0
0
0
0
0
2
1
1
-
Bellibos
0
0
0
0
0
0
0
1
0
0
1
2
-
Belonectes
0
0
1
0
0
0
0
0
0
3
1
1
-
Betamorpha
0
0
0
0
0
0
0
1
0
0
0
0
-
Coperonus
0
0
1
0
2
0
2
1
0
1
1
1
1
Disconectes
0
0
1
0
0
0
0
0
0
3
1
1
-
Eurycope
0
0
1
0
0
0
0
0
0
3
1
1
-
Hapsidohedra
0
0
0
0
0
0
2
1
0
1
1
1
0
Ilyarachna
1
0
0
0
0
0
2
1
0
0
0
0
-
Lionectes
0
0
0
0
2
0
3
2
0
1
1
1
0
Lipomera
0
0
0
0
0
0
3
1
0
1
1
1
0
Mimocopelates
0
0
1
1
2
1
3
1
0
1
1
1
1
Munneurycope
0
1
1
0
0
0
0
0
0
3
1
1
0
Munnopsurus
?
1
0
0
0
0
0
0
0
0
0
1
-
Paramunnopsis
0
0
0
0
1
0
0
0
1
0
1
2
-
Storthyngura
0
0
0
0
0
0
0
1
0
0
0
0
-
Tytthocope
0
0
1
0
0
0
1
0
0
1
1
1
-
See text for a description of the characters. Characters 24 and 25 were evaluated for only the
Lipomerinae, Acanthocope, and Munneurycope. Character states that are not numbers: "B"=
having both states, "?" = state unknown or indeterminate.
Bulletin, Scripps Institution of Oceanography
,
TABLE 7.
Character-Taxon data matrix of selected munnopsids used in phylogenetic analysis.
CHARACTER
A B C 1 2 3 4 5 6 7 7 7 8 9 1 0 1 0 1 1 1 2
Acanthaspidiidae
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Acanthocope
1
1
1
0
0
0
0
0
1
1
1
0
0
0
0
0
0
0
Amuletta
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
O
?
?
Baeonectes
1
1
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
Bellibos
1
1
1
0
0
0
0
1
1
1
1
0
0
0
1
0
1
0
Belonectes
1
1
1
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
Betamorpha
1 1 1 O O O O 1 1 1 1 O O O B
0
1
0
Coperonus
1
1
1
0
0
1
0
1
1
1
1
0
0
0
0
0
0
0
Disconectes
1
1
1
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
Eurycope
1
1
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
Hapsidohedra
1
1
1
0
1
1
0
1
1
1
1
1
0
0
0
0
0
0
Ilyarachna
1
1
1
0
0
0
0
1
1
1
1
0
1
0
1
1
1
1
Lionectes
1
1
1
0
1
1
0
1
1
1
1
1
0
0
0
0
0
0
Lipomera
1
1
1
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
Mimocopelates
1
1
1
0
1
1
0
1
1
1
1
0
0
0
0
0
0
0
Munneurycope
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
Munnopsurus
1
1
1
0
0
0
0
1
1
1
1
0
0
0
O
O
O
?
Paramunnopsis
1
1
1
0
0
0
0
1
1
1
0
0
0
0
1
1
1
0
Storthyngura
1
1
1
0
0
0
0
0
1
1
1
0
0
0
1
0
1
0
Tytthocope
1
1
1
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
Wilson:Revision of the Lipomerinae
TABLE 7. (continued)
Character-Taxon data matrix of selected munnopsids used in phylogenetic analysis.
CHARACTER
APRIORIWEIGHTS
13 14 15 16 16 17 18 18 18 19 19 20 21 21 21 22 23 23
1
1
2
2
2
1
1
1
1
2
1
2
1
1
1
1
1
1
Acanthaspidiidae
Acanthocope
Amuletta
Baeonectes
Bellibos
Belonectes
Betamorpha
Coperonus
Disconectes
Eury cope
Hapsidohedra
Ilyarachna
Lionectes
Lipomera
Mimocopelates
Munneurycope
Munnopsurus
Paramunnopsis
Storthyngura
Tytthocope
Multistate characters have been factored to binary states. Character states that are not numbers:
"B" = having both states, "?" = state unknown or indeterminate.
Bulletin, Scripps Institution of Oceanography
RESULTS OF PHYLOGENETIC ANALYSES
Munnopsid Cladograrns
A variety of trees resulted from an extensive series of analyses using both
PHYLIP and PHYSYS programs. None of them resulted in highly parsimonious
trees: the homoplasy level varied from 42% to 67% more steps than one change
per character: the a priori weighting scheme found trees that were 59 unweighted
steps long, and the successive weighting trees had 60 unweighted steps. These
parsimony values yield overall consistency indices of 0.61 and 0.60, respectively.
Figures 39-40 show example trees from each of the weighting schemes used,
illustrating the major differences in topology encountered in most analyses.
Other trees found using the data were variations of these two trees. The shortest
trees were derived from Wagner algorithms either using defined (55 steps) or
undefined (5 1 steps) transformations for multistate characters. These strictly
Wagner trees had topologies similar to the mixed parsimony method trees, but
they were unacceptable because unlikely reversals occurred, such as the return of
a lost dactylus on the pereopods. A greater variety of trees resulted from a
compatibility method implemented by thresholds in ITERMIX, but too few
characters were included in the trees for defining the important branches.
The two example trees in figures 39-40 show much homoplasy in the
setation and reduction characters, but also in other characters. A notable
convergence is the multiple derivation of the frontal arch from the incipient
frontal arch. The incipient frontal arch of Paramunnopsis may be reinterpreted
as a reduced form of the full frontal arch, thus shortening the trees by several
steps. On the other hand, the distribution of frontal arch character states is not
well known, especially in the other genera of the Munnopsidae sensu stricto. For
this study, the interpretation of the frontal arch is not changed, but further
research on variation in this character is desirable.
The trees permit predictions for the character states that have unknown or
uncertain interpretations in specific taxa. Amuletta may have the advanced state
of character 11 (pereopods 111-IV much longer than pereopod 11). Munnopsurus
may have the primitive state of character 12 (unmodified pereopod 11).
Betamorpha, which shows both states of character 10 (0 or l), should have the
advanced state, pereopod 111-IV bases short, assigned to its immediate ancestor; a
reversion to unshortened bases then occurs within the genus. The female
pleopod I1 of Acanthocope is probably derived from a pleopod that had a notch
or cleft. Use of these predictions in the data does not change the form of the
trees, although they may generate more parsimonious trees.
Wilson:Revision of the Lipomerinae
Interpretation of the Cladograms
The cladograms described above show a complexity that is somewhat
difficult to interpret. Two questions arise at this point: Is the nesting hierarchy
of these cladograms any more parsimonious than that of past classifications?
How robust or meaningful are these results? The first question may be evaluated
by generating a cladogram based on past classifications and comparing its
parsimony and consistency to those in Figures 39 and 40. The second may be
tested by using a bootstrap resampling algorithm on the data (Felsenstein 1985).
Finally, a consensus tree shows the monophyletic groups that appear in all trees
generated by the a priori and successive weights data.
Figure 39. Cladograrn of selected munnopsid genera. One of the trees generated using conservative
a priori weights in the program ITERMIX. It has a parsimony value of 59 unweighted steps.
Character meanings are described in text. The character changes - straight lines crossing branches are marked to show where homoplasy has occurred: a closed circle is a convergence, and a closed
square is a reversion. Character changes marked by dotted lines are uncertain changes. The
character changes for the terminal taxa are indicated by lower-case letters. Their meanings are as
0
3
0
7
2
2
follows: a = 213; b = 21'; c = 3, 18', 21'; d = 2?, 13, 19 ; e = 13, 21 ; f = 5 , 19., 23 ; g = 16 ;
2
2
0
0
2
1
h=162,17,183;i=4,183;j=162,192;k=9,11?;l=8,1~,12,18;m=5;n=10;~=10,16,
2
20;p=7.
112
Bulletin, Scripps Institution of Oceanography
Comparison of Phylogenetic Hypotheses. No explicit cladogram for all
munnopsid taxa has been created in the past, so an estimate of their phylogeny
was assembled using relationships hypothesized in the literature. The resulting
cladogram is used as a hypothesis to compare with the phylogenies derived here.
To create the trees in Figure 41, these steps were followed:
1. The phylogenetic tree of Kussakin (1973) was used for a family-level
skeleton. It shows the Ilyarachnidae branching off earliest, with the
Eurycopidae and Munnopsidae as sister groups.
Wolff's (1962) subfamilies of the Eurycopidae were made sister groups
2.
arising from a single polychotomy within the eurycopid clade.
3. Hessler and Thistle (1975) said Betamorpha should be assigned to the
Eurycopidae, but indicated that this genus was transitional between the
Ilyarachnidae and the Eurycopidae. Therefore, Betamorpha was placed
branching from the first node within the Eurycopidae before the derivation
of the other subfamilies.
Figure 40. Cladogram of selected munnopsid genera. One of the trees generated using successive
weights in the program ITERMIX. It has a parsimony value of 60 unweighted steps. Character
meanings are described in text. Character changes are marked as in Figure 39. The character
changes for the terminal taxa are indicated by lower-case letters. Their meanings are as follows:
a = 213; b = 212;c = 3, 18', 21'; d = lo2, 16', 20, 232; e = 232; f = so, 19?,232; g = 13, 213; h = 1 6 ~ ;
2
2
0
7
7
2
i = 15, 1 6 ~17,
, 1 8 ~j ;= 4, 1 8 ~k; = 16 , 19 ; 1 = 5 ; m = 9, l l ' , 12.; n = 8, 10 , 12, 1 8 ~o; = 10'.
Wilson:Revision of the Lipomerinae
Figure 41. Cladograms based on hypothetical relationships derived from the literature. A,
Cladogram with unresolved clades. B, Cladogram with clades resolved using PENNY to find the
most parsimonious arrangements. Tree B requires 99 character changes using the data in Table 7.
Bulletin, Scripps Institution of Oceanography
Wilson and Hessler (1981) removed several new genera from Eurycope
without establishing their relationships to other munnopsids. These are left
as multiple sister groups of Eurycope.
Wilson and Hessler (1981) and Wilson (1982a) indicated that the genus
Baeonectes was closely related to Munnopsurus, so these two genera were
made sister groups.
Wilson and Thistle (1985) proposed that Amuletta was the sister group of
the Ilyarachnidae.
Hapsidohedra is removed from Ilyarachna in this paper. The two genera
are retained as sister groups.
Coperonus and Lionectes are removed from Eurycope in this paper; they
are included in the polychotomy of Eurycope and its sister groups.
Figure 42. A tree based on 100 bootstrap estimates using the data in Table 7. The number in each
circle indicates the frequency of the monophyletic group above each node. These frequencies are
equivalent to the percentile confidence limits for the monophyletic groups.
Wilson: Revision of the Lipomerinae
115
These interpretations resulted in the unresolved cladogram shown in figure
41A. To find a more resolved and parsimonious topology of this tree, the
polychotomous clades were analyzed with the PHYLIP program PENNY,
resulting in the tree shown in figure 41B. The homoplasy level in this tree is
high: 99 character changes are required, 2.75 times the number of steps in a one
change per character tree. This is equivalent to an overall consistency index of
0.36. The new munnopsid trees have parsimony values (59-60 unweighted
character changes) and consistency indices (0.60-0.61) that are two times better
than those based on the previous classification. Nevertheless, the character set
provided here is not sufficient to resolve all phyletic relationships between the
munnopsids, as indicated by several multiply branching nodes.
Bootstrap Confidence Limits. The PHYLIP program BOOT (Felsenstein 1985)
provides a measure of the robustness of the phylogenetic hypotheses described
by the trees in Figures 39 and 40. One hundred bootstrap runs on the unweighted
data set yielded the consensus tree shown in Figure 42, with the confidence levels
for each monophyletic clade shown at its ancestral node. None of the clades
exceed the 95% confidence level (for exact definition, see Felsenstein 1985),
although the Lipomerinae appear most frequently (89%). This result indicates
that none of clades has enough defining apomorphies to be insensitive to
reevaluation of the characters, although the Lipomerinae are nearly in that
category.
A Consensus Tree. Two runs of ITERMIX, using both weighting protocols,
generated 140 trees similar to the those illustrated in figures 39 and 40. A strict
consensus tree (Rohlf 1982) was derived using the program CONTREE. The
resulting consensus tree had to be corrected for O-length branches because
PHYLIP programs generate only fully dichotomous trees (no polychotomes).
The corrected consensus tree (Fig. 43) tree shows that the lipomerine taxa appear
together in all trees resulting from both a priori and successive weighted data.
The resolution of the remaining clades is decreased to a large polychotomy
separated by two branching nodes from Eurycope and its allies. Ilyarachna
clusters with two taxa previously thought to be closely related (Betamorpha and
Amuletta), and with Storthyngura. Other relationships are poorly resolved, and
will require more characters and more analysis.
Relationships Within the Lipomerinae
Because the subfamily Lipomerinae are reasonably well corroborated as a
monophyletic group, phylogenetic relationships within the subfamily are
evaluated. The munnopsid-level analysis indicztes that Munneurycope or
Acanthocope may be used as a sister group to the ilyarachnid-like eurycopids.
Cladograms derived using either taxon were identical. The Lipomerinae were
analyzed with the PHYLIP program PENNY, using the uropodal characters
(Table 6). The tree shown in figure 44 is found regardless of the weighting
Bulletin, Scripps Institution of Oceanography
Figure 43. Strict consensus trees of the Munnopsidae sensu lato A. Consensus tree from 56 unique,
fully bifurcating trees generated by the a priori weighting analyses. B. Consensus tree from 88
unique, fully bifurcating trees generated by the successive weighting analyses.
Wilson:Revision of the Lipornerinae
117
protocol used. This tree has a homoplasy level of 18% (3 extra steps in the 17
characters that change) and a consistency index of 0.85. The topology of this
tree is identical to that of the lipomerine clade in the consensus tree (Fig. 43).
Nevertheless, all these genera have many defining apomorphies; the reader is
referred to the diagnoses in the taxonomy section. Two clades irr the
Lipomerinae are indicated by the cladogram (fig. 44): one contains Coperonus
and Mimocopelates, and the other shows unresolved relationships between the
genera Hapsidohedra, Lipomera, and Lionectes. The bootstrap confidence limits
for these groups are so low that a formal classification for them is not warranted.
Figure 44. The cladogram of the Lipomerinae with Acanthocope as an outgroup. The tree is
constructed using the data set in Table 7 and the added uropodal characters 24 and 25 (Table 6). Its
parsimony value is 20 steps. The character changes - straight lines crossing branches - are marked
to show where homoplasy has occurred: a closed circle is a convergence, and a closed square is a
reversion that occurs in the general munnopsid cladogram. The character change marked by a
dotted line is an uncertain change.
118
Bulletin, Scripps Institution of Oceanography
DISCUSSION AND PROPOSALS FOR A REVISED CLASSIFICATION
The Lipomerinae
The ilyarachnid-like eurycopids are the best corroborated monophyletic
group within the Munnopsidae sensu lato. Their resemblance to the
Ilyarachnidae results from convergent evolution in some characters, not to
proximate common ancestry. The analysis confirms that they should be
recognized as a munnopsid subfamily, for which I have proposed the name
Lipomerinae, based on the available family name Lipomeridae Tattersall, 1905.
The defining synapomorphies of the Lipomerinae are reduction of pereonite 7,
loss or reduction of pereopod VII, and two or three setae on the exopod of
pleopod IV. This subfamily also has characters that are characteristic of a larger
subset of the munnopsids: a frontal arch, a cleft in the female pleopod, and no
rostrum. The membership of this larger group is currently uncertain owing to the
weakness of some dichotomies in the munnopsid cladogram.
The Munnopsidae and Its Subtaxa
Although definition of the Lipomerinae was the primary goal of this paper,
other conclusions may be drawn that are relevant to munnopsid systematics. The
sister group relationship between Ilyarachna and Amuletta proposed by Wilson
and Thistle (1985) cannot be rejected on the basis of this analysis. The
postulated close relationship between Baeonectes and Munnopsurus (Wilson and
Hessler 1981; Wilson 1982a), however, is rejected.
Overall, the form of the munnopsid trees (Figs. 39 and 40) imply three
large taxa, although some major branching nodes are based on homoplasic
characters, such as those of the pleopods. The strict consensus trees (Fig. 43)
show much less resolution than the cladograms in Figures 39 and 40.
Nevertheless, the consensus trees demonstrate that the currently recognized
family Eurycopidae is not monophyletic. In fact, eurycopid taxa such as
Storthyngura and Betamorpha may have more synapomorphies with the
Ilyarachnidae than they do with Eurycope. Previous classifications of the
munnopsids that retained three separate families are not consistent with the
phylogenetic consensus.
Because there are characters that define the Munnopsidae, I propose that the
family Munnopsidae be re-expanded with the Eurycopidae and Ilyarachnidae
placed within it as subfamilies. The other subfamilies of the Eurycopidae
(Acanthocopinae, Bathyopsurinae, Syneurycopinae, and Lipomerinae) retain
their current rank. This new classification for the Munnopsidae is presented in
Table 8.
A great deal of justification can be found for this scheme. Members of this
diverse family, as first recognized by Sars (1899), are united by basic swimming
modifications. The defining synapomorphies of the Munnopsidae are: pereonites
5-7 enlarged, muscular, broadly joined, with the ventral nerve cord ganglia fused
Wilson: Revision of the Lipomerinae
TABLE 8.
A revised classification of the Munnopsidae and
the subfamily Lipomerinae.
Family Munnopsidae Sars, 1869
Subfamily Munnopsinae Sars, 1869
Munnopsis Sars, 1861
Acanthomunnopsis Schultz, 1978
Munnopsoides Tattersall, 1905
Paramunnopsis Hansen, 1916
Pseudomunnopsis Hansen, 1916
Subfamily Ilyarachninae Hansen, 1916
Ilyarachna Sars, 1864
Aspidarachna Sars, 1899
Bathybadistes Hessler and Thistle, 1975
Echinozone Sars, 1899
Pseudarachna Sars, 1899
"Subfamily Acanthocopinae Wolff, 1962
Acanthocope Beddard, 1885
Subfamily Lipomerinae Tattersall, 1905
"Lipomera Tattersall, 1905
Hapsidohedra n. gen.
"Lionectes n. gen.
"Coperonus n. gen.
Mimocopelates n. gen.
"Subfamily Bathyopsurinae Wolff, 1962
Bathyopsurus Nordenstam, 1955
Paropsurus Wolff, 1962
"Subfamily Syneurycopinae Wolff, 1962
Syneurycope Hansen, 1916
Bellibos Haugsness and Hessler, 1979
"Subfamily Eurycopinae Hansen, 1916
Eurycope Sars, 1864
Baeonectes Wilson, 1982
Belonectes Wilson and Hessler, 1981
Disconectes Wilson and Hessler, 1981
Tytthocope Wilson and Hessler, 1981
lncertae Sedis
Amuletta Wilson and Thistle, 1985
"Betamorpha Hessler and Thistle, 1975
Microprotus Richardson, 1909
"Munneurycope Stephensen, 1913
"Munnopsurus Richardson, 1912
"Munnicope Menzies and George, 1972
*Storthyngura Vanhoffen, 1914
The sequencing convention for displaying phylogenetic information in the classification (Wiley
1981) is not used for the genera; after the type-genus which is listed first, they are in alphabetical
order. Subfamilies or unclassified genera marked with a "*" previously were placed in the family
Eurycopidae. All subfamilies are sedis mutabilis.
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into a single mass (Hult 1941); pereopods V-VII with many long, fully plumose
setae and their carpi and propodi broadened and paddlelike; dactylar claws that
enclose the distal sensillae in a hollow between the anterior and posterior claws;
rami of pleopod 111 with many distal plumose setae; and broadened first articles
of the antennulae. A formal diagnosis of the Munnopsidae is provided by Wilson
et al. (in press). In addition, the subfamilies of the previous classifications are as
different from one another as are the families, thereby making the hierarchical
levels within the munnopsids incommensurate. The new classification in Table 8
is more natural than previous concepts: it places the previous families on the
same level as the subfamilies, and it recognizes the basic monophyly of the
munnopsids. Several classificatory problems remain, however, which require the
incorporation of some of the previous munnopsid taxonomic structure. The
systematic position of the genera assigned to the subfamily Eurycopinae presents
the greatest problems.
The Eurycopinae and the Composition of the Subfamilies
The consensus tree of the Munnopsidae sensu lato forces a reconsideration
of the composition of the subfamily Eurycopinae. Wolff (1962) placed the
following genera in this subfamily: Eurycope, Lipomera, Munneurycope,
Munnopsurus, and Storthyngura. Several new genera have been added since his
paper, rendering the subfamily morphologically diverse. Wilson and Hessler
(1981) added the genera Disconectes, Belonectes, and Tytthocope, and Wilson
(1982a) added Baeonectes. Menzies and George (1972) ignored Wolff's
classification when they erected Munnicope, so by default, perhaps, it should be
placed in this subfamily. Microprotus Richardson, 1909 has been considered a
member of the Janiridae (Wolff 1962), even though it clearly has been derived
from an ancestor of Storthyngura (Wilson et al. in press). As proposed above,
Lipomera is assigned to the Lipomerinae Tattersall, 1905, thereby simplifying
the Eurycopinae somewhat.
Eurycope, and the genera with which it clusters (Fig. 43), lack the derived
characters seen in the remainder of the munnopsid taxa: they retain a rostrum and
lack a frontal arch (see Table 6). This presumptive monophyletic group is
primarily defined by apomorphies that independently appear elsewhere on the
tree, e.g., the pleopodal setation characters. The relationships within the group
containing Eurycope may be subject to reinterpretation with further analysis,
although Disconectes, Belonectes, and Tytthocope may form a natural taxon with
the defining apomorphy of dorsally fused pereonites 5 and 6. Nevertheless, the
strict consensus tree shows a relatively well resolved clade that includes
Eurycope. Therefore I propose that the Eurycopinae be limited to Eurycope and
the four genera with which it clusters: Baeonectes, Tytthocope, Disconectes, and
Belonectes.
The remaining genera of the Eurycopinae sensu lato are each quite
distinctive and therefore are difficult to place. Two genera included in the
Wilson: Revision of the Lipomerinae
121
analysis, Munneurycope and Munnopsurus, appear in the consensus tree at a low,
unresolved level. Munnicope may be closely related to Munnopsurus, especially
in the natasomal characters, but this has yet to be firmly established. As
mentioned above, Microprotus is probably derived from a Storthyngura-like
ancestor. Storthyngura may have some similarities to Acanthocope
(Acanthocopinae; compare, for example, S. brachycephala Birstein, 1957 and
Acanthocope curticauda Birstein, 1970). The consensus tree (Fig. 43), however,
indicates that this resemblance may be superficial. On the other hand, the
ilyarachnids, represented by Ilyarachna, are a distinctive phylogenetic unit
(Thistle and Hessler 1976) that should not be placed in the same subfamily with
the remaining genera of its consensus clade (Wilson and Thistle 1985), which
includes Storthyngura.
In view of the remaining difficulties in munnopsid systematics, this
solution for the classification of the eurycopine genera must be temporary. The
alternative, a classification based strictly on the consensus tree in figure 43,
would be misleading and unstable. Consequently, only the best corroborated
parts of the consensus tree, the Eurycopinae sensu strict0 and the Lipomerinae,
are used. The remaining eurycopine genera are incertae sedis. New subfamilies
for Munneurycope, for Munnopsurus and Munnicope, and for Storthyngura and
Microprotus are not warranted by the data used here. A final solution to this
classificatory problem awaits the revision of most of the genera listed in
subfamily incertae sedis. The need for revision is greatest in the genus
Storthyngura, which contains at least two genus-level taxa (Wilson et al. in
press).
In the new classification, the compositions of the non-eurycopine
subfamilies are retained along with the new subfamilies demoted from family
status the Munnopsinae and the Ilyarachninae. Some taxa suggested by the
consensus tree are not used. The Munnopsinae and the Syneurycopinae are
maintained as separate taxa because many autapomorphies distinguish them
(Wolff 1962; Haugsness and Hessler 1979). Generally speaking, the
Munnopsinae are light-bodied, demersal benthic to holopelagic animals with
enlarged swimming legs, and the Syneurycopinae include narrow, heavy-bodied,
benthic animals that have reduced swimming legs and natasomes. For the
classification of the ilyarachnine clade (Fig. 43), I favor Amuletta as its sister
group, but other genera in this clade of the consensus tree share the same
hierarchical level. The Ilyarachninae are separate from the remaining genera,
which are temporarily assigned to incertae sedis.
Other Hierarchies?
The existence of a family as large as the Munnopsidae with its 7+
subfamilies and 30+ genera creates a taxonomic difficulty for the classification of
the superfamily Janiroidea: the family-level taxa no longer seem coordinate, due
to the variety of morphologies they subsume. All other janiroidean families have
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characters by which genera can easily be allocated to the proper family.
Moreover, most other families have a reasonable number of genera, although
some taxa, such as Haploniscus and Ischnomesus, will be or already have been
subdivided by revisions (e.g., Lincoln 1985a, 1985b).
An 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, which
parallels that of Hult (1941), has its merits: known monophyletic groups of
families in the Janiroidea (Wilson 1985, 1987) could be recognized by a "subsuperfamily" hier,archical level. For example, the families Nannoniscidae and
Desmosomatidae have much in common (Siebenaller and Hessler 1977, 1981)
and may represent such a "sub-superfamilial" taxon. Other candidates for being
sister groups at the family level are: the Munnidae and the Santiidae (Wilson
1980b), the Paramunnidae and the Abyssianiridae (ibid.), and the Dendrotiidae
and the Haplomunnidae (Wilson 1976). Unfortunately, the higher level
relationships among the deep-sea isopod families are still poorly understood, so
such a classification cannot be attempted at this time.
The failure to resolve the relationships of the subfamilies of the
Munnopsidae sensu lato is not surprising in view of the morphological diversity
of the included taxa. Such a variety of munnopsids probably did not arise in a
short period of time. In a preliminary estimate of the phylogeny of the
Janiroidea, the Munnopsidae branch off from the other deep-sea isopods within
only a few branching nodes of their origin (Wilson 1985); other highly diverse
taxa such as the Desmosomatidae and the Nannoniscidae are derived much later.
The Munnopsidae may have had a long evolutionary history, during which they
invaded most niches in the deep-sea benthos that are open to natatory Crustacea.
APPENDIX 1
GENERAL MUNNOPSID EXTERNAL MORPHOLOGY
The morphology of a typical munnopsid, Eurycope iphthima Wilson
(1981), in lateral view with anterior to the left. This figure is provided to
illustrate some of the morphological terms defined in Appendix 2. The main
body parts are the cephalon (c); 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 (AII), 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.
APPENDIX 2
A GLOSSARY OF MORPHOLOGICAL TERMS
This glossary contains definitions of crustacean morphological terms.
Many definitions are specific to the study of isopod taxonomy, with an emphasis
on the asellote superfamily Janiroidea, but some more general definitions are
included for completeness.
Aesthetasc. A long, tubular, sensory seta having thin cuticle, found on the
antennula or antenna. Aesthetascs may have a chemosensory function, because
males generally have many more of these structures than females.
Ambulosome. The part of the thorax of munnopsid isopods that bears the
walking legs. It consists of pereonites 1-4. (See Appendix 1.)
Ambulosomite. A body segment of the ambulosome. (See Appendix 1.)
Antenna (synonym, second antenna). The second, paired, cephalic appendage.
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 Appendix 1 .)
Antennula (synonyms first antenna, antennule). The first paired cephalic
appendage. In munnopsids, it consists of a wide, flattened basal segment, two
segments of intermediate thickness, and distal annular segments of varying
lengths. The most distal segments generally bear aesthetascs. (See Appendix 1.)
Appendix masculina. An alternative name for a styletlike copulatory structure
on the male pleopod 11. This structure is not homologous to similarly named
structures found in non-isopod Eumalacostraca.
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. Consisting of two articles or segments.
Bifid. 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. An adult female with fully extended oostegites on the coxae.
In specimens from deep-sea samples, the developing embryos are often 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.
Wilson:Revision of the Lipomerinae
125
Broom seta. A sensory seta that has a distinctly articulated pedestal, and two
distal rows of long, extremely thin setules. It may be found on the antennulae or
any of the pereopods.
Carpus (synonym carpopodite). The fifth segment of a thoracic limb. See
pereopod.
Cephalic Dorsal Length. The length of 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. (See Fig. 4.)
Cephalon. The head, or anteriormost body unit. In isopods, the cephalon bears
the eyes, mouth, antennulae, antennae, and four pairs of mouthparts (mandibles,
maxillulae, maxillae, and maxillipeds). (See Appendix 1.)
Chaetotaxy. The form, number, and shapes of the setae.
Circumgnathal. Around the biting or grinding surface, as in circumgnathal
denticles.
Claw. A modified seta found on the distal segment of the walking legs that is
heavily sclerotized and has a sharp tip.
Cleaning setae. Unusual setulate setae used to clean the antennae or antennulae.
These setae are located on the distal segment of the mandibular palp.
Clypeus. An unpaired dorsal unit of the cephalon bearing the labrum medially
and the mandibular fossae laterally. The fossae articulate with the dorsal condyle
of the mandibles. (See Figs. 4, 38.)
Condyle. A heavily sclerotized projection of the mandible's dorsal surface that
articulates with the cephalon in the clypeal fossa. (See Fig. 4.)
Copulatory Male. A fully adult male. In the janiroidea isopods, the male is
identified by a sperm tube on the second pleopod's stylet, which is open at its
sharp distal tip. In some specimens at this terminal stage, the vas deferens is
visible through the cuticle connecting to the penile papilla.
Coxa. 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. They 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 (synonyms dactyl, dactylopodite). The seventh or distal segment of a
thoracic appendage, bearing one or more distal claws. See pereopod.
Denticle. A short, pointed, toothlike projection of the cuticle.
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Denticulate. Having denticles.
Denticulate seta. A generally robust seta with either a row of denticles or a
group of distal denticles.
Dorsum (plural dorsa). The dorsal surface of a body segment.
Dorsal Orifice. The distal opening of the sperm tube in the janiroidean male's
first pleopod.
Endopod (synonym endopodite). The medial or interior ramus of a crustacean
appendage. In the Isopoda, another name for a thoracic appendage (exclusive of
the coxa and basis), although more typically applied to the inner ramus of a
pleopod or a uropod.
Epimere. A lateral fold of a somite's integument dorsal to the limbs.
Sometimes called the pleurite or tergal fold.
Epipod (synonym epipodite). Laterally directed lobe (exite) of the basal
segment (coxa) of the maxilliped.
Exopod (synonym exopodite). The lateral or exterior ramus of a crustacean
basis. In the Isopoda, applied to the outer ramus of a pleopod or a uropod.
Fan seta. A specialized seta on the distal tip of the maxilliped's endite. It is
made of thin, hyaline cuticle (difficult to see) and is usually broad with many
laterally pointed lobes. In the munnopsids, 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. Leaflike.
Fossa. A ventral trough in the clypeus into which the mandible's condyle
articulates. (See Fig. 4.)
Frons. The anterior part of the cephalon bearing the clypeus. It is found
between the antennulae and antennae, and below the rostrum or vertex. (See
Figs. 4, 38.)
Frontal arch. A thickening of the cephalic frons that provides a strengthened
arch between the fossal regions of the clypeus on either side of the frons.
Generally associated with enlarged and heavily sclerotized mandibles. (See Figs.
4, 38.)
Geniculate. Kneelike, or displaying an acute angle between two segments. As
in geniculate segments 2 and 3 of the antennula.
Gnathal. Of the biting or grinding surface on the mandible.
Habitus. Appearance of the whole animal.
Wilson:Revision of the Lipomerinae
127
Hemiplumose. A modified form of the plumose seta in which setules are found
in a row on only one side.
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 row.
Indurate. Heavily sclerotized or calcified, and often rough.
Instar. A discrete stage in a growth series, delimited by successive molting.
Interantennular. Between the antennae.
Ischium (plural ischia; synonym ischiopodite). The third segment of a thoracic
appendage. See pereopod.
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. Paired projections of the male's first pleopod's dorsal
cuticle. They form a seat for the medial edge of the second pleopods, allowing
both pairs of pleopods to function together during mating or as an operculum.
Manca. In isopods and certain other Peracarida, one of the first three stages or
instars of the postmarsupial life cycle, wherein the seventh pereopod is absent or
rudimentary. In some janiroideans (e.g., Lipomera) this condition is retained in
the adult; for these taxa, the manca stage cannot be identified by an absence of
the last pereopod.
Mandible. The third cephalic appendage, and first mouthpart appendage of
isopods. 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.
Marsupium. A ventral pereonal enclosure on females for developing embryos.
It is composed of oostegites projecting medially from the coxae of the anterior
pereopods (Pereopods I-VI in the munnopsids).
Maxilla (plural maxillae, synonym second maxilla). The third paired
mouthpart and fifth cephalic appendage. In the Janiroidea, it consists of a basal
segment bearing three setose lobes.
Maxilliped. Paired appendage on the posterior and ventral edge of the cephalon.
Actually it is the first thoracic appendage, but its body somite is fused into the
cephalon, and it is modified for feeding. It consists of the following functional
parts: toxa, basis bearing a flattened and setose endite, palp with five segments
(ischium, merus, carpus, propodus, dactylus), and epipod attached laterally to the
coxa.
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Maxillula (plural maxillulae, synonyms maxillule, first maxilla). The second
mouth part and fifth cephalic appendage. In the Janiroidea, it consists of two
setose lobes: a large outer lobe armed with robust, toothlike setae; and a smaller
inner lobe with only small setae.
Merus (plural meri; synonym meropodite). The fourth segment of a thoracic
appendage. See pereopod.
Molar Process. A medial process of the mandible. In the plesiomorphic
condition, it has a broad, distal, triturating surface with circumgnathal denticles,
a posterior row of broad, setulate setae, and sensory pores on the distal surface.
(See Fig. 5H.)
Natapod. A natatory pereopod of a munnopsid janiroidean, the fifth through
seventh pereopods. (See Appendix 1.)
Natasome. The often posteriorly streamlined body section of a munnopsid
janiroidean consisting of the following body segments: heavily muscularized
pereonites 5-7, and the pleotelson. (See Appendix I.)
Natasomite. A pereonite of the natasome. (See Appendix 1.)
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.
Operculum (female pleopod[s] 11). 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 Janiroidea. In males, pleopods I and I1 lock
together to form an operculum somewhat similar to that seen in the females.
Ovigerous. Bearing developing embryos in the marsupium.
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.
Each projection has two lobes, a broad lamellar outer lobe with hairlike setae on
the inner margins and a thick inner lobe covered with many hairlike setae.
Paucisetose. Having few setae.
Pedestal seta. A spinelike seta that is raised above the dorsal surface of the body
by a pedestal-like outpocketing of the cuticle.
Penile papillae (or penes). Male cuticular projections on the posterior and
medial margin of the seventh pereonite of janiroidean isopods. 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.) (See Appendix 1.)
Wilson: Revision of the Lipomerinae
Pereonite. A segment of the pereon. (See Appendix 1.)
Pereopod. 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.
(See Appendix 1.)
Pleotelson. 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 the telson, a terminal segment bearing the
anus. Primitively, there are six pleonites; the anterior five bear ventral pleopods,
and the sixth bears the uropods. In the Janiroidea, only the first pleonite is
expressed as a free segment. (See Appendix 1.)
Pleonite. A segment of the pleotelson. (See Appendix 1.)
Pleopod. One of the five paired, biramous, ventral limbs of the pleotelson. In
unmodified form, it consists of a basal segment - the protopod - and two distal
rami called the endopod and the exopod. The rami may be biarticulate. Female
Asellota lack the first pleopods. In male Asellota, the first pleopods are present
only as 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 111-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, the pleopodal cavity is sometimes called the branchial
cavity.
Plumose seta. A featherlike 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
munnopsids, this ridge becomes very large.
Preparatory female. An adult female that has developing oostegites and is in
the instar just before the brooding condition.
Protopod (synonym protopodite). The basal segment of the pleopods and the
uropods. It consists of the fused coxa and basis of the crustacean limb.
Propodus (plural propodi). The sixth segment of a thoracic appendage. See
pereopod.
Quadrangular. Having a truncate distal margin at approximately right angles to
the lateral sides.
Ramus (plural rami). A branch of an appendage.
Bulletin, Scripps Institution of Oceanography
Receptaculi (synonym coupling hooks). Modified setae that have bulbous
recurved and denticulate tips. They are located on the medial margin of the
maxilliped's basal endite and couple with their paired counterparts so that both
maxillipeds can act as a single unit.
Recurved. Curved back on itself.
Rostrum (plural rostra). A projection of the cephalic frons that may also
include the dorsal surface of the cephalon.
Sclerotized. With thick and sometimes calcified cuticle.
Sensilla (plural sensillae). 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 of the 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, toothlike denticles.
Seta (plural setae). A cuticular process that is clearly articulated with the basal
cuticle. This structure comes in many forms. Some authors call heavily
sclerotized setae "spines," even though there are smaller counterparts of the same
form named "setae" by the same authors. "Spinose seta" or "spinelike seta" is
more accurate.
Setulate seta. 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 taking one of
two forms: 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.
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.
Wilson:Revision of the Lipomerinae
Sternite. The ventral surface of a thoracic body segment.
Subchelate. Having the 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 (synonyms protopod, protopodite). An appendage segment made of
the fused basis and coxa.
Telson. The terminal segment of a crustacean's body, bearing the anus. In most
isopods, the telson is fused to the anterior pleonite.
Tergite. The dorsal surface of a body segment.
Thoracic. Of postcephalic segments 1 through 8.
Tridentate. With three denticles.
Triturating surface. The truncate distal surface of the mandible's molar
process.
Unequally Bifid seta. A seta that is often spinelike and has a smaller thin seta or
hair just proximal to its tip. The hair has a nerve extending into the cuticle and is
probably the external expression of a sensory nerve.
Unguis (synonym claw). A modified seta on the tip of the dactylus.
Uniarticulate. With only a single segment.
Uniramous. With only a single branch.
Uropod. The terminal appendage of the body, belonging to the sixth pleonite. It
consists of a basal segment - the protopod - and two uniarticulate rami - an
endopodandanexopod.
Venter. The ventral side of the body.
Vertex. The anterior and medial margin of the cephalic dorsal surface.
Vas deferens. Male duct from the testis to the penile papilla for the passage of
sperm.
Whip seta. Similar to the unequally bifid seta, except more slender. The
sensory hair on the distal tip is long and curved.
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George Wilson