The Isopods of Abyssal Depths in the Atlantic Ocean

SUMMARY 83 

INTRODUCTION 84 

Materials and Methods 84 

Definition of the Area Sampled 

History of Previous Work 85 

The Isopods of Abyssal Depths 

LIST OF ISOPODS FROM DEPTHS GREATER THAN 2000 METERS 

BY REGION 87 

SYSTEMATICS 89 

Suborder: Gnathiidea Monod 89 

A Key to the Fourteen Described Species of Gnathiidea 

Known from Depths of 500 Meters and Greater 89 

1. Genus: Gnathia Leach 90 

1. Gnathia vemae, n.sp. 90 

2. Gnathia caeca Richardson 90 

3. Gnathia stygia (G. O. Sars) 90 

4. Gnathia albescenoides, n.sp. 92 

Suborder: Quatuordecapoda (Isopoda, sensu strictu) 92 

Tribe: Asellota 92 

A Key to the Subtribes of the Tribe Asellota 92 

A Key to the Families of the Tribe Asellota, Subtribe 

Paraselloidea 94 

Family: Haploniscidae 94 

2. Genus: Haploniscus Richardson 94 

A Key to the Species of Haploniscus 95 

5. Haploniscus bicuspis (G. O. Sars) 96 

6. Haploniscus unicornis Menzies 96 

7. Haploniscus excisus Richardson 96 

8. Haploniscus spinifer Hansen 98 

in the Atlantic Ocean 

by ROBERT J. MENZIES 

Department of Biology, University of Southern California 

85 

9. Haploniscus minutus, n.sp. 99 

10. Haploniscus spatulifrons, n.sp. 

11. Haploniscus tuberculatus, n.sp. 

12. Haploniscus tridens, n.sp. 99 

13. Haploniscus elevatus, n.sp. 99 

14. Haploniscus quadrifrons, n.sp. 

99 

99 

100 

15. Haploniscus princeps, n.sp. 101 

16. Haploniscus percavix, n.sp. 101 

17. Haploniscus tricornis, n.sp. 101 

18. Haploniscus nondescriptus, n.sp. 102 

19. Haploniscus acutus, n.sp. 103 

20. Haploniscus parallelus, n.sp. 103 

21. Haploniscus capensis, n.sp. 103 

22. Haploniscus trituberculatus, n.sp. 103 

23. Haploniscus polaris, n.sp. 105 

24. Haploniscus telus, n.sp. 105 

25. Haploniscus tricornoides, n.sp. 106 

26. Haploniscus tropicalis, n.sp. 106 

27. Haploniscus rugosus, n.sp. 106 

28. Haploniscus ovalis, n.sp. 106 

3. Genus: Antennuloniscus, n.gen. 107 

A Key to the Species of Antennuloniscus 107 

29. Antennuloniscus dimeroceras (Barnard) 107 

30. Antennuloniscus armatus, n.sp. 108 

31. Antennuloniscus rostratus, n.sp. 109 

32. Antennuloniscus ornatus, n.sp. 109 

4. Genus: Hydroniscus Hansen 109 

A Key to the Species of Hydroniscus 109 

33. Hydroniscus ornatus, n.sp. 109 

34. Hydroniscus quadrifrons, n.sp. 109 

35. Hydroniscus abyssi Hansen 110 

Family: Ischnomesidae 111 

A Key to the Genera of the Ischnomesidae 111 

5. Genus: Ischnomesus Richardson 111 

A Key to the Species of Ischnomesus 111 

36. Ischnomesus profundus Hansen 112 

37. Ischnomesus bispinosus (G. O. Sars) 112 

38. Ischnomesus armatus Hansen 113 

39. Ischnomesus caribbicus, n.sp. 113 

40. Ischnomesus simplissimus, n.sp. 113 

41. Ischnomesus multispinis, n.sp. 113 

42. Ischnomesus wolffi, n.sp. 113 

43. Ischnomesus magnificus, n.sp. 114 

44. Ischnomesus bidens, n.sp. 115 

45. Ischnomesus paucispinis, n.sp. 116 

46. Ischnomesus decemspinosus, n.sp. 117 

47. Ischnomesus elegans, n.sp. 117 

6. Genus: Haplomesus Richardson 117 

A Key to the Species of Haplomesus 117 

48. Haplomesus angustus Hansen 119 

49. Haplomesus modestus Hansen 119 

50. Haplomesus quadrispinosus (G. O. Sars) 119 

51. Haplomesus tenuispinis Hansen 119 

52. Haplomesus tropicalis, n.sp. 120 

53. Haplomesus insignis Hansen 121 

54. Haplomesus ornatus, n.sp. 121 

55. Haplomesus bifurcatus, n.sp. 121 

7. Genus: Heteromesus Richardson 121 

A Key to the Species of Heteromesus 121

80 ROBERT J. MENZIES 

56. Heteromesus longiremis Hansen 122 

57. Heteromesus bifurcatus, n.sp. 122 

58. Heteromesus granulatus Richardson 122 

59. Heteromesus spinescens Richardson 123 

60. Heteromesus similis Richardson 123 

8. Genus: Stylomesus Wolff 123 

A Key to the Species of Stylomesus 123 

61. Stylomesus inermis (Vanhoffen) 123 

62. Stylomesus granulosus, n.sp. 124 

63. Stylomesus spinulosus, n.sp. 125 

64. Stylomesus elegans, n.sp. 126 

65. Stylomesus regularis, n.sp. 126 

66. Stylomesus simplex, n.sp. 126 

67. Stylomesus productus, n.sp. 127 

68. Stylomesus simulans, n.sp. 127 

Family: Macrostylidae 127 

9. Genus: Macrostylis G. O. Sars 128 

A Key to the Species of Macrostylis 128 

69. Macrostylis truncatex, n.sp. 128 

70. Macrostylis abyssicola Hansen 129 

71. Macrostylis setifer, n.sp. 130 

72. Macrostylis hirsuticaudis, n.sp. 131 

73. Macrostylis caribbicus, n.sp. 131 

74. Macrostylis vemae, n.sp. 131 

75. Macrostylis bifurcatus, n.sp. 131 

76. A4acrostylis minutus, n.sp. 131 

77. Macrostylis bipunctatus, n.sp. 132 

Family: Nannoniscidae 133 

A Key to the Genera of Nannonisridae 1 33 

10. Genus: Nannoniscnides Hansen 133 

78. Nannoniscoides hinutus. n.sp. 133 

1 1. Genus: Nannoniscus G. O. Sars 133 

A Key to the Species of Nannoniscus 1 34 

79. Nannoniscus inermis Hansen 13 > 

80. Nannoniscus nrmatus Hansen 135 

81. Nannoniscus analis Hansen 135 

82. Nannoniscus oblongus G. O. Sars 136 

83. Nannoniscus camayae. n.sp. 137 

84. Nannoniscus laevis, n.sp. 138 

85. Nannoniscus primiticus, n.sp. 138 

86. Nannoniscus spinicornis Hansen 138 

Family: Kurycopidae 138 

A Key to the Genera of the Kurycopidae 138 

12. Genus: Eurycope G. O. Sars 139 

A Kev to the Abyssal Species of Eurycope 13'' 

87. Eurycope antarctica Vanhoffen 139 

88. Eurycope furcata G. O. Sars 140 

89. Eurycope producta G. O. Sars 141 

90. Eurycope vacarius Vanhoffen 141 

91. Eurycope complanata Bonnier 141 

92. Eurycope murrayi Walker 141 

93. Eurycope parva Bonnier 142 

94. Eurycope nodifrons Hansen 143 

95. Eurycope hanseni Ohlin 143 

96. Eurycope incisa Gurjanova 143 

97. Eurycope acutitelson, n.sp. 143 

98. Eurycope nodosa, n.sp. 145 

99. Eurycope ovaloides, n.sp. 145 

Genus: Storthyngura Vanhoffen 145 

A Key to the Species of Storthyngura 145 

100. Storthyngura digitata, n.sp. 146 

101. Storthyngura truncata (Richardson) 146 

102. Storthyngura magnispinis (Richardson) 147 

103. Storthyngura triplispinosa, n.sp. 149 

104. Storthyngura symmetrica, n.sp. 149 

105. Storthyngura vemae, n.sp. 149 

106. Storthyngura birsteini, n.sp. 149 

107. Storthyngura snanoi, n.sp. 149 

13. Genus: Syneurycope Hansen 150 

A Key to the Species of Syneurycope 151 

108. Syneurycope heezeni, n.sp. 151 

109. Syneurycope parallela Hansen 151 

110. Syneurycope hanseni Menzies 151 

111. Syneurycope multispina, n.sp. 152 

14. Genus: Acanthocope Beddard 152 

A Key to the Species of Acanthocope 153 

112. Acanthocope'argentinae, n.sp. 154 

113. Acanthocope unicornis, n.sp. 155 

114. Acanthocope annulalus, n.sp. 155 

Family: Ilyarachnidae 155 

15. Genus: Ilyarachna G. O. Sars 156 

115. Ilyarachna abyssorum Richardson 156 

116. Ilyarachna bicornis Hansen 156 

117. Ilyarachna spinosissima Hansen 157 

118. Ilyarachna longicornis G. O. Sars 157 

119. Ilyarachna derjugini Gurjanova 158 

120. Ilyarachna nodifronoides, n.sp. 158 

121. Ilyarachna qfricana, n.sp. 159 

122. Ilyarachna spinoajricana, n.sp. 160 

123. Ilyarachna simplex, n.sp. 160 

124. Ilyarachna multispinosa, n.sp. 160 

125. Ilyarachna argentinae, n.sp. 160 

126. Ilyarachna gurjanovae, n.sp. 160 

127. Ilyaiachna identijrons, n.sp. 161 

128. Ilyaiachna tiiangulaia, n.sp. 161 

129. Ilyarachna scotia, n.sp. 162 

family: Desmosomidae 162 

16. Genus: Desmosoma G. O. Sars 162 

A Key to the Species of Desmosoma 163 

130. Desmosoma giaciltpcs Hansen 163 

131. Desmosoma insigne Hansen 163 

132. Desmosoma simile Hansen 164 

133. Desmosoma intermedium Hult 165 

134. Desmosoma coarcticum (G. O. Sars) 165 

135. Desmosoma longispinum Hansen 165 

136. Desmosoma striata, n.sp. 165 

137. Desmosoma magnispinum, n.sp. 165 

138. Desmosoma birsteini, n.sp. 166 

Family: Dendrotionidae 167 

A Key to the Genera of the Dendrotionidae 167 

17. Genus: Dendromunna, n.gen. 167 

139. Dendromunna spinipes, n.sp. 167 

Family: Ianirellidae 167 

18. Genus: lanirella Bonnier 168 

A Key to the Species of lanirella 168 

140. lanirella lobata Richardson 168 

141. lanirella bifida, n.sp. 168 

142. lanirella laevis Hansen 168 

143. lanirella vemae Menzies 169 

144. lanirella magnifrons, n.sp. 169 

19. Genus: Spinianirella, n.gen. 170 

145. Spinianirella walfishensis, n.sp. 171 

20. Genus: Rhacura Richardson 171 

146. Rhacura pulchra Richardson 172

Family: Munnidae 172 

A Key to the Genera of the Munnidae 173 

21. Genus: Munna Kroyer 173 

147. Munna [Munna) acanthi/era Hansen 173 

148. Munna (Munna) argentinae, n.sp. 173 

22. Genus: Acanthomunna Beddard 174 

A Key to the Species of Acanthomunna 175 

149. Acanthomunna beddardi, n.sp. 176 

23. Genus: Notoxenoides, n.gen. 176 

150. Notoxenoides abyssi, n.sp. 177 

151. Notoxenoides vemae, n.sp. 177 

Family: Acanthaspidae, new family 177 

24. Genus: Acanthaspida Stebbing 177 

A Key to the Species of Acanthaspidia 177 

152. Acanthaspidia bifurcata, n.sp. 177 

153. Acanthaspidia decorata Hansen 178 

Family: Abyssianiridae Menzies 179 

25. Genus: Abyssianira Menzies 179 

154. Abyssianira dentifrons, Menzies 179 

155. Abyssianira argentenensis, n.sp. 179 

26. Genus: Xostylus, n.gen. 179 

156. Xostylus parallelus, n.sp. 181 

Family: Ianiridae 181 

27. Genus: Ianira Leach 181 

157. Ianira hanseni, n.sp. 181 

28. Genus: Abyssijaera, n.gen. 181 

158. Abyssijaera ocarina, n.sp. 181 

Family: Echinothambemidae Menzies 183 

29. Genus: Echinothambema Menzies 183 

159. Echinothambema ophiuroides Menzies 183 

30. Genus: Vemathambema, n.gen. 183 

160. Vemathambema elongata, n.sp. 183 

Family: Thambematidae 183 

31. Genus: Thambema Stebbing 184 

161. Thambema amicorum Stebbing 184 

Incertae Sedis 184 

32. Genus: Mesosignum, n.gen. 184 

A Key to the Species of Mesosignum 184 

162. Mesosignum kohleri, n.sp. 184 

163. Mesosignum usheri, n.sp. 185 

ABYSSAL ATLANTIC ISOPODS 81 

Tribe: Flabellifera 186 

A Key to the Flabelliferan Subtribes 186 

Family: Serolidae 186 

33. Genus: Serolis Leach 186 

164. Serolis (Serolis) neaera Beddard 186 

165. Serolis (Serolis) margaretae, n.sp. 187 

166. Serolis (Serolis) macdonnellae, n.sp. 188 

167. Serolis (Serolis) vemae, n.sp. 189 

168. Serolis (Serolis) maryannae, n.sp. 189 

34. Genus: Glabroserolis, n.gen. 189 

169. Glabroserolis specialis, n.sp. 189 

Subtribe: Anthuroidea 190 

A Key to the Genera of the Anthuroidea Having Abyssal 

Species (after Barnard) 190 

35. Genus: Pseudanthura Richardson 191 

170. Pseudanthura lateralis Richardson 191 

36. Genus: Calathura Norman and Stebbing 191 

171. Calathura brachiata (Stimpson) 191 

37. Genus: Anthelura Norman and Stebbing 192 

172. Anthelura truncata (Hansen) 192 

38. Genus: Ananthura Barnard 193 

173. Ananthura abyssorum (Norman and Stebbing) 

193 

39. Genus: Hyssura Norman and Stebbing 193 

174. Hyssura producta Norman and Stebbing 193 

40. Genus: Leptanthura G. O. Sars 193 

Subtribe: Cirolanoidea 194 

Tribe: Valvifera 194 

Family: Arcturidae 194 

41. Genus: Antarcturus zur Strassen 194 

42. Genus: Mesidothea Richardson 195 

175. Mesidothea megalura polaris Gurjanova 195 

176. Mesidothea megalura megalura (G. O. Sars) 195 

LIST OF ATLANTIC ABYSSAL BIOLOGICAL TRAWL SAMPLES OF 

THE LAMONT GEOLOGICAL OBSERVATORY 196 

LIST OF OTHER ABYSSAL ATLANTIC AND ARCTIC STATIONS FROM 

WHICH ISOPODS WERE COLLECTED 202 

BIBLIOGRAPHY 205

In this monograph 176 species are described. Prior 

to this work only 66 species were known from the 

Arctic-Atlantic below 2000 meters and only 143 were 

known from the abyss of the world oceans, excluding 

probably pelagic species. This means that the results 

of this work based upon 84 abyssal trawl samples 

taken by the R.V. Vema and M.V. Theta increase 

by roughly one-fifth the number of abyssal species 

known for the entire world in the order Isopoda. The 

number of species from the Atlantic, where the fauna 

was best known previously, is increased by over two 

times. One hundred and seven new species are 

described from the Atlantic abyss and near abyss for 

the first time. Species new to the abyss but previously 

known elsewhere, are Antennuloniscus dimeroceras 

Barnard), Stylomesus inermis (Vanhoffen), Nannoniscus 

oblongus G. O. Sars, Eurycope antarctica Vanhoffen, and 

Eurycope vicarius Vanhoffen. Additionally five species 

previously recorded from the Atlantic abyss are 

excluded from this monograph due to the fact that 

they are too poorly known. These are Eurycope 

SUMMARY 

abyssicola Beddard, Acanthocope acutispina Beddard, 

Eurycope sp., Ischnomesus bacillus Beddard, and Storthyngurafragilis 

(Beddard). The list of the new species 

is contained in the table of contents. 

A total of nine new genera is described. These are 

Antennuloniscus (formerly part Haploniscus), Dendromunna, 

Spinianirella, Notoxenoides, Xostylus, Abyssijaera, 

Mesosignum, Glabroserolis, and Vemathambema. This 

brings the known abyssal Atlantic genera to 41 when 

one adds the five genera that were previously known 

from Atlantic shallow water and are reported herein 

from the abyss, Leptanthura, Antarcturus, Acanthomunna, 

Nannoniscoides, and Stylomesus. 

Where possible analytical keys are given to the 

species (world) of each genus; partial keys are given 

to the species of Gnathia and Eurycope, and no key is 

given to the poorly defined genus Ilyarachna. 

It is intended that the zoogeographic, ecologic, and 

phylogenetic relationships of these collections will be 

subject to analytic study in the second part of this 

monograph.

In this paper the marine isopods of the abyss of the 

North and South Atlantic, including the Arctic Ocean 

and Caribbean Sea, are described. Every old and new 

species known up to 1960 is illustrated at least once. 

This study is based mainly upon the collections made 

in recent years by the research vessel belonging to the 

Lamont Geological Observatory, the R.V. Vema. 

The principal objective of this work has been to define 

abyssal communities based upon modern systematic 

studies and to determine where possible the probable 

sites of origin of these highly important abyssal 

organisms from their morphologic affinities and geographic 

distribution. Additionally, however, a study 

has been made on the food of the abyssal isopods 

through dissection and study of their gut content. 

Records were maintained also regarding the weight, 

size, state of sexual maturity, and brood size. 

The collections on which this study was based 

come from Vema cruises 7 to 15 inclusive. These 

cruises were supported by grants from the Office of 

Naval Research, the Bureau of Ships of the U.S. 

Navy, and the National Science Foundation, as part 

of the International Geophysical Year. The laboratory 

work has been supported by a grant from the Rockefeller 

Foundation and the National Science Foundation. 

The aid of the following chief scientists is particularly 

appreciated: Dr. J. Lamar Worzel, Vema 7 

and 15; Dr. Bruce C. Heezen, Vema 10; Mr. Walter 

Beckman and Captain Valvin Sinclair, Vema 12; 

Captain H. Kohler, Vema 14; Dr. Jack Nafe, Dr. 

Charles Drake, and Professor Maurice Ewing, 

Vema 14 and 15. The aid of the following shipboard 

biologists on various cruises is especially appreciated: 

Mr. Peter Trurnit, Mr. Thomas Dow, and Mr. 

Arthur Clarke, Jr. 

Discussions at various times with Professor Maurice 

Ewing, Dr. William Donn, Dr. Bruce Heezen, and 

Mr. David B. Ericson, all of the Lamont staff, have 

been particularly helpful in this work. 

The illustrations were made in pencil from projected 

images of the animals. Parts requiring higher 

magnificaton were drawn with the aid of a camera 

lucida. Penciled sketches were "inked in" by Mr. 

Donald Robinson and by myself. Previously described 

species were painstakingly copied from the publications 

involved by Mr. Donald Robinson. Sorting of 

the preserved samples was done by Mr. Thomas Dow, 

Mr. Michael Tinker, and myself. 

INTRODUCTION 

MATERIALS AND METHODS 

The material examined came from deep sea trawl 

samples. Various trawl designs were tried: first, 

the epibenthic trawl developed by Mr. Robert Bieri 

(in Hedgpeth, 1957, p. 77, Fig. 10) and, second, a 

large biology trawl (LBT), which was discarded in 

favor of a small biology trawl (SBT) designed at the 

suggestion of Mr. Walter Beckman of the Lamont 

Geological Observatory. The LBT had an opening 

one meter square, but otherwise was identical with 

the SBT. The latter has an orifice one meter wide 

by ten centimeters high and a steel frame. Attached 

to the frame is a tapered nylon net three meters long 

with a mesh diameter of 0.5 millimeters. A bridle of 

chain is attached to the front, at the yolk of which a 

eighty-pound lead weight is attached (Fig. 1). The 

bridle is attached with swivels at each joint, allowing 

the trawl and weight to wind or unwind freely as tension 

is released or increased. The cod end of the net 

is tied to the frame to prevent it from tangling around 

the trawl wire. The trawl wire was 5/32-inch hydrographic 

wire, and trawling operations were carried 

out with tensions nearing the breaking point. For 

this reason a heavier or larger trawl could not be used 

from wire of such small diameter. The SBT under 

normal conditions could be lowered and retrieved at 

maximum winch speed. This is a highly important 

disideratum of shipboard operations. 

The trawl samples when retrieved on the deck of the 

ship were put into suitable containers and preserved 

with 10 percent neutral formalin sea water buffered 

with Hexamine. 1 The entire sample, usually consisting 

of a quart of sediment and animals, was then 

sorted in the laboratory with the binocular steroscopic 

microscope. Identified specimens are transferred into 

70 percent alcohol. 

The dissection of isopod specimens generally was 

done with the aid of a microscope while the specimens 

were immersed in glycerine on a microscope slide. 

Measurements were made with a calibrated ocular 

micrometer. The weight of specimens was determined 

from wet specimens which had been damp-dried 

with a paper towel after removal from the alcohol 

preservative. Food content analyses were usually 

made on material removed from the hind gut or gastric 

1 Trade name for hexamethylenamine (USP), available 

from the Amend Drug and Chemical Co. in New York.

SWIVEL 

WEIGHT 


Figure 1. Small biology trawl (SBT) used in the majority of the Lamont collections from 

aboard Vema, frame length 3 meters, width 1 meter, diameter of orifice 10 centimeters. 

mill, and in this way an uncontaminated sample was 

obtained. 

Identified specimens were placed in cotton-stoppered 

vials in quart alcohol-filled jars. Entry in the 

catalogue provided each lot of a species from each 

trawl station from each cruise with a separate L.G.O. 

(Lamont Geological Observatory) catalogue number 

(cat. no.). Individual cruise biology trawl stations 

have been numbered consecutively (L.G.O. Biotrawl 

No.). 

DEFINITION OF THE AREA SAMPLED 

In this study the abyssal isopods of the Arctic 

Ocean, the North and South Atlantic, and the 

Caribbean are described and studied. The zoogeographical 

implications will be discussed separately as a 

significant second part of this monograph by Dr. 

Bruce C. Heezen and myself. Therefore, in this, the 

systematic part, details of zoogeography are purposely 

avoided. 

The abyssal stations on which this study has been 

based are compiled in a separate section, "List of 

Stations"; accordingly, it has been possible to give 

with each species a minimum of station detail, and 

only the L.G.O. Biotrawl number and number of 

specimens are listed. 

HISTORY OF PREVIOUS WORK 

For a general review of oceanographic expeditions 

up to 1926, the reader is referred to Schott's Geographie 

des Atlantischen Ozeans (1926). 

The first capture of abyssal isopods resulted from 

the cruises'of the Lightning (1868), Porcupine (1869— 

1870), and Valorous (c. 1870). These were reported on 

by Norman and Stebbing (1886), three species, and 

by Stebbing (1913), one species. Next came Beddard's 

great work (1884-1886, 1886) on the Challenger 

(1872-1876) collections. Beddard reported on around 

58 species, but only about 24 of these were from below 

2000 meters depth. Richardson (1909, etc.) and


Hansen (1897) reported on the abyssal isopods 

collected by the American Albatross cruises (1898- 

1913). The results of the Travailleur and Talisman 

(1880-1883) were treated by Richardson (1911), who 

also worked on the isopods collected by the Princess 

Alice 1-2 (1885-1914). The single most important 

work for the Atlantic is the monumental monograph 

by Hansen (1916) on the Danish Ingolf (1895-1896) 

and Thor (1904-1910) expeditions. Hansen treated 

164 species in that work, but only 38 were from depths 

of 2000 meters or more. The Swedish Albatross 

(1947-1948) has added only one additional abyssal 

species (Nordenstam, 1955). The principal results of 

the Danish Galathea Atlantic collections are not yet 

available. The Pacific hadal isopods of the Galathea 

have been recorded by Wolff (1956). Some of the ultra 

abyssal isopods collected by the Vitjaz (1949-date) 

have been published by Birstein (1957,1960). Several 

abyssal Atlantic species from the Vema 7 cruise (1955) 

were reported by Menzies (1956). Abyssal Arctic 

polar isopods gathered by the U.S.S.R. have been 

published most recently by Gurjanova (1946a). 

The abyssal isopods of the Antarctic have been reported 

only by Vanhoffen (1914), based on the German 

South Polar Expedition of the Gauss (1901-1903). 

A reasonably complete listing of all known benthic 

abyssal isopods is given in the following tabulation. 

Pelagic species are purposely excluded from the 

enumeration and are listed separately. 

To date 69 abyssal benthic isopods have been 

described from the Atlantic Ocean, and each of these 

is treated in this work in addition to the 107 new 

species which are herein described. In this monograph 

only benthic species from depths of 2000 or 

more meters are described except when in unusual 

circumstances a species from shallower depth is 

considered.

LIST OF ISOPODS FROM DEPTHS GREATER THAN 

Species 

ARCTIC OCEAN: POLAR BASIN 

1. Ilyarachna derjugini Gurjanova 

2. Eurycope hanseni Ohlin, Gurjanova 

3. Eurycope incisa Gurjanova 

4. Mesidothea megalura polaris Gurjanova 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

21. 

22. 

23. 

24. 

25. 

26. 

27. 

28. 

29. 

30. 

31. 

32. 

33. 

34. 

35. 

36. 

37. 

38. 

39. 

40. 

41. 

42. 

43. 

44. 

45. 

NORTH ATLANTIC OCEAN 

Abyssianira dentifrons Menzies, 1956a 5104-5122 

Acanthaspidia decorata Hansen, Nierstrasz, 

1941 4000 

Ananthura abyssorum (Norman and 

Stebbing), 1886 3199 

Anthelura truncata (Hansen), 1916 2258-2702 

Calathura brachiata (Stimpson), Hansen, 1916 18-2488 

Desmosoma coarctatum Hansen, 1916 24-2702 

Desmosoma gracilipes Hajnsen, 1916 2258-2702 

Desmosoma insigne Hansen, 1916 2702 

Desmosoma intermedium Hult, 1941 30-2258 

Desmosoma longispinum Hansen, 1916 3521 

Desmosoma simile Hansen, 1916 2258 

Echinothambema ophiuroides Menzies, 1956a 5104-5122 

Eurycope abyssicola Beddard, 1886b (insufficient 

data available on the species) 3977 

Eurycope complanata Bonnier, 1896 950-2702 

Eurycope furcata G. O. Sars, Hansen, 1916 150-2258 

Eurycope hanseni Ohlin, Hansen, 1916 460-2669 

Eurycope murrayi Walker, Hansen, 1916 1300-2775 

Eurycope nodifrons Hansen, 1916 2702 

Eurycope parva Bonnier, Hansen, 1916 872-2702 

Eurycope producta G. O. Sars, Hansen, 1916 72-2087 

Gnathia caeca Richardson 2638 

Gnathia stygia (G. O. Sars) 552-2465 

Haplomesus angustus Hansen, 1916 1373-2137 

Haplomesus insignis Hansen, 1916 698-2702 

Haplomesus quadrispinosus G. O. Sars, 

2000 METERS—BY REGION 

Hansen, 1916 510-2702 

Haplomesus modestus Hansen, 1916 2258 

Haplomesus tenuispinis Hansen, 1916 2258-3474 

Haploniscus bicuspis (G. O. Sars) Hansen, 

1916 360-2465 

Haploniscus excisus Richardson, 1908a 3235 

Haploniscus spinifer Hansen, 1916 2970-4061 

Haploniscus unicornis Menzies, 1956a 5104-5122 

Heteromesus granulatus Richardson, 1908a 713-3235 

Heteromesus longiremis Hansen, 1916 698-2707 

Heteromesus similis Richardson, 1911 2995 

Heteromesus spinescens Richardson, 1908a 2155-3337 

Hydronisus abyssi Hansen, 1916 3521 

Hyssura producta Norman and Stebbing, 

1886 ' 2651 

Ianirella laevis Hansen, 1916 2258-2702 

Ianirella lobata Richardson, 1908a 2480-3235 

Ianirella vemae Menzies, 1956a 5104-5122 

Ilyarachna abyssorum Richardson, 1911 4060-4165 

Depth Range 46. Ilyarachna bicornis Hansen, 1916 2702 

(meters) 47. Ilyarachna longicornis G. O. Sars, Hansen, 

1916 18-2788 

48. Ilyarachna spinosissima Hansen, 1916 2702-3521 

2500 49. Ischnomesus armatus Hansen, 1916 2702 

460-2500 50. Ischnomesus profundus Hansen, 1916 3521 

2380 51. Macrostylis abyssicola Hansen, 1916 3229-3521 

1300-2500 52. Mesidothea megalura megalura G. O. Sars, 

Hansen, 1916 1996-2465 

53. Munna acanthifera Hansen, 1916 552-2258 

54. Nannoniscus analis Hansen, 1916 2258 

55. Nannoniscus armatus Hansen, 1916 3521 

56. Nannoniscus inermis Hansen, 1916 2258 

57. Nannoniscus spinicornis Hansen, 1916 2465 

58. Rhacura pulchra Richardson, 1908a 3235 

59. Storthyngura magnispinis (Richardson), 

1908b 2258-2702 

60. Storthyngura truncata (Richardson), 1908b 2788-3235 

61. Syneurycope hanseni Menzies, 1956a 5104-5122 

62. Syneurycope parallela Hansen, 1916 3474 

63. Thambema amicorum Stebbing, 1913 2486 

SOUTH ATLANTIC OCEAN 

64. Eurycope murrayi Walker, Hansen, 1916 2-< 2 700 

65. Pseudanthura lateralis Richardson, 1911 930-3200 

66. Serolis neaera Beddard, 1886a 1097-3731 

MEDITERRANEAN 

No abyssal species recorded 

NORTH PACIFIC 

67. Acanthocope intermedia Beddard, 1886a 5670 

68. Arcturus parvus Richardson, 1910 2272 

69. Eurycope scabra Hansen, 1897 2486 

70. Eurycope spinifrons Gurjanova, Nierstrasz, 

1941 308-3000 

71. Gnathia elongata Hansen, 1916, Nierstrasz 120-3000 

72. Haplomesus quadrispinosus G. O. Sars, Birstein, 

1960 4000-4150 

73. Haplomunna coeca Richardson, 1905 3993 

74. Heteromesus thomsoni (Beddard), 1886 3750 

75. Ischnomesus andriashevi Birstein, 1960 4000-6560 

76. Macrostylis latifrons Beddard, 1886 3749 

77. Microthambema tenuis Birstein, 1961 5680-5690 

78. Storthyngura pulchra (Hansen), 1897 2490-2690 

79. Storthyngura chelata Birstein, 1957 5345-6860 

80. Storthyngura bicornis Birstein, 1957 6156-6207 

81. Storthyngura vitjazi Birstein, 1957 7305-8430 

82. Storthyngura herculea Birstein, 1957 6475-8100 

83. Storthyngura brachycephala Birstein, 1957 5670-5680 

84. Storthyngura tenuispinis kurilica Birstein, 1957 7210-7230 

85. Storthyngura tenuispinis tenuispinis Birstein, 

1957 7246 

86. Acanthomunna proteus Beddard, 1886 1281-2011 

87. Antarcturus abyssicola (Beddard), 1886 2560-4321 

88. Acanthocope acutispina Beddard, 1886a 2650 

89. Naesicopea abyssorum (Beddard), 1886a 1958


90. Eurycope galatheae Wolff, 1956 

91. Eurycope madseni Wolff, 1956 

92. Eurycope nodifrons Hansen, Wolff, 1956 

93. Haploniscus robinsoni Menzies and Tinker, 

1960 

94. Ianira abyssicola Beddard, 1886 

95. Ischnomesus bacilloides (Beddard), 1886a 

96. Stylomesus wolffi Birstein, 1960 

97. Stylomesus pacificus Birstein, 1960 

98. Stylomesus gracilis Birstein, 1960 

99. Stylomesus menziesi Birstein, 1960 

100. Heteromesus gigas (Birstein), 1960 

101. Heteromesus scabriusculus (Birstein), 1960 

102. Heteromesus robustus (Birstein), 1960 

103. Haplomesus brevispinis Birstein, 1960 

104. Haplomesus cornutus Birstein, 1960 

105. Haplomesus orientalis Birstein, 1960 

106. 

107. 

108. 

109. 

110. 

111. 

112. 

113. 

114. 

115. 

116. 

117. 

118. 

119. 

120. 

121. 

122. 

123. 

124. 

SOUTH PACIFIC 

Ischnomesus bruuni Wolff, 1956 

Ischnomesus spdrcki Wolff, 1956 

Leptanthura hendili Wolff, 1956 

Macrostylis galatheae Wolff, 1956 

Macrostylis hadalis Wolff, 1956 

Storthyngura benti Wolff, 1956 

Storthyngura furcata Wolff, 1956 

Storthyngura novae zelandiae (Beddard), 1886a 

Storthyngura pulchra Hansen, Wolff, 1956 

Acanthocope spinicauda Beddard, 1886a 

Antarcturus abyssicola (Beddard), 1886a 

Antarcturus brunneus (Beddard), 1886a 

Antarcturus spinosus (Beddard), 1886a 

Eurycope sp. Beddard, 1886a 

Eurycope sarsii Beddard, 1886a 

Eurycope spinosa Beddard, 1886a 

Ischnomesus bacillus (Beddard), 1886a 

Serolis antarctica Beddard, 1884 

Serolis bromleyana Suhm, Beddard, 1884 

INDIAN OCEAN 

125. Antarcturus furcatus (Studer), 1914 

126. Antarcturus gaussianus Vanhoffen, 1914 

127. Antarcturus glacialis (Beddard), 1886a 

128. Desmosoma longimana Vanhoffen, 1914 

129. Eurycope ovalis Vanhoffen, 1914 

130. Eurycope vicarius Vanhoffen, 1914 

131. Haploniscus antarcticus Vanhoffen, 1914 

132. Haploniscus curvirostris Vanhoffen, 1914 

133. Iolanthe acanthonotus Beddard, 1886a 

6960-7000 

6960-7000 

6960-7000 

2860-2858 

2468 

2652 

4000-5530 

5450 

5680-5690 

5680-5690 

6560-8430 

5450 

5450-5817 

5510-5690 

6471-6571 

4000-4150 

6960-7000 

6660-7000 

6580 

9820-10,000 

7270 

5230-7000 

5850-6770 

2012 

6620 

3290 

2560-4359 

2928 

2516 

2925 

2514-2926 

3565 

3292 

2517-2925 

1280-2011 

3062 

2450 

3062 

2735 

3423 

3423 

385-3397 

3423 

3062 

134. Ilyarachna antarctica Vanhoffen, 1914 

135. Janthopsis nodosus Vanhoffen, 1914 (and 

65° 42' S., 79° 49' E.) 

ANTARCTIC 

136. Microprotus antarcticus Vanhoffen, 1914 

137. Serolis bromleyana Suhm, Beddard, 1884 

138. Serolis johnstoni Hale 

139. Serolis meridionalis Hodgson, Vanhoffen, 

1914 

140. Stenetrium acutum Vanhoffen, 1914 

141. Storthyngura elegans Vanhoffen, 1914 

142. Storthyngurafragilis (Beddard), 1886 

143. Stylomesus inermis (Vanhoffen), 1914 

252-3423 

3423 

3398 

3612 

2267 

2725 

385-3397 

3423 

?2303 

2450 

EXCLUDED PROBABLE PELAGICS: NORTH ATLANTIC 

1. Asconiscus simplex G. O. Sars, Vanhoffen, 

1914 0-3000 

2. Bathyopsurus nybelini Nordenstam, 1956 5500-7900 

3. Cumoechus insignis Hansen, 1916 806-2465 

4. Eurydyce grimaldi Dollfuss, Stephensen, 1915 0-2600 

5. Eurydyce stygia G. O. Sars, Hansen, 1916 2465 

6. Holophryxus acanthophyrae Stephensen, 1913

The systematic arrangement of this monograph follows 

the scheme set forth by Menzies (in press). In outline 

this is: 

Order: Isopoda 

Suborder: Gnathiidea 

Suborder: Quatuordecapoda (Isopoda, sensu stricto) 

Tribe 1: Asellota 

Tribe 2: Valvifera 

SYSTEMATIGS 

Tribe 3: Flabellifera 

Tribe 4: Epicaridea 

Tribe 5: Oniscoidea 

Tribe 6: Phreatoicidea 

The Phreatoicidea and Oniscoidea, with terrestrial 

and fresh water species, lack abyssal representatives 

and are, therefore, outside of the scope of this 

work. 

Suborder: GNATHIIDEA MONOD, 1926a 

This major category of the Isopoda deserves mention 

in a treatise on abyssal organisms mainly because 

it is so poorly represented in the abyss. Only two 

species are known from below 2000 meters; these are 

Gnathia stygia (G. O. Sars) and Gnathia caeca Richardson. 

The majority of the species live in shelf depths 

(viz., down to 200 meters). The animals, by virtue 

of their parasitic mode of life, are intimately tied to a 

fish host. This is probably the major reason why 

they have not been successful in penetration of the 

deep sea. 

The main zoogeographic conclusions that can be 

drawn from the great work by Monod (1926a) are 

that the gnathiid isopods are cosmopolitan in their 

distribution; that there are more species in the north 

and south temperate zones than elsewhere; and that 

the Antarctic has three times the number of species 

found in the Arctic. Bipolarity is not known in this 

group. 

Diagnosis: Isopoda with five pairs of peraeopods. 

Mandibles of male project beyond cephalon as a pair 

of pincers. Last pair of appendages lost and seventh 

somite much reduced. Appendages of first peraeonal 

somite united into the cephalon as a second pair of 

maxillipeds (the pylopods). Adult male is the gnathia 

stage, adult female the praniza, and larval form the 

anceus. 

Affinities: The gnathiidea have obviously been 

derived from a cirolanid-type ancestor, and as early 

as the Jurassic the probable precursor Urda was 

developed. The nearest relative to Urda living today, 

however, is probably Gnatholana, a shallow water 

genus from Africa. 

I tend to favor the consideration that the gnathiids 

represent a group which has evolved since the Mesozoic 

from an Urda-like ancestor. Since then they have 

become highly specialized fish parasites. Gnatholana, 

on the other hand, probably represents a relict 

descendant from the Urda type. 

Two new species of Gnathia were found in the 

Vema collections from bathyal depths off the South 

African coast. These are described here together with 

the only two known abyssal species, G. stygia and 

G. caeca. 

A KEY TO THE FOURTEEN DESCRIBED 

SPECIES OF GNATHIIDEA KNOWN FROM 

DEPTHS OF 500 METERS AND GREATER 

(Modified from Monod, 1926a, pp. 282-339) 

1. Pylopods with five articles 2 

1. Pylopods with three articles 5 

2. Frons produced as a triangulate process as far as 

the apex of the mandibles . Bathygnathia ... 3 

2. Frons not produced . . . . Akidognathia ... 4 

3. Apex of rostrum with a 

patch of setae bathybia (Beddard) 

(1638 meters, Challenger, 38° 11' N., 27° 9' W.) 

3. Apex of rostrum nude . . . . curvirostris Richardson 

(709-1232 meters, Albatross, N. Atlantic, south of 

Martha's Vineyard and east of Georges Bank) 

4. Pylopods operculate cristatipes (Stebbing) 

(980 meters, Porcupine, 48° 6' N., 9° 18' W.) 

4. Pylopods pediform poteriophora Monod 

(914 meters, Ingolf, St. Croix, Antilles) 

5. Frons produced 7 

5. Frons not produced 6 

6. Frontal process bifid abyssorum (G. O. Sars) 

(N. Atlantic, Norwegian fjords, 128-887 meters) 

6. Frontal process trifid oxyuraea (Lilljeborg) 

(Norway, England, Mediterranean, 0-533 meters) 

7. With eyes 8 

7. Without eyes 11 

8. Eyes produced on immovable 

swellings elongata (Kreyer) 

(0-890 meters, circumpolar, Norway, etc.) 

8. Eyes not produced, sessile 9 

9. Supraocular lobe produced . . . hirsuta (G. O. Sars) 

(208-1755 meters, Norway, Davis Strait) 

9. Supraocular lobe not produced 10

90 

ROBERT J. MRNZIES 

10. Head subcircular, mandibles small and not 

extending to margin of frons . . . serrata Richardson 

(709 meters, Albatross, N. Atlantic, south of Martha's 

Vineyard) 

10. Head quadrate, mandibles 

normal tuberculata Richardson 

(1132 meters, Albatross, 37° 22'.30" N., 137° 47' E., 

off Japan) 

11. Peraeopods strongly spinous, head small 

(much narrower than peraeon) . . stygia (G. O. Sars) 

(535-2391 meters, N. Atlantic) 

11. Peraeopods weakly spinous, head large (nearly as 

wide as peraeon) 12 

12. Somite 4 of peraeon with a sulcus on 

dorsal suface at midline caeca Richardson 

(2638 meters, N. Atlantic) 

12. Somite 4 of peraeon without a sulcus on dorsal 

surface at midline 13 

13. Lateral border of head strongly convex. 

Lateral margin of peraeon convex . . bicolor Hansen 

(1537 meters, N. Atlantic) 

13. Lateral border of head scarcely convex, borders 

of peraeon subparallel albescens Hansen 

(842-1018 meters, N. Atlantic) 

Genus: GNATHIA Leach 

Gnathia vemae, new species 

Figure 2 

Figure 2. Gnathia vemae, n. sp. A: male holotype; 

B: mandible and frons; C: pleotelson 

and uropod; D: pylopod; E: frons of praniza; 

F: first antenna, male. 

Synonyms: None. 

Diagnosis: Gnathia with a produced and entire 

frons, eyes lacking. Mandible with a pronounced 

redan and three teeth. Pylopod with three articles, 

last article minute. Flagellum of first antenna with 

five articles, second also with five articles. Last two 

large peraeonal somites with a dorsal medial sulcus. 

Peraeopods not markedly spinous. Pleopoda lacking 

setae. 

Measurements: Holotype male length 2.8 mm.. 

width pleotelson 0.2 mm. 

Type locality: South Atlantic, L.G.O. Biotrawl No. 

55, type plus two male paratypes and one praniza. 

cat. no. 1-41. 

Distribution: Known only from the type locality. 

Affinities: This species is closely allied to Gnathia 

caeca Richardson, from which it differs in having teeth 

on the mandible; otherwise the two are very similar. 

Gnathia caeca Richardson 

Figure 3 A-B 

Synonyms: Gnathia caeca Richardson, 1911, pp. 

519-520; Stephensen, 1915, p. 7; Monod, 1926a, 

pp. 406-408. 

Diagnosis: Pylopods with three articles. Head as 

wide as thorax. Eyes lacking. Frons produced but 

not as far as mandible apex. Supraocular lobes 

strongly tuberculate. Peraeopods without many stout 

spines. Fourth peraeonal somite with a pronounced 

dorso-medial sulcus. Margins of uropods and telson 

entire, without teeth. 

Measurements: Length 5 mm. (Monod, op. cit., 

p. 407). 

Type locality: North Atlantic, Talisman Station 76, 

latitude 25° 1' N., longitude 19° 15' W., 2638 meters 

(Monod, op. cit., p. 408). 

Distribution: Known only from type locality. 

Affinities: The species appears to be most nearly 

related to G. bicolor Hansen in key characteristics at 

least [vide Monod, op. cit., p. 332). 

Gnathia stygia (G. O. Sars) 

Figure 3 C-E 

Synonyms: Anceus stygius G. O. Sars, 1877, p. 

348; — 1885, pp. 85-92; — 1886, pp. 27, 85. Gnathia 

stygius (G. O. Sars), Stebbing, 1893, p. 338; —Ohlin, 

1901, p. 22, Fig. 3. Caecognathia stygia (G. O. Sars), 

Dollfus, 1901, p. 244. Caecognathia sarsi A. Dollfus, 

1901, pp. 244-245, Fig. 3. Bathygnathia stygia (err. 

typ.), Stephensen, 1915, p. 6. Caecognathia stygia 

(G. O. Sars), Stephensen, 1915, p. 7. Gnathia Stygia 

(G. O. Sars), Hansen. 1916, pp. 230-232; Monod, 

1926a, pp. 398-405. 

Diagnosis: Pylopods with three articles. Head 

narrower than thorax. Eyes lacking. Frons produced

ABYSSAL ATLANTIC ISOPODS 

Figure 3. A-B: Gnathia caeca Richardson. A: male; B: pylopod (after Monod, 1926a, p. 406, 

Fig. 162). C-E: Gnathia stygia (G. O. Sars). C: pleotelson; D: fifth peraeopod; E: male 

(after Monod, 1926a, pp. 400-401, Figs. 159-160). F-H: Gnathia albescenoides, n. sp. F: male 

holotype; G: pylopod; H: first antenna. 

but not as far as the mandible apex. Supraocular 

lobes ramose. Peraeopods with many stout spines. 

Fourth peraeonal somite with a pronounced dorsomedial 

sulcus. Margin of uropods and telson dentate. 

Pleopoda elongate and smooth. Entire body provided 

with sharp tubercles. Flagellum of first antenna with 

five articles. That of second antenna with seven 

articles. 

Measurements: Length to 11 mm. (Monod, op. cit., 

p. 402). 

Type locality; North Atlantic, latitude 65° 53' N., 

longitude 7° 18' W., 2127 meters. 

Distribution: Arctic Ocean (Gurjanova) to Norwegian 

Basin of North Atlantic, 552-2465 meters 

'Hansen, op. cit). Taken by the Ingolf from the 

following stations: 

North of the Faeroes: Station 141, latitude 

63° 22' N., longitude 6° 58' W., 1279 meters, temperature 

—0.6°, six specimens (five male); Station 139. 

East of Iceland: Station 105, latitude 65° 34' N., 

longitude 7° 31' W., 1435 meters, temperature —0.8°, 

one specimen (male). Station 103, latitude 66° 23' N., 


one specimen (male); Station 102, latitude 66° 23' N., 


five specimens (one male). 

North of Iceland: Station 126, latitude 67° 19' N., 


one specimen (larva); Station 124, latitude 67°40'N., 


one and one-half specimens (male). 

North east of Iceland: Station 120, latitude 

67°29'N., longitude 11° 32' W., 1666 meters, temperature 

— 1.0°, two specimens (male); Station 119, 

latitude 67° 53' N., longitude 10° 19' W., 1902 meters, 

temperature — 1.0°, one specimen (larva). 

South of Jan Mayen: Station 117, latitude69° 13' N., 

longitude 8° 23'W., 1889 meters, temperature —1.0. 

91

92 

two specimens (both larvae, one of them on Liparis 

frigidus); Station 113, latitude 69°31'N., longitude 

7° 06' W., 2465 meters, temperature — 1.0°, one 

specimen (larva, taken on Liparis frigidus). 

Gnathia albescenoides, new species 

Figure 3 F-H 


Diagnosis: Gnathia with produced frons, eyes 

lacking. Mandible with slight redan but lacking teeth 

on cutting edge. Pylopod triarticulate, last article 

minute. Last two large peraeonal somites without a 

It is possible to divide the Asellota into three groups 

of equivalent rank, as shown in the following key. 

The characteristics used are shown in Figure 4. 

A KEY TO THE SUBTRIBES OF THE 

TRIBE ASELLOTA 

(After Menzies, in press) 

1. Male first pair of pleopods fused along midline; 

consisting of an elongate sympod, lacking rami. 

Second male pleopods coupled loosely with first 

pairs. First pair of female pleopods lacking; second 

fused along midline to form a large operculum 

covering the remaining pleopods. Pleon with one 

or two somites Paraselloidea 

1. Male first pair of pleopods consist of a short 

sympod and a short ramus, neither coupled with 

second pair. First pair of pleopods of female not 

covering the remaining pleopods. Pleon with three 

somites Stenetrioidea 

1. Basal article of male first pleopods free, not joined 

medially into a single piece. Neither the first pair 

of pleopods of female nor the basal article of male 

first pleopods fused together Aselloidea 

It is perhaps well to add also that the Paraselloidea 

(Fig. 4) never have more than two somites comprising 

the pleon, whereas the Aselloidea and Stenetrioidea 

always have more than two complete pleonal somites. 

The structure of the pleon and pleopods shows 

definitely that the Paraselloidea represent a specialized 

advanced group, whereas the Stenetrioidea and Aselloidea 

conserve the greatest number of primitive 

characteristics. The Aselloidea contain only fresh 

ROBERT J. MENZIES 

dorsal medial sulcus. Flagellum of first antenna with 

five articles, second with six articles. 

Measurements: Holotype male length 5.4 mm., 

width pleon 0.4 mm., allotype length 5.5 mm., 

width pleon 0.5 mm. 

Type locality: South Atlantic, L.G.O. Biotrawl 

No. "54, types plus five male paratypes, cat. no. 1-42. 


Affinities: This species is closely allied to Gnathia 

albescens H. J. Hansen. It differs from that species 

in having a narrower frons and in having six instead 

of eight articles to the flagellum of the second antenna. 

Otherwise the two are very similar. 

Suborder : QUATUORDECAPODA (Isopoda, sensu stricto) 

The quatuordecapods contain the majority of 

the abyssal isopods, but even here the abundance of 

abyssal species is strongly skewed toward the Asellota. 

The generally detritus-feeding habits of asellotes and 

the low incidence of parasitism (none known), 

commensalism [Caecijera horvathi, Iais spp., Antias 

Tribe: ASELLOTA 

unirameus), and carnivorous feeding (none known) 

are probably the most important factors related to the 

ability of the asellotes to penetrate the abyss. Parasitic 

isopods in general are rare in the abyss. The anthurids 

perhaps constitute an exception. 

water species, whereas the Stenetrioidea are exclusively 

marine, most extensively developed in the 

shallow water of the subtropics, and have only one 

abyssal representative. To the Paraselloidea belongs 

the majority of the abyssal species It is possible to 

divide the Paraselloidea into two additional previously 

unrecognized groups. The first category embraces 

species in which the anal opening is separated 

from the branchial cavity, and the second includes 

species in which the anus is enclosed within the 

branchial cavity. As obvious as this characteristic is 

in some genera (viz., separated from the branchial 

chamber in Haploniscus, and contained within the 

branchial chamber in Pleurogonium), it is nevertheless 

impossible to utilize it at this date, due to the fact that 

it is not well enough described for the majority of 

asellote genera. At first I thought there might be a 

correlation between the separation of the anus from 

the branchial chamber and abyssal habitat, but this 

turns out not to be the case because in Abyssijaera, 

a genus in which the anus is enclosed within the 

branchial chamber, an abyssal habitat is typical, 

whereas in Munna, an intertidal genus, the anus is 

terminal and separated from the branchial chamber. 

A separation of families in the number of pleonites 

comprising the pleon is a more hopeful one, but here 

again only in those cases where it is perfectly certain 

and obvious—e.g., Haploniscus with one and Ilyarachna 

with two pleonal somites.


Figure 4. Characteristics of asellota. A-E: Stenetrioidea. A: pleon; B: male first pleopod; 

C: female first (second) pleopod; D: male second pleopod; E: third pleopod, either sex- 

F-J: Aselloidea. F: pleon Asellus; G: pleon Stenasellus; H: male first pleopod; I: male 

second pleopod; J: third pleopod, either sex. K-M: Paraselloidea. K: pleon Janira; L: 

female first (second) pleopod; M: first and second male pleopod; N: third pleopod, either 

sex. (Figures A-E after Hansen, 1916, from Richardson, 1905; F-J after Birstein, 1951; 

K-N after Menzies, 1952.)


A KEY TO THE FAMILIES OF THE 

TRIBE ASELLOTA, SUBTRIBE 

PARASELLOIDEA" 

(Modified after Menzies, in press) 

1. None of the peraeopods modified for swimming . 5 

1. Some of the peraeopods modified for swimming . 2 

2. All peraeopods except first pair modified for 

swimming, similar in structure . . . Desmosomidae* 

2. Only peraeopods 5-6 or 7 inclusive paddle-like. 

Others simple walking legs or fossorial appendages 

3 

3. Only peraeopods 5-6 paddle-like, seventh a 

simple walking leg Ilyarachnidae* 

3. Peraeopods 5-7 inclusive paddle-like 4 

4. Peraeopods 5-7 inclusive lack dactyls . Munnopsidae 

4. Peraeopods 5-7 inclusive with dactyls . . Eurycopidae* 

5. Uropoda lack peduncle 6 

5. Uropoda with peduncle 7 

6. Molar process of mandible normal, strong, 

truncated at denticulate grinding apex . . Munnidae* 

6. Molar process of mandibles weak, 

pointed Pleurogonidae* 

7. Fourth and fifth peraeonal somites sometimes 

elongated twice as long as wide . . . . Ischnomesidae* 

7. All peraeonal somites similar in width, none twice 

as long as wide, most wider than long 8 

8. Palp of maxilliped with narrow similar articles 

all less than one-half the width of endite . . . . 9 

8. Palp of maxillipeds with last two articles narrow, 

others twice as wide 12 

9. Molar process of mandible normal, strong, truncated 

at denticulate grinding apex 10 

9. Molar process spiniform Jaeropsidae 

Type genus: Haploniscus Richardson. 

Diagnosis: Paraselloidea with free head. Eyes 

lacking. Mandibles normal with palp and expanded 

molar, lacinia, and setal row. Antennae shorter than 

body. All peraeopods simple walking legs; dactyl 

with at last one terminal claw, never three. Uropoda 

ventral, with peduncle and one ramus only. All 

peraeonal somites of similar width, wider than long. 

First three articles of maxillipedal palp narrow, less 

than one-half the width of endite. Pleon with one 

somite only. Anus widely separated from branchial 

chamber. (Modified after Menzies, 1956a, p. 9.) 

Composition: This family contains Haploniscus 

Richardson, Hydroniscus Hansen, and a proposed new 

genus, Antennuloniscus. All are now known from the 

North and South Atlantic. The majority of the species 

are abyssal, although shallow water species are 

known. 

Genus: HAPLONISCUS Richardson 

Type species: Nannoniscus bicuspis G. O. Sars, 

1885, Richardson, 1908a, p. 75. 

Richardson (op. cit.) established this species in 

Family: HAPLONISCIDAE 

10. Dactyl of seventh peraeopod with one elongated 

terminal claw 11 

10. Dactyl of seventh peraeopod with two 

short claws Antiasidat 

11. Coxal plates developed Dendrotiondai 

11. Coxal plates lacking Haploniscidae* 

12. Articles of maxillipedal palp one-half 

the width of endite Acanthaspididae* 

12. Articles of maxillipedal palp about as wide as 

endite 13 

13. Dactyls of peraeopods 2-7 inclusive with two 

principal claws and a smaller 

accessory claw Ianiridae* 

13. Dactyls of peraeopods 2-7 inclusive with one or 

two terminal claws but never three 14 

14. Molar process of mandible reduced to short 

setiferous tubercle Nannoniscidae 

14. Molar process normal, expanded apically and 

truncated, grinding 15 

15. Coxal plates present 17 

15. Coxal plates absent 16 

16. First peraeopod with two stout 

dactyls Echinothambemidae* 

16. First peraeopod with one dactyl only Macrostylidae* 

17. Body not markedly elongated 18 

17. Body length exceeds four times its 

width Thambematidae* 

18. Pleon with one somite, 

uropoda uniramous Ianirellidae* 

18. Pleon with two somites, uropoda biramous ... 19 

19. Coxal plates spiniform Schistosomidae 

19. Coxal plates 

rounded Abyssianiridae* and some Munnidae 

a Families with abyssal representatives marked with asterisk. 

1908 with Nannoniscus bicuspis G. O. Sars, 1885, as the 

type. At the same time Richardson described two 

additional species, H. excisus and H. retrospinis. Vanhoffen, 

1914, described two species, H. antarcticus and 

H. curvirostris. Hansen, 1916, added two more species, 

H. spinifer and H. armadilloides. Barnard, 1920, described 

H. dimeroceras, and Menzies, 1956a, added 

H. unicornis, and with Tinker (1960), H. robinsoni. 

Menzies (op. cit.) constructed a key to the species 

based upon the presence or absence of a complete 

seventh peraeonal somite. The collections now 

available show that this characteristic is not the best 

one to use, as the segmentation may be obscure, even 

though present, in certain species and is not described 

accurately for the known species. A more obvious 

characteristic divides the species of this genus into 

two groups which are tentatively considered as separate 

genera. 

Generic diagnosis: Haploniscidae with uniramous 

uropoda. Peraeon with 6-7 articulated somites. 

Epimera (coxal plates) not visible in dorsal view. 

Third article of the peduncle of the second antenna 

about as long as wide. (After Menzies, 1956a.)

Composition: To this genus belong all the species 

mentioned above except dimeroceras Barnard, which is 

transferred to Antennuloniscus. The 20 following new 

species described herein also belong to Haploniscus. 

Depth distribution: 

bicuspis (G. O. Sars) 

spinifer Hansen 

armadilloides Hansen 

antarcticus Vanhoffen 

curvirostris Vanhoffen 

excisus Richardson 

retrospinis Richardson 

unicornis Menzies 

robinsoni Menzies and 

Tinker 

Meters 

360-2465 Hansen, 1916, p. 30 

2970-3474 Hansen, 1916, p. 31 

1301-1301 Hansen, 1916, p. 32 

385-3397 Vanhoffen, 1914, p. 557 

3423-3423 Vanhoffen, 1914, p. 558 

3235-3235 Richardson, 1908a, p. 76 

713-713 Richardson, 1908a, p. 77 

5104-5122 Menzies, 1956a, p. 1 

2860-2858 Menzies and Tinker, 

1960, pp. 2-4. 

The genus is obviously eurybathyal, extending 

from bathyal depths to the abyss. To date it is un 

known from hadal depths (viz., below 6000 meters). 

Diagnostic characteristics: The diagnostic charac 

teristics are shown in Figure 5. The cephalon frontal 

margin (frons) may be quadrate, excavate, or convex 

G 

^3 

/tr-—-


18. Medial projection a simple knob 19 

18. Medial projection longer than 

wide unicornis Menzies 

19. Postero-lateral angles of pleon exceed twice 

the length of uropoda . . . . retrospinis Richardson 

19. Postero-lateral angles of pleon equal the 

length of uropoda percavix, n. sp. 

20. Lateral border of fourth peraeonal somite 

produced forward quadrifrons, n. sp. 

20. Lateral border of fourth peraeonal somite not 

produced forward 21 

21. Uropoda extending almost to the margin of the 

postero-lateral angles of the pleon . . . acutus, n. sp. 

21. Uropoda very short, less than one-half the 

length of the pleon postero-lateral 

angles spinifer Hansen 

22. Lateral borders of fourth peraeonal somite 

produced forward and pointed at antero-lateral 

angle elevatus, n. sp. 

22. Lateral borders of fourth peraeonal somite not 

produced forward or with blunt lateral angles 23 

23. Pleon set in from peraeon 27 

23. Lateral border of pleon and peraeon 

continuous minutus, n. sp. 

24. Frontal projection trifid 25 

24. Frontal projection entire 26 

25. Lateral border peraeon and pleon 

continuous tridens, n. sp. 

25. Lateral border pleon set in from 

peraeon capensis, n. sp. 

26. Uropods extending to postero-lateral 

margin of pleon nondescriptus, n. sp. 

26. Uropods not extending to postero-lateral 

margin of pleon princeps, n. sp. 

27. Uropods extending beyond postero-lateral 

margin of pleon excisus Richardson 

27. Uropods not extending to postero-lateral 

margin of pleon tropicalis, n. sp. 

Haploniscus bicuspis (G. O. Sars) 

Figure 6 A-D 

Synonyms: Nannoniscus bicuspis G. O. Sars, 1877, 

p. 352. Haploniscus bicuspis (G. O. Sars); — 

Richardson, 1908a, p. 75; — Hansen, 1916, pp. 

29-30, PI. II (incomplete). 

Diagnosis: Frontal border of cephalon with a 

median projection, base broad tapering to a point. 

Flagellum of first antenna with six articles. Lateral 

margins of peraeon and pleon continuous. Anterolateral 

margin of fourth peraeonal somite not produced 

forward, lateral angles blunt. First article of 

first antenna not concealed by cephalon dorsally. 

Uropods extending to posterior margin of pleon and 

to the end of the postero-lateral angles. 

Measurements: Length 2.90 mm. (G. O. Sars, 

1885, p. 122). 

Type locality: North Atlantic, west of Norway, 

latitude 63° 5' N., 988 meters (Hansen, 1916, p. 30) 

or possibly latitude 69° 46' N., 1220 meters. 

Distribution: Hansen (op. cit.) records the species 

from 15 Ingolf stations, and one—Station 113, latitude 

69°31'N., longitude 7° 06'W., 2465 meters—is 

from abyssal depth. Presumably it is eurybathial, 

extending from 360 meters to 2465 meters. 

Here it is recorded from the South Atlantic, 

L.G.O. Biotrawl No. 12, one male and two females, 

cat. no. 1-5; and L.G.O. Biotrawl No. 53, one male 

and four females, cat. no. 1-4. 

It is highly probable that Hansen (op. cit.) confused 

at least two species in what he called bicuspis: 

his illustrations, PI. II, show specimens in which the 

uropoda do and do not reach the posterior margin of 

the pleon. For this reason not all of his distributional 

data is cited here. I have not seen his specimens. 

The male that he figures is doubtless a distinct 

bathyal species and probably is identical with Richardson's 

retrospinis. It differs from the true bicuspis in 

having the apex of the male pleopod swollen and the 

uropods not reaching the posterior margin of the 

pleon; that is, the postero-lateral angles of the pleon 

are much produced. 

Affinities: This species is related to tricornis and 

tricornoides, from both of which it differs in lacking a 

projected base on the medial spine of the frontal 

margin of the cephalon. 

Haploniscus unicornis Menzies 

Figure 6 E-G 

Synonym: Haploniscus unicornis Menzies, 1956a, p. 9. 

Diagnosis: Frontal border of cephalon convex, 

with elongated (longer than breadth of base) spinelike 

horn. Lateral borders of pleon and peraeon 

continuous. Flagellum of first antenna with five 

articles. Postero-lateral angles of pleon produced 

beyond medial margin. First article of first antenna 

not concealed by cephalon dorsally. Antero-lateral 

border of fourth peraeonal somite not produced 

forward; lateral margin quadrate. Uropoda extending 

beyond apex of pleon but not to tips of posterolateral 

angles of pleon. 

Measurements: Female length 1.45 mm., width at 

second peraeonal somite 0.60 mm. (Menzies, 1956a, 

p. 9). 

Type locality: North Atlantic, L.G.O. Biotrawl 

No. 1, 5104-5122 meters, cat. no. 11759, A.M.N.H. 


Affinities: The elongate spine which is much larger 

than its base on the front of the cephalon distinguishes 

this species from the others. 

Haploniscus excisus Richardson 

Figure 6 H 

Synonyms: Haploniscus excisus Richardson, 1908a, 

pp. 75-77, Figs. 4-5. 

Diagnosis: Frontal border of cephalon excavated, 

entire. Flagellum of first antenna with five articles. 

Pleon set in from peraeon. Lateral borders of fourth


Figure 6. A-D: Haploniscus bicuspis (G. O. Sars). A: male dorsal view, 5.1 mm. long, 2.1 mm. 

wide, L.G.O. Sta. 12; B: anterior border fifth peraeonal somite; C: male first pleopod; 

D: first antenna. E-G: Haploniscus unicornis Menzies. E: first antenna; F: dorsal view type; 

G: ventral view pleotelson (after Menzies, 1956a). H: Haploniscus excisus Richardson, dorsal 

view type (after Richardson, 1908a). I-K: Haploniscus spinifer Hansen. I: dorsal view male; 

J: male first pleopod; K: first antenna (after Hansen, 1916, PL II). 

peraeonal somite not produced forward, lateral edges 

blunt. First article of first antenna not concealed by 

cephalon dorsally. Uropods extending beyond postero-lateral 

margin of pleon. 

Measurements: None available. 

Type locality: North Atlantic, east of Georges 

Bank, Albatross Station 2572, 3235 meters. 

Distribution: Known only from type locality.


Affinities: This species is closely related to H. 

tropicalis, from which it differs in having the uropoda 

extending beyond the postero-lateral margin of the 

pleon. 

Haploniscus spinifer Hansen 

Figure 6 I-K 

Synonyms: Haploniscus spinifer Hansen, 1916, p. 31, 

PI. II. 

Diagnosis: Frontal border of cephalon very slightly 

convex, entire. Flagellum of first antenna with five 

articles. Pleon set in from peraeon. Antero-lateral 

margin of fourth peraeonal somite not produced 

forward, lateral borders straight. First article of first 

antenna not concealed by cephalon dorsally. Posterolateral 

angles of pleon produced beyond medial 

border, uropods extending beyond medial border 

but not beyond postero-lateral angles. Apex of male 

first pleopod separated, swollen with two apical setae. 

Measurements: Largest male 2.8 mm. length (Hansen, 

1916, p. 31). 

Type locality: This is uncertain because Hansen 

lists three Ingolf stations and further cites some 

variability which seems too wide for a single species. 

The male pleopod which he figures came from a 

specimen from Ingolf Station 22, and this seems the 

Figure 7. A-C: Haploniscus minutus, n. sp. A: female dorsal view; B: first antennal flagellum; 

C: uropod. D-H: Haploniscus spatulifrons, n. sp. D: first antenna; E: second pleopod; F: male 

dorsal view; G: first pleopod; H: anus and uropod. I-K: Haploniscus tuberculatus, n. sp. 

I: female dorsal view; J: first antenna; K: anus and uropods.

logical choice of type locality; latitude, 58° 10' N., 

longitude 48° 25' W., 3474 meters, temperature 

1.4° C, four specimens. 

Distribution: Uncertain. It was collected from 

North Atlantic, Ingolf Station 22; South Atlantic, 

L.G.O. Biotrawl No. 18, one female, one male, cat. 

no. 1-22, and L.G.O. Biotrawl No. 16, three females, 

cat. no. 1-23. 

Affinities: This species appears to be most closely 

related to acutus, n. sp. 

Haploniscus minutus, new species 

Figure 7 A-C 


Diagnosis: Frontal border excised, entire. Pleon 

and peraeonal lateral borders continuous. Flagellum 

of first antenna with six articles. Postero-lateral 

angles of pleon not projected beyond medial margin. 

Dorsum of pleon smooth. First article of first antenna 

not concealed by cephalon. Uropoda extending 

beyond posterior medial margin of pleon. Anterolateral 

borders of fourth pleonal somite not projected 

forward. Dorsum of head not tuberculate. 

Measurements: Holotype female length 2.5 mm., 



No. 12, one female, cat. no. 1-15. 


Affinities: The species is close to H. excisus, 

differing markedly from it in having the lateral 

borders of the pleon and peraeon continuous. 

Haploniscus spatulifrons, new species 

Figure 7 D-H 


Diagnosis: Frontal border deeply excavate and 

with a pronounced pointed spatulate projection. Pleon 

and peraeon lateral borders continuous. Flagellum 

of first antenna with five articles. Postero-lateral 

angles of pleon not produced beyond medial margin. 


not concealed by cephalon. Uropods not extending 

to posterior border of pleon. Rami of sympod of male 

first pleopod round at apex. Antero-lateral borders of 

fourth peraeonal somite not produced forward. 


width pleon 2.0 mm. Allotype female length 2.6 mm., 


Type locality: South Atlantic, types and only 

specimens from L.G.O. Biotrawl No. 51, cat. no. 1-10. 


Affinities: The species is perhaps most nearly 

allied to H. bicuspis (G. O. Sars), but its spatulate 

rostrum distinguishes it. 


Haploniscus tuberculatum, new species 

Figure 7 I-K 


Diagnosis: Frontal border of cephalon convex, 

entire. Lateral borders of pleon and peraeon continuous. 

Flagellum of first antenna with four articles. 

Postero-lateral angles of pleon not projecting beyond 

medial margin. Dorsum of pleon tuberculate. First 

article of first antenna concealed by cephalon. 

Uropods extending beyond posterior margin of pleon. 

Antero-lateral borders of fourth peraeonal somite not 

produced forward. 



Type locality: South Atlantic, type and only specimen 

collected from L.G.O. Biotrawl No. 51, cat. no. 

1-20. 


Affinities: This species is most nearly related to 

H. parallelus, n. sp., from which it differs in having the 

lateral borders of the pleon and peraeon continuous. 

Haploniscus tridens, new species 

Figure 8 


Diagnosis: Frontal border deeply excavate and 

with a sharp trifid median projection. Pleon and 

peraeon lateral borders continuous. Flagellum of 

first antenna with five articles. Postero-lateral margins 

of pleon produced beyond medial margin. 


not concealed by cephalon. Uropods extending to 

posterior border of pleon. Rami of sympod of male 

first pleopod separated slightly at apex. Anterolateral 

borders of fourth peraeonal somite not produced 

forward. 

Measurements: Male holotype length 3.2 mm., 

width pleotelson 1.6 mm., allotype 4.2 mm. length, 


Type locality: South Atlantic, types and one fragment 

from L.G.O. Biotrawl No. 12, cat. no. 1-1. 

Distribution: Known from type locality and from 

South Atlantic, L.G.O. Biotrawl No. 212, one intersex, 

cat. no. 1-59, one intersex, cat. no. 1-61. 

Affinities: The species is most closely allied to 

H capensis, n. sp., differing from it most obviously in 

having the lateral borders of the pleon and peraeon 

continuous. 

Haploniscus elevatus, new species 

Figure 9 A-D 


Diagnosis: Frontal border excavate with a very 

slight, wide medial lobe. Pleon strongly set in from

100 


Figure 8. Haploniscus tridens, n. sp. A: dorsal view male holotype; B: left mandible; C: sixth 

peraeopod; D: maxilliped; E: uropod; F: second peraeopod; G: proximal border fifth 

peraeonal somite; H: third pleopod; I: first antenna; J: second pleopod; K: first pleopod. 

lateral border of peraeon. Flagellum of first antenna 

with five articles. Postero-lateral angles of pleon not 

produced beyond medial margin. Dorsum of pleon 

with large swelling medially near apex. First article 

of first antenna not concealed by cephalon. Uropods 

not extending to posterior border of pleon. Rami of 

sympod of male first pleopod united at apex. Anterolateral 

border of fourth peraeonal somite produced 

forward. 



Type locality: South Atlantic, type only from 

L.G.O. Biotrawl No. 52, cat. no. 1-11. 


Affinities: In general aspect H. elevatus resembles 

H. princeps, but the antero-lateral borders of peraeonal 

somites 3-4 are not as greatly produced forward. 

Haploniscus quadrifrons, new species 

Figure 9 E-G 


Diagnosis: Frontal border of cephalon entire and 

straight. Pleon set in from peraeon at lateral margins. 

Flagellum of first antenna with five articles. Posterolateral 

angles of pleon produced much beyond medial 

margin. Dorsum of pleon smooth. First article of 

first antenna not concealed by cephalon. Uropods

not extending to postero-lateral margin of pleon. 

Rami of sympod of male first pleopoda separated. 

Antero-lateral border of fourth peraeonal somite 

strongly produced forward. 



Figure 9. A-D: Haploniscus elevatus, n. sp. A: 

dorsal view male; B: first pleopod; C: first 

antenna; D: anus and uropod. E-G: Haploniscus 

quadrifrons, n. sp. E: dorsal view male 

type; F: first antenna; G: first pleopod. 

Type locality: South Atlantic, holotype and two 

fragments from L.G.O. Biotrawl No. 22, cat. no. 1-16. 

Distribution: Also found at L.G.O. Biotrawl No. 

23, one male, cat. no. 1-17. 

Affinities: This species is closely allied to H. 

princeps and H. elevatus, from which it is distinguished 

by the two dorsal tubercles on the pleon. 

Haploniscus princeps, new species 

Figure 10 A-C 


Diagnosis: Frontal border of cephalon excised, 

•vith a median slight but wide projection. Pleon 


set in from peraeon. Flagellum of first antenna with 

four articles. Postero-lateral angles of pleon projecting 

beyond medial margin. Dorsum of pleon 

smooth. First article of peduncle of first antenna not 

concealed by cephalon. Uropods not extending to 

postero-lateral border of pleon. Rami of sympod of 

male first pleopod joined at apex. Antero-lateral 

margins of fourth peraeonal somite produced forward. 


width pleotelson 0.65 mm. Male allotype length 2.2 

mm., (fragment). 

Type locality: South Atlantic, types plus three 

female paratypes, L.G.O. Biotrawl No. 53, cat. no. 

1-14. 


14, eleven females and one male, cat. no. 1-203. 

Affinities: H. princeps is closely allied to H. elevatus, 

H. nondescriptus, and H. quadrifrons. The absence of 

dorsal tubercles on the pleon and the short uropoda 

distinguish it. 

Haploniscus percavix, new species 

Figure 10 D-E 


Diagnosis: Frontal border of cephalon straight 

but with minute medial knob. Lateral margins of 

pleon and peraeon continuous. Flagellum of first 

antenna with five articles. Postero-lateral angles of 

pleon projecting beyond medial margin. Dorsum of 

pleon smooth. First article of first antenna not concealed 

by cephalon. Uropods extending to posterior 

margin of pleon. Antero-lateral angles of fourth 

peraeonal somite not produced forward. 

Measurements: Male holotype intersex length 2.4 

mm., width pleotelson 0.7 mm., female allotype 

length 3.4 mm., width pleotelson 1.5 mm. 

Type locality: South Atlantic, types plus one male 

intersex paratype, L.G.O. Biotrawl No. 53, cat. no. 

1-6. 


16, one male, one female, cat. no. 1-7, and North 

Atlantic, Atlantis Station 15, one female, cat. no. 1-207. 

Affinities: This species is related to H. retrospinis 

Richardson, from which it differs in having the 

postero-lateral angles of the pleon two times the length 

of the uropoda. 

Haploniscus tricornis, new species 

Figure 10 F-I 


Diagnosis: Frontal border cephalon excavate 

but with a medial apically trifid projection. Lateral 

margins of pleon and peraeon continuous. Flagellum 


angles of pleon not projecting beyond medial pleonal


Figure 10. A-C: Haploniscusprinceps, n. sp. A: female allotype dorsal view; B: first antenna; 

C: first pleopod male. D—E: Haploniscus percavix, n. sp. D: intersex holotype dorsal view; 

E: first antenna. F-I: Haploniscus tricornis, n. sp. F: dorsal view male type; G: first pleopod; 

H: first antenna; I: uropod and anus. J: Haploniscus nondescriptus, n. sp., female type dorsal 

view. 

margin. Dorsum of pleon with a ridge on each side of 

pleon. First article of first antenna not concealed 

by cephalon. Uropods not extending to posterior 

margin of pleon. Rami of sympod of male first 

pleopod joined at apex. Antero-lateral angles of 




Type locality: South Atlantic, holotype only, 



47, one male, one female, cat. no. 1-19. 

Affinities: The species H. tricornis and H. tricornoides 

seem closely related; in the latter the pleon is 

set in from the peraeonal lateral margin, but not in the 

former. 

Haploniscus nondescriptus, new species 


Figure 10 J

Diagnosis: Frontal border of cephalon excised 

with a broad low median projection. Pleon and peraeon 

lateral margins continuous. Flagellum of first 

antenna with five articles. Postero-lateral angles of 

pleon slightly exceeding median margin. Dorsum 

of pleon with a pair of slight short ridges above 

uropodal insertion. First article of peduncle of first 

antenna concealed from dorsal view by cephalon. 

Uropods not extending to postero-lateral margin of 

pleon. Antero-lateral margins of fourth peraeonal 

somite not produced forward. 



Type locality: South Atlantic, holotype female, 

plus two female paratypes, L.G.O. Biotrawl No. 

53, cat. no. 1-21. 


Affinities: This species is allied to H. princeps, but 

the uropoda extend to the posterior margin of the 

pleon at the postero-lateral angles. 

Haploniscus acutus, new species 

Figure 11 A-C 


Diagnosis: Frontal border of cephalon excavate, 

entire. Pleon inset from peraeonal lateral margin. 

Flagellum of first antenna with five articles. 

Postero-lateral angles of pleon projecting beyond 

medial pleonal margin. Dorsum of pleon smooth. 

First article of first antenna not concealed by cephalon. 

Uropods not extending to postero-lateral margin of 

pleon. Antero-lateral angles of fourth peraeonal 

somite not produced forward. 



Type locality: South Atlantic, holotype female, 



Affinities: Closely related to H. spinifer Hansen, 

but with the uropoda much longer—that is, extending 

almost to the tip of the postero-lateral angles of the 

pleon. 

Haploniscus parallelus, new species 

Figure 11 D-H 


Diagnosis: Frontal margin of cephalon convex, 

entire. Pleon set in from lateral margins of peraeon. 

Flagellum of first antenna with four articles. 

Postero-lateral angles of pleon not projecting beyond 

medial pleonal margin. Dorsum of pleon smooth. 

First article of first antenna concealed by cephalon. 

Rami of sympod of first male pleopod joined at apex. 

Uropods extending beyond posterior margin of 

pleon. Antero-lateral angles of fourth pleonal somite 

oroduced forward. 



width pleon 0.55 mm., allotype length 2.1 mm., width 

pleon 0.6 mm. 

Type locality: South Atlantic, types plus one female 

and two fragmentary paratypes, L.G.O. Biotrawl No. 

12, cat. no. 1-2. 

Distribution: Also taken from L.G.O. Biotrawl 

No. 52, two females, cat. no. 1-3. 

Affinities: This species is related to H. tuberculatus, 

but has the pleonal margin set in from the peraeonal 

margin. 

Haploniscus capensis, new species 

Figure 11 I-K 


Diagnosis: Frontal border of cephalon excavated 

and with very short trifid projection medially. Pleon 

set in from peraeon. Flagellum of first antenna 

with five articles. Postero-lateral angles of pleon 

projecting beyond medial pleonal margin and are 

medially recurved. Dorsum of pleon with short 

carinae above uropods. First article of first antenna 

not concealed by cephalon. Rami of male first 

pleopods not separated at apex. Uropods not extending 

to posterior margin of pleon. Antero-lateral 

angles of fourth pleonal somite not produced forward. 


width pleotelson 0.5 mm., allotype gravid length 

2.7 mm., width pleotelson 1.1 mm., and nine male, 

ten female, one juvenile paratypes. 

Type locality: South Atlantic, types only, L.G.O. 

Biotrawl No. 55, cat. no. 1-25. 


Affinities: This species resembles H. tridens in many 

respects, differing from it in having the lateral borders 

of the peraeon and pleon discontinuous. 

Haploniscus trituberculatus, new species 

Figure 11 L-Q, 


Diagnosis: Frontal border of cephalon excavate, 

entire. Pleon set in from peraeon. Flagellum of first 

antenna with four articles. Postero-lateral angles of 

pleon not projecting beyond medial pleonal margin. 

Dorsum of pleon with two tubercles located on anterior 

third of pleon and a large dorsally indented 

swelling medially near posterior margin. First article 

of first antenna concealed by cephalon. Rami of 

male first pleopods not separated at apex. Uropods 

concealed, extending to posterior margin of pleon. 


width pleotelson 0.55 mm., allotype length 2.6 mm., 

width pleotelson 0.7 mm., plus two male, three female, 

and two fragmentary paratypes. 

Type locality: South Atlantic, types, L.G.O. 

Biotrawl No. 51, cat. no. 1-24.


Figure 11. A-C: Haploniscus acutus, n. sp. A: holotype dorsal view; B: anus and uropod; 

C: first antenna. D-H: Haploniscus parallelus, n. sp. D: holotype dorsal view; E: first antenna; 

F: first peraeopod; G: anus and uropods; H: first pleopod. I-K: Haploniscus capensis, n. sp. 

I: holotype dorsal view; J: first pleopod; K; first antenna. L-Q_: Haploniscus trituberculatus, 

n. sp. L: holotype dorsal view; M: first antenna allotype; N: first antenna holotype; O: 

anus and uropod; P: first peraeopod; Q_: first pleopod.


14, one female fragment, cat. no. 1-202. 

Affinities: This species closely resembles H. telus, 

but has the pleon more quadrate than tapering or 

pointed. 

Haploniscus polaris, new species 

Figure 12 A-B 


Diagnosis: Frontal border convex, with minute 

medial projection. Pleon set in from peraeon. 

Flagellum of first antenna with four articles. Posterolateral 

angles of pleon projecting beyond medial 

margin. Dorsum of pleon with a slight ridge forward 

of each uropod. Uropods not extending to posterolateral 

border of pleon. Antero-lateral border of 





Type locality: South Atlantic, type only, L.G.O. 



Affinities: This species is closely related to H. 

antarcticus VanhdfFen, from which it differs in having 

a relatively longer pleon and in having only four 

articles, not five, to the flagellum of the first antenna. 

Haploniscus telus, new species 

Figure 12 C-E 


Diagnosis: Frontal border excised, entire. Pleon 

Figure 12. A-B: Haploniscus polaris, n. sp. A: fenaale holotype dorsal view; B: first antennal 

flagellum. C-E: Haploniscus telus, n. sp. C: female holotype dorsal view; D: anus and uropods; 

E: first antenna. F-G: Haploniscus tricornoid.es, n. sp. F: female holotype dorsal view; G: first 

antenna. H-I: Haploniscus tropicalis, n. sp. H: immature female holotype dorsal view; I: first 

antenna.


and peraeonal lateral borders continuous. Flagellum 


angles of pleon not projecting beyond medial margin. 


concealed by cephalon. Uropods not extending 

beyond posterior margin of pleon. Antero-lateral 

borders of fourth peraeonal somite not projected 

forward. Dorsum of cephalon tuberculate. 

Measurements: Holotype female, length 2.5 mm., 


Type locality: South Atlantic, type only L.G.O. 



Affinities: This species may be distinguished from 

H. trituberculatus, its nearest relative, because of its 

tapering pleon. 

Haploniscus tricornoides, new species 

Figure 12 F-G 


Diagnosis: Frontal border excised, with pronounced 

medial projections. Pleon set in from peraeon. 

Flagellum of first antenna with five articles. Posterolateral 

angles of pleon equal median projection in 

extent. Dorsum of pleon with slight carina above 

each uropod. First article of first antenna not concealed 

by cephalon. Uropods not extending to posterior 

margin of pleon. Antero-lateral borders of 

fourth peraeonal somite not projected forward. 

Measurements: Holotype female, length 2.5 mm., 


Type locality: South Atlantic, type only, L.G.O. 


Distribution: Known from type locality. 

Affinities: This species appears closely related to 

H. tricornis, from which it differs in having a longer 

cephalic projection and in having the pleon set in 

from the peraeon. 

Haploniscus tropicalis, new species 

Figure 12 H-I 


Diagnosis: Frontal border of cephalon excavated, 

entire. Flagellum of first antenna with four articles. 

Pleon set in from peraeon. Lateral border of fourth 

peraeonal somite not produced forward, lateral edges 

blunt. First article of first antenna not concealed by 

cephalon dorsally. Uropod not extending to posterolateral 

margin of pleon. 

Measurements: Holotype immature female length 

1.5 mm., width pleon 0.5 mm. 

Type locality: North Atlantic, Caribbean, holotype 

only, L.G.O. Biotrawl No. 100, cat. no. 1-65. 

Distribution: Also taken from L.G.O. Biotrawl No. 

101, one female with oostegites, cat. no. 1-66. 

Affinities: Closely related to H. excisus Richardson 

from which it differs in having shorter uropods and a 

narrower pleon. 

Haploniscus rugosus, new species 

Figure 13 A-C 


Diagnosis: Frontal border of cephalon almost 

transverse, with a bifid medial projection. Flagellum 

of first antenna with six articles. Pleon set in from 

peraeon. Lateral border of fourth peraeonal somite 

not produced forward, lateral edges blunt. First 

article of first antenna not concealed by cephalon 

dorsally. Uropod extending to posterior lateral 

margin of pleon. Dorso-lateral areas of peraeon 

tuberculate. Carina and tubercles located above 

uropodal insertion. 

Measurements: Length female holotype 3.1 mm., 

width pleotelson 1.1 mm., plus five juvenile paratypes. 

Type locality: South Atlantic, types from L.G.O. 


Distribution: One male and one female also collected 

from L.G.O. Biotrawl No. 14, cat. no. 1-9. 

Affinities: This species is unique in having a bifid 

frons and a tuberculate peraeon. 

Haploniscus ovalis, new species 

Figure 13 D-G 


Diagnosis: Frontal margin of cephalon straight, 

entire. Flagellum of first antenna with four articles. 

Pleon set in from peraeon. Antero-lateral areas of 

peraeonal somite 4 not produced forward, lateral 

borders convex. First article of first antenna concealed 

dorsally by cephalon. Uropods not extending to 

posterior margin of pleon. 



width pleotelson 0.6 mm., plus six female, one 

fragmentary male paratype. 

Type locality: South Atlantic, types, L.G.O. 



Affinities: Closely related to H. armadilloides 

Hansen, from which it differs in lacking the median 

projection on the cephalon. 

Haploniscid Fragments 

Fragmentary specimens of species of indeterminable 

Haploniscus were obtained from the following L.G.O. 

stations: 12, five fragments; 18, one fragment; 22, 

one fragment; 49, one fragment; 51, five fragments; 

52, one female crushed; 208, one fragment; 218, one 

female crushed; 229, one related closely to H.


Figure 13. A-C: Haploniscus rugosus,n. sp. A: female holotype dorsal view; B: first antenna; 

C: male first pleopod. D-G: Haploniscus ovalis, n. sp. D: male holotype dorsal view; 

E: third peraeopod; F: first pleopod; G: first antenna. 

parallelus; 231, one female crushed possibly related to 1. Postero-lateral angles of pleon projecting beyond 

H. minutus; 232, one female fragment related to 

T /-. r-\ -n- ^ i -NT onn 

species in L.G.O. Biotrawl No. 229. 

medial margin . . . . . 2 

2. Frontal border excised but with slight medial 

. & r ,. /r> ,, 

convexity dimeroceras (Barnard) 

2. Frontal border convex, with pronounced medial 

ANTENNULONISCUS, new genus projection 3 

Type species: Haploniscus dimeroceras Barnard, 1920, 3 " La ' eral borders of P er aeonal somites 5 ' 7 

A^r nno TII vxrii T- A T inclusive continuous armatus, n. sp. 

pp. 406-408, PI. XVII, Figs. 4-7. 

Generic diagnosis: Haploniscidae with the third 

article of the peduncle of the second antenna much 

3 Lateral border of peraeonal somites 5_6 

inclusive produced outward rostralus, n. sp. 

longer than wide. First five peraeonal somites always Antennuloniscus dimeroceras (Barnard) 

distinct. Figure 14 A_B 

Composition: In addition to the new species described 

herein and the type, none other is yet known Synonyms: Haploniscus dimeroceras Barnard, 1920, pp. 

in this genus. 406-408, PI. XVII, Fig. 4-7. 

Depth distribution: The species of this genus vary in Diagnosis: Frontal border excised, with even 

depth from 1280 meters (bathyal) to 5843 meters slight median convexity. Pleon set in from lateral 

(abyssal). border of peraeon. Flagellum of first antenna with six 

A KEY TO THE SPECIES OF articles. Postero-lateral angles of pleon projecting 

ANTENNULONISCUS beyond medial margin. Dorsum of pleon with a pair 

1. Postero-lateral angles of pleon not projecting 

of tubercles halfway from distal margin. Sympod of 

beyond medial margin ornalus, n. sp. male first pleopods separate at apex. First article of


Figure 14. A-B: Antennuloniscus dimeroceras (Barnard), male length 2.2 mm., width pleon 

0.6 mm. A: dorsal view male; B: first pleopod. C-F: Antennuloniscus armatus, n. sp. 

C: dorsal view; D: apex of pleon; E: first antenna; F: anus and uropod. G-J: Antennuloniscus 

rostratus, n. sp. G: dorsal view type female; H: anus and uropod; I: first antenna; 

J: cephalic horn. K-M: Antennuloniscus ornatus, n. sp. K: dorsal view male type; L: first 

antenna flagellum; M: first pleopod. 

first antenna not concealed by cephalon. Uropods 

not extending to postero-lateral margin of pleon. 

Antero-lateral borders of fourth peraeonal somite not 

produced forward. 

Measurements: Length 2.5 mm., width 1.0 mm., 

(Barnard, op. cit., 408). 

Type locality: 34° 25' S., 17° 55' E., 700 fathoms. 

Bottom green mud. Several males and females, 

S.S. PieterFaure, 20 August 1903 (S.A.M. No. A 4069). 

Distribution: South Atlantic, L.G.O. Biotrawl No. 

14, three females, cat. no. 1-40; L.G.O. Biotrawl No. 

22, three males, eight females, cat. no. 1-39; L.G.O. 

Biotrawl No. 23, one female, cat. no. 1-38; L.G.O. 

Biotrawl No. 54, eight males, nineteen females, cat. 

no. 1-37; L.G.O. Biotrawl No. 212, one female, cat. 

no. 1-60, North Atlantic, L.G.O. Biotrawl No. 231, 

one female, cat. no. 1-52. 

Affinities: The excised frontal border of the cephalon 

sets this species apart from the others. 

Antennuloniscus armatus, new species 

Figure 14 C-F 


Diagnosis: Frontal borders convex, with sharp, 

elongate, median spine. Lateral margins of pleon

and peraeon continuous. Flagellum of first antenna 

with four articles. Postero-lateral angles of pleon 

extending beyond medial margin. Dorsum of pleon 

smooth. First article of first antenna not concealed by 

cephalon. Uropods not extending to posterior border 

of pleon. 

Measurements: Length 2.6 mm, width pleon 0.8 

mm. 


51, one female, cat. no. 1-34. 

Distribution: Known also from L.G.O. Biotrawl 

No. 52, one male, two female, cat. no. 1-35. 

Affinities: This species appears most closely related 

to A. rostratus, from which it differs mainly in having 

the lateral margins of the peraeon and pleon continuous. 

Antennuloniscus rostratus, new species 

Figure 14 G-J 


Diagnosis: Frontal border convex with a sharp 

upcurved spine medially. Lateral margin of pleon 

peraeon continuous. Flagellum of first antenna with 

five articles. Postero-lateral angles of pleon extending 

beyond medial margin. Dorsum of pleon smooth. 

First article of first antenna not concealed by cephalon. 

Uropods not extending to postero-lateral border 

of pleon. 




52, three females, cat. no. 1-36. 


Affinities: The long and broad rostrum of this 

species is distinctive; also the lateral border of the 

sixth peraeonal somite is produced outward from that 

of the seventh. 

Antennuloniscus ornatus, new species 

Figure 14 K-M 


Diagnosis: Frontal margin of cephalon convex. 

Pleonal and peraeonal lateral margins continuous. 

Flagellum of first antenna with six articles. Posterolateral 

angles of pleon not projecting beyond medial 

pleonal margin. Dorsum of pleon with ridge near 

each lateral margin. First article of first antenna not 

concealed by cephalon. Rami of male first pleopod 

separated at apex. Uropods extending to posterior 

margin of pleon. Antero-lateral borders of fourth 

peraeonal somite not produced forward. 




No. 47, two males, cat. no. 1-33. 


Distribution: Also known from L.G.O. Biotrawl 

No. 201, one male, cat. no. 1-223. 

Affinities: The dorsal elevation of the cephalon 

and the carinae on the pleon separate this species 

from all the others. Its nearest known relative is 

possibly A. dimeroceras (Barnard), a species also known 

from the South Atlantic. 

Genus: HYDRONISCUS Hansen 

Type species: Hydroniscus abyssiHansen, 1916 

Diagnosis: Haploniscidae with the pleon and last 

three peraeonal somites fused into a solid piece. 

Uropoda extremely reduced or entirely absent. 

Third article of peduncle of first antenna longer than 

wide but lacking the angulate projection characterizing 

Haploniscus. 

Composition: The genus contains three species, two 

from the North Atlantic and one from the South 

Atlantic. They are markedly different from one 

another. According to Wolff (1960), Birstein has 

found a species of Hydroniscus in the North Pacific. 

A KEY TO THE SPECIES OF 

HYDRONISCUS 

1. Uropoda present ornatus, n. sp. 

1. Uropoda absent 2 

2. Rostrum pointed abyssi Hansen 

2. Rostrum blunt guadrifrons, n. sp. 

Hydroniscus ornatus, new species 

Figure 15 A-H 


Diagnosis: Hydroniscus with distinct pointed postero-lateral 

angles projecting laterally from pleon. 

Single-jointed uropoda present, not extending beyond 

posterior margin of pleon. Flagellum of first antenna 

with four articles, that of second with 12 articles. 


width pleon 1.7 mm., allotype female length 4.0 mm., 


Type locality: South Atlantic, types plus three female 

paratypes from L.G.O. Biotrawl No. 51, cat. no. 

1-43. 


No. 217, one female, cat. no. 1-211, in the South 

Atlantic. 

Affinities: Ornatus is possibly closely related to 

guadrifrons, from which it differs in having a rounded 

rostrum and in having very pronounced posterolateral 

angles on the pleon. 

Hydroniscus quadrifrons, new species 

Figure 15 I-M 


Diagnosis: Hydroniscus with minute postero-lateral 

angles on pleon. Quadrate single-jointed uropods


Figure 15. A-H: Hydroniscus ornatus, n. sp. A: dorsal view female allotype; B: maxilliped; 

C: dorsal view uropod; D: first peraeopod; E. mandible; F: second antenna; G: first 

antenna; H: first pleopod. I-M: Hydroniscus quadrifrons, n. sp. I: dorsal view male holotype; 

J: first antenna; K: second pleopod; L: first pleopod; M: uropod. N-O: Hydroniscus 

abyssi Hansen (after Hansen, 1916). N: dorsal view female; O: pleon and anus. 

present. Flagellum of first antenna with five articles. 

Dorsum of cephalon tuberculate, rostrum blunt at apex. 

Measurements: Male holotype length 2.7 mm., width 

pleon 1.0 mm., allotype length 3.2 mm., width pleon 

1.1 mm., and four male and six female paratypes. 


No. 231, types, cat. no. 1-51. 

Distribution: Also known from L.G.O. Biotrawl 

No. 214, one female, cat. no. 1-53; L.G.O. Biotrawl 

No. 229, one male and one fragment, cat. no. 1-58; 

L.G.O. Biotrawl No. 232, one fragment, cat. no. 

1-55; L.G.O. Biotrawl No. 233, one male, one frag 

ment, cat. no. 1-56; L.G.O. Biotrawl No. 234, three 

males, cat. no. 1-57. 

Affinities: This species is related to H. abyssi 

Hansen, from which it differs in having a blunt 

rostrum and in having uropods, and to ornatus, from 

which it differs in having a blunt rostrum. 

Hydroniscus abyssi Hansen 

Figure 15 N-O 

Synonyms: Hydroniscus abyssi Hansen, 1916, p. 33, 

PI. II.

Diagnosis: Hydroniscus with a spearpoint-shaped 

pleon lacking lateral projections. Uropoda absent. 

Flagellum of first antenna with five articles, that of 

second antenna with nine articles. 

Measurements: Female holotype length 2.8 mm. 

Type genus: Ischnomesas Richardson, 1908a. 

Diagnosis: Paraselloidea with head and first 

peraeonal somite joined. Eyes lacking. Mandibles 

generally lacking palp, molar expanded, lacinia and 

setae row present. Antennae shorter than body. All 

peraeopods simple walking legs; dactyl with at least 

one terminal claw, never three. Uropoda terminal 

uniramous. Fifth peraeonal somite generally much 

longer than wide. Last two articles of maxillipedal 

palp narrow, others as wide as endite. Pleon with onetwo 

distinct separated somites. Anus widely separated 

from branchial chambers. 

Composition: This family contains Ischnomesus, 

Haplomesus, Heteromesus, and Stylomesus. The genus 

Ischnosoma was replaced by Ischnomesus, and the genus 

Rhabdomesus was subsequently found to be a synonym 

of Ischnomesus (see Wolff, 1956). Like Haploniscidae, 

the family is characteristically abyssal but contains 

shallow water representatives as well. The absence of 

a mandibular palp is not a constant characteristic of 

the family: a triarticulate palp is present in /. 

simplissimus, but only a rudimentary seta remains in 

/. paucispinis and nothing at all in the remaining species. 

A KEY TO THE GENERA OF 

THE ISCHNOMESIDAE 

(Modified after Wolff, 1956) 

1. Uropoda with a single article 2 

1. Uropoda with two articles 3 

2. Pleon and three posterior peraeonal somites 

fused into a single piece. Third article of first 

antenna markedly elongate Haplomesus 

2. Pleon and two posterior peraeonal somites 

fused into a single piece. Third article of first 

antenna minute Heteromesus 

3. First pleonal somite separate from 

pleotelson Ischnomesus 

3. First pleonal somite fused with 

pleotelson Stylomesus 

Genus: ISCHNOMESUS Richardson, 1908a 

Synonyms: Ischnosoma G. O. Sars, 1868. Rhabdomesus, 

Richardson, 1908a, p. 81. Ischnomesus Richardson 

1908a, p. 81. 

Type species: Ischnosoma bispinosum G. O. Sars, 1868. 

Diagnosis: Ischnomesidae with a distinctly twojointed 

pleonal somite. Uropoda with two articles. 

Remarks: The genus may be indistinctly split into 

two groups on the basis of the fundamental structure 

of the male first and second pleopods. Unfortunately, 


Family: ISCHNOMESIDAE 

Type locality: North Atlantic, Ingolf Station 38, 

latitude 59° 12' N., longitude 51° 05' W., 3521 meters. 

One female specimen. 

Distribution: An abyssal species known only from 

type locality. 

these characteristics are not known for all species and 

therefore have not been used in the key. To the most 

primitive group belong those species in which the 

stylus of the male second pleopod is shorter than the 

exopod and the lateral projections of each ramus at the 

apex of the first pleopod are quite evident. To this 

group belong the species /. bispinosum, I. paucispinis, 

I. multispinis, I. sparcki, I. decemspinosus, I. bidens, etc. 

A secondarily derived group has a long semi-coiled 

stylus which inserts into depressions on the interior 

surface of the sympod of the male first pleopod. The 

lateral expansions of the sympod are generally coalesced 

with the sympod, giving the apex a blunt 

appearance under low magnification. To this group 

belong the remaining species, /. caribbicus, I. bruuni, 

I. bacilloides, I. wolffi, etc. 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

bispinosum (G. O. Sars) 

bacillopsis Barnard 

armatus Hansen 

bacilloides (Beddard) 

profundus Hansen 

sparcki Wolff 

bruuni Wolff 

bacillus (Beddard) 

andriashevi Birstein 

94-1100 

1280-1280 

2702-2702 

2652-2652 

3521-3521 

6660-7000 

6960-7000 

3292-3292 

4000-6560 

Nine new species may be added to the list of known 

species. All are considered in the following key. 


ISCHNOMESUS 

1. Dorsum of pleon with stout spines 2 

1. Dorsum of pleon smooth, lacking spines . . . . 4 

2. Postero-medial margin of pleon with 

spines magnificus, n. sp. 

2. Postero-medial margin of pleon entire, lacking 

spines 3 

3. Lateral borders of pleon each with only 

three spines multispinis, n. sp. 

3. Lateral borders of pleon each with more than ten 

spines sparcki Wolff 

4. Sixth peraeonal somite with a long lateral spine 

on either side 5 

4. Sixth peraeonal somite without a lateral spine on 

either side 8 

5. Lateral spine of fifth peraeonal somite directed 

posteriorly at about 20° angle to peraeonal 

axis 16 

5. Lateral spine of fifth peraeonal somite directed 

more laterally, about perpendicular from peraeonal 

axis 6


6. Posterior margin of seventh peraeonal somite 

with a medial projection . . . . bacilloides (Beddard) 

6. Posterior margin of seventh peraeonal somite 

entire medially 7 

7. Lateral spine of sixth peraeonal somite directed 

at a 45° angle from peraeonal 

axis uiolffi, n. sp. 

7. Lateral spine of sixth peraeonal somite 

directed at a 75° angle from peraeonal 

axis bruuni Wolff 

8. Pleon with postero-lateral angles projecting 

beyond medial margin bidens, n. sp. 

8. Pleon lacking projecting postero-lateral angles . . 9 

9. Fifth peraeonal somite with long lateral spine . . 10 

9. Fifth peraeonal somite without lateral spines . . 12 

10. Dorsum of fourth peraeonal somite with 

spines at anterior part decemspinosus, n. sp. 

10. Dorsum of fourth peraeonal somite smooth, without 

spines 11 

11. Pleonal lateral borders strongly 

convex elegans, n. sp. 

11. Pleonal lateral borders 

subparallel bacillus (Beddard) 

12. Lateral border of pleon each with a stout 

seta and three small setae . . . . paucispinis, n.sp. 

12. Lateral borders of pleon lack stout setae . . . . 13 

13. First peraeonal somite with a stout antero-lateral 

spine 14 

13. First peraeonal somite without a stout anterolateral 

spine simplissimus, n. sp. 

14. Postero-lateral margin of pleon without angles, 

entire and smooth 17 

14. Postero-lateral margin of pleon with distinct 

postero-lateral angles 15 

15. Pleon with a pair of minute projections anterior 

to uropodal insertion 

(postero-lateral angles) caribbicus, n. sp. 

15. Pleon without a pair of projections anterior to 

postero-lateral angles profundus Hansen 

16. Pleon constricted in front of 

uropods armatus Hansen 

16. Pleon not constricted in front of 

uropods bacillopsis (Barnard) 

17. Hand of first peraeopod about as wide 

as long bispinosum (G. O. Sars) 

17. Hand of first peraeopod three times longer 

than wide andriashevi Birstein 

Ischnomesus profundus Hansen 

Figure 16 A-D 

Synonyms: Ischnomesus profundus Hansen, 1916, pp. 

56-57, PI. 4; —Wolff, 1956, pp. 88-89, Fig. 1. 

Diagnosis: Ischnomesus with lateral spines on first 

peraeonal somite only, other somites lacking lateral 

spines. Pleon with sharp postero-lateral angles at 

uropods; posterior margin convex and lacking spines 

or setae. Male first pleopods with pronounced lateral 

extensions at apex (uropods lost). (From Hansen, op. 

cit., illustration and description.) 

Measurements: Male length 4.0 mm. (Hansen, op. 

cit.) 

Type locality: North Atlantic, south of Davis 

Strait, Ingolf Station 38, latitude 59° 12' N., longitude 

51°05'W., 3521 meters, temperature 1.3° C. type 

only (Hansen, op. cit.). 


Affinities: This species appears to be related to the 

Caribbean species /. caribbicus, n. sp., from which it 

differs in lacking pleonal projections anterior to the 

uropodal insertion. 

Figure 16. A-D: Ischnomesus profundus Hansen 

(after Hansen, 1916). A: dorsal view posterior 

; B: dorsal view head; C: dorsal view 

male; D: ventral view pleon. E-I: Ischnomesus 

bispinosum, (G. O. Sars) (after G. O. Sars, 

1896). E: dorsal view female; F: dorsal 

view head and anterior thoracic segments, 

male; G: mandible; H: first pleopod; 

I: uropod. J: Ischnomesus armatus Hansen 

(after Hansen, 1916), dorsal view male. 

Ischnomesus bispinosum (G. O. Sars) 

Figure 16 E-I 

Synonyms: Ischnosoma bispinosum G. O. Sars, 1865, 

p. 34; — 1897, pp. 123-124, PI. 52; Hult, 1941, pp. 

62-66, Figs. 16-18, and references (incomplete). 

Diagnosis: Ischnomesus with a spine on lateral 

border of first peraeonal somite only; dorsal spine 

lacking. Pleon pyriform, without postero-lateral 

angles. Lateral projections on apex of male first

pleopods scarcely evident, endite of male second pleopod 

short, not coiled. Uropoda biramous (derived 

from Sars' illustrations, 1897; this may be an error in 

illustration). 

Measurements: Adult female length 3 mm., male 

length 2.5 mm. (G. O. Sars, 1897, p. 124). 

Type locality: Christiania Fjord, Norway. 

Distribution: Lofoten, Norway, Ireland, to Gulf of 

Naples in the Mediterranean (Hult, 1941, p. 65), 

depth range 90 to 1100 meters. 

Affinities: The smooth spineless pleon of this 

species sets it apart from the others as a fundamentally 

more primitive species. 

Ischnomesus armatus Hansen 

Figure 16 J 

Synonyms: Ischnomesus armatus Hansen, 1916, pp. 

59-60, PI. 4;—Wolff, 1956, pp. 89-90, Fig. 2. 

Diagnosis: Ischnomesus with lateral spines on peraeonal 

somites 1-6 inclusive. Lateral spines of first four 

somites directed acutely forward, those of somites 5 

and 6 directed acutely hindward. Pleon constricted 

above uropods, lateral and posterior margins smooth 

and lacking setae or spines. Lateral projection at 

apex o[ male first pleopods joined with sympod. 

(From Hansen, op. cit.) 

Measurements: Length male 4.8 mm. (Hansen, 

op. cit.) 

Type locality: North Atlantic, Davis Strait, Ingolf 

Station 36, latitude 61° 50' N., longitude 56° 21' W., 

2702 meters, temperature 1.5° G, two males (Hansen, 

op. cit.). 

Distribution ; Known also from the North Atlantic 

from L.G.O. Biotrawl No. 234, one male, cat. no. 

1-68. 

Affinities: This species appears related to the 

South Atlantic /. bacillopsis (Barnard), from which it 

differs in having the pleon constricted in front of the 

uropods. 

Ischnomesus caribbicus, new species 

Figure 17 A-B 


Diagnosis: Ischnomesus with lateral spines on first 

peraeonal somite only. Dorsal spines lacking. Pleon 

with distinct sharp but small angles above uropodal 

insertion. Medial posterior margin of pleon truncated, 

smooth, lacking spines or setae. Lateral projection 

at apex of male first pleopod largely joined to 

sympod, distal margin with nine setae. 

Measurements: Length holotype male 7.8 mm., 


Type locality: North Atlantic, Caribbean, L.G.O. 

Biotrawl No. 100, type only, cat. No. 1-72. 



Affinities: This species appears to be most nearly 

related to /. profundus Hansen, from which it differs in 

having a minute angle projecting anterior in front 

of each uropodal insertion. 

Ischnomesus simplissimus, new species 

Figure 17 C-F 


Diagnosis: Ischnomesus lacking lateral or dorsal 

spines on peraeonal or pleonal somites. Mandible 

with triarticulate palp, last article minute and with 

a single apical seta. Pleon margins smooth, lacking 

angles, setae, or spines, apex pointed. 

Measurements: Female holotype length 9.1 mm., 



52, one holotype female and one paratype female, cat. 

no 1-98. 

Distribution: Taken also at L.G.O. Biotrawl No. 

53, eight fragmentary females, cat. no. 1-99. 

Affinities: The presence of a triarticulate mandibular 

palp sets this species apart; otherwise it is 

distinct in lacking a stout antero-lateral spine from the 

first peraeonal somite. 

Ischnomesus multispinis, new species 

Figure 17 G-H 


Diagnosis: Ischnomesus with dorsal spines on all 

body somites. First, third, fourth, and fifth somites 

with lateral spines. Pleon with three spines on either 

side, dorsum with a pair of spines. Sympodal apex 

with lateral projections directed caudad; rami 

separated at apex. Posterior margin of pleon without 

spines or setae. 

Measurements: Injured male holotype length 7.4 

mm., width pleon 0.7 mm. 


Biotrawl No. 107, holotype only, cat. no. 1-77. 


Affinities: By virtue of the three spines on each 

lateral margin of the pleon this species is most 

closely related perhaps to I. spdrcki Wolff, from which 

it differs in having fewer lateral pleonal spines. The 

apex of the male pleopods also indicates the affinity 

between the two. 

Ischnomesus wolffi, new species 

Figure 18 A-C 


Diagnosis: Ischnomesus with lateral spines on 

peraeonal somites 1-6 inclusive. Those of somites 5 

and 6 projecting posteriorally. Pleon with posterolateral 

angles at uropod insertion, otherwise smooth,

114 


Figure 17. A-B: Ischnomesus caribbicus, n. sp. A: dorsal view male holotype; B: first pleopod. 

C-F: Ischnomesus simplissimus, n. sp. C: mandible holotype; D: dorsal view female holotype; 

E: first antenna; F: para type uropod. G-H: Ischnomesus multispinis, n. sp. G: dorsal view 

male holotype; H: first pleopod. 

entire; posterior margin broadly convex, smooth. 

Lateral projection of first male pleopod largely 

coalesced with sympod, apex of each with six 

setae. 

Measurements: Holotype fragment male length 



No. 52, type only, cat. no. 1-96. 


No. 18, six fragmentary males, cat. no. 1-45. 

Affinities: This species appears most closely 

related to the Pacific species /. bruuni Wolff, from 

which it differs in having the lateral spines of the 

sixth peraeonal somite less laterally projecting—that 

is, at a 45° angle instead of a 75° angle from the 

peraeonal axis. 

Ischnomesus magnificus, new species 

Figure 18 D 


Diagnosis: Ischnomesus with lateral and dorsal 

spines on fifth peraeonal somite (other anterior 

somites missing). Sixth and seventh peraeonal somites 

lacking lateral spines but having small dorsal 

spines. Pleon with seven spines on each side, 16


Figure 18. A-C: Ischnomesus wolffi, n. sp. A: dorsal view male holotype fragment; B: apex 

male pleopod; C: second male pleopod. D: Ischnomesus magnificus. n. sp., dorsal view female 

holotype fragment. E-H: Ischnomesus bidens, n. sp. E: dorsal view male holotype fragment; 

F: second male pleopod; G: male first pleopod; H: uropod. 

dorsal spines, and four terminal spines. Pleopods 

missing. 

Measurements: Female holotype fragment, length 

pleonal somites: first, 0.5 mm.; second, 4.5 mm.; 

peraeonal somites: sixth, 1.2 mm.; seventh, 1.05 mm.; 





Affinities: This highly spinous species most nearly 

resembles /. sparcki Wolff, but differs from it in having 

spines on the distal border of the pleon. The species 

is obviously among the largest of the known asellotes. 

Ischnomesus bidens, new species 

Figure 18 E-H 


Diagnosis: Ischnomesus with angular postero-lateral 

projections on pleon, extending to postero-medial 

margin of pleon. Sympod of male first pleopod with 

acute lateral projection at apex. Endite of male second 

pleopod short, not projecting beyond apex of exopod. 

Sixth and seventh peraeonal somites without dorsal or 

lateral spines. Dorsum of pleon smooth, without spines. 

Measurements: Holotype male fragment, length 

1.8 mm., width of pleotelson 1.0 mm.


Figure 19. A-G: Ischnomesuspaucispinis, n. sp. A: uropod; B: first antenna; C: first male 

pleopod; D: maxilliped; E: mandible; F: dorsal view male holotype minus cephalon; 

G: dorsal view male paratype fragment. H-K: Ischnomesus decemspinosus, n. sp. H: dorsal 

view male holotype; I: second male pleopod; J: first male pleopod; K: first antenna. 

L-N: Ischnomesus elegans, n. sp. L: dorsal view male holotype; M: first male pleopod; 

N: second male pleopod. 


No. 12, type plus one male paratype fragment, cat. 

no. 1-95. 


Affinities: This species is unique in having the 

postero-lateral angles of the pleon projecting beyond 

the medial distal border. Otherwise it belongs with 

the group of species lacking a lateral spine from the 

sixth peraeonal somite. 

Ischnomesus paucispinis, new species 

Figure 19 A-G 

Synonyms: None.

Diagnosis: Ischnomesus with lateral spines only on 

first peraeonal somite. Dorsal spines lacking. Pleon 

with stout setae on either side of pronounced posterolateral 

angle, three smaller setae follow, apex with 

two minute setae. Lateral projections at apex of male 

first pleopod well developed, apex each with six 

stout setae. 

Measurements: Holotype male fragment length 

4.3 mm. (minus cephalon), width pleon 0.65 mm. 


No. 12, holotype and one male fragment, cat. no. 

1-93. 


Affinities: The stout setae on the lateral margin of 

he pleon distinguish this species from the others, as 

foes the fact that the fifth peraeonal somite lacks 

ateral spines. 

Ischnomesus decemspinosus, new species 

Figure 19 H-K 


Diagnosis: Ischnomesus with lateral spines on perae- 

:ial somites 4-5 inclusive; somites 2—4 each with a 

: air of dorsal spines. Pleon ovoid, smooth, devoid of 

:pines, setae, or sharp postero-lateral angles. Lateral 

D rejections at apex of first male pleopod well developed, 

apex of each with seven stout setae. 




Xo. 14, type and one fragment, cat. no. 1-44. 


Affinities: The fact that the dorsal surface of the 

fourth peraeonal somite has spines sets this species 

apart from the majority, plus the fact that the fifth 

peraeonal somite has long lateral spines. 

Ischnomesus elegans, new species 

Figure 19 L-N 


Diagnosis: Ischnomesus with lateral spines on 

peraeonal somites 2-5 inclusive. Dorsal spines lacking. 

Pleon with sharp postero-lateral angles at uropods, 

margins entire and smooth, posterior margin truncated 

and smooth. Lateral projection at apex of male 

first pleopod largely joined to sympod, distal margin 

without setae. 

Measurements: Holotype male length 10.01 mm. 

(minus cephalon), width pleon 1.5 mm. 


214, type only, cat. no. 1-76. 


Affinities: This species is closely related to /. 

bacillus (Beddard), but has the pleonal border swollen 

and not subparallel. 


Ischnomesus species indeterminate 

Unidentifiable fragments of Ischnomesus were 

collected at L.G.O. Biotrawl no. 12, eleven fragments; 

18, five fragments; 52, two fragments; 53, three 

fragments; 98, one fragment; 217, one fragment; 

220, one fragment; 233, one fragment. 

Genus: HAPLOMESUS Richardson 

Synonyms: Haplomesus Richardson, 1908a, p. 81; 

— Hansen, 1916, p. 59; — Wolff, 1956, p. 87. 

Type species: Ischnosoma quadrispinosa G. O. Sars, 

1879, p. 435. 

Diagnosis: Ischnomesidae with third article of 

first antennae elongate, two and a half times or more 

longer than the fourth. Pleon with a single somite 

only. Uropoda with a single article. Fifth to seventh 

peraeonal somites fused with pleon. 

Remarks: Eight species, all from the Atlantic and 

Pacific, are presently known from this genus: 

Depth Range (Meters) 

Species Least Greatest 

1. quadrispinosus (G. O. Sars) 510 4150 

2. angustus Hansen 698 2137 

3. insignis Hansen 698 2707 

4. tenuispinis Hansen 698 3474 

5. modestus Hansen — 2258 

6. brevispinis Birstein 5510 5690 

7. cornutus Birstein 6471 6571 

8. orientalis Birstein 4000 4150 

Additionally, three new species are described in this 

paper from abyssal depths of the North and South 

Atlantic. 

A KEY TO THE SPECIES OF HAPLOMESUS 

1. Third peraeonal somite with lateral spines ... 2 

1. Third peraeonal somite without lateral spines . . 5 

2. Fourth peraeonal somite with lateral 

spines modestus Hansen 

2. Fourth peraeonal somite without lateral spines . . 3 

3. Apex of pleon medially incised . . . . bifurcatus, n. sp. 

3. Apex of pleon truncated or curved not medially 

incised 4 

4. Dorsum of pleon medially with paired 

carinae ornatus, n. sp. 

4. Dorsum of pleon medially with a single 

swelling quadrispinosus (G. O. Sars) 

5. Fourth peraeonal somite with lateral spines ... 6 

5. Fourth peraeonal somite without lateral spines . . 8 

6. Dorsum of pleon with at least one pair of 

stout spines near midline tenuispinis Hansen 

6. Dorsum of pleon without paired stout spines ... 7 

7. Lateral spines of first and fourth peraeonal somites 

massive, longer than wide insignis Hansen 

7. Lateral spines of first and fourth peraeonal 

somites short, no longer than wide . . tropicalis, n. sp. 

8. Posterior border of pleon trilobed . . . angustus Hansen 

8. Posterior border of pleon with one median 

lobe only gorbunovi Gurjanova" 

a More probably this species belongs in the genus 

Stylomesus.


Figure 20. A-D: Haplomesus angustus Hansen. A: dorsal view immature male; B: ventral 

view male pleon; C: dorsal view male pleon; D: dorsal view head of male. E: Haplomesus 

modestus Hansen, dorsal view mutilated female. F-H: Haplomesus quadrispinosus (G. O. Sars). 

F: ventral view male pleon from Ingolf Sta.. 36; G: dorsal view male cephalon from Ingolf 

Sta. 36; H: ventral view median lamella of male abdominal operculum from Ingolf Sta. 36. 

I-J: Haplomesus tenuispinis Hansen. I: dorsal view fragment of mutilated female from Ingolf 

Sta. 22; J: dorsal view of cephalon of female from Ingolf Sta. 24. K-M: Haplomesus tropicalis, 

n. sp. K: apex of male pleopod; L: dorsal view of male pleon and uropods; M: dorsal 

view male holotype. N-P: Haplomesus insignis Hansen. N: ventral view male pleon; O: 

dorsal view male cephalon; P: dorsal view male.

Haplomesus anguslus Hansen 

Figure 20 A-D 

Synonyms: Haplomesus anguslus. Hansen, 1916, 

pp. 61-62. PI, V. 

Diagnosis: Haplomesus with lateral spines on the 

first peraeonal somite only. Uropoda longer than 

wide. Pleon with pronounced postero-lateral angles 

dorsum without carinae. 

Measurements: Juvenile male 4.8 mm. long. 

Full-grown males 9-12 mm. Length presumed 

(Hansen, op. cit.). 

Type locality: North Atlantic, south of Denmark 


30° 29' W.; 1135 fathoms (2137 meters), temperature 

3.0° C. (Hansen, op. cit.). 

Distribution: Also found by Ingolf Station 125, 

latitude 68° 08' N., longitude 16° 02'W., 729 fathoms 

(1373 meters), temperature —0.8° C. This species was 

not represented in Vema collections, which appear to 

lie too far south of the distributional area of the 

species. Gorbunov (1946, p. 123) reports this species 

in the Arctic from 698 meters. 

Affinities: This species superficially resembles 

S. gorbunovi Gurjanova from the Arctic; however, the 

postero-medial margin of the pleon is trilobed rather 

than a single lobe as in the latter. 

Haplomesus modestus Hansen 

Figure 20 E 

Synonyms: Haplomesus modestus. Hansen, 1916, 

pp. 65-66, PL V. 

Diagnosis: Haplomesus with lateral spines on 

somites 2, 3, and 4 and probably also on 1. Pleon 

without projecting postero-lateral angles, dorsum 

smooth and lacking spines or carinae. Uropoda not 

much longer than wide and not extending beyond 

posterior margin. 

Measurements: 1.8 mm., fragment (Hansen, op. 

cit.). 

Type locality: North Atlantic, Davis Strait, 

Ingolf Station 24, latitude 63° 06' N., longitude 

56° 00' W., 1199 fathoms (2258 meters), temperature 

2.4° C., one mutilated female specimen (Hansen, op. 

cit.). 


Affinities: The presence of lateral spines on 

peraeonal somites 2-4 inclusive distinguishes this 

species from the others that are known. 

Haplomesus quadrispinosus (G. O. Sars) 

Figure 20 F-H 

Synonyms: Ischnosoma quadrispinosum G. O. Sars, 

1879, p. 435; — 1885, p. 126, PL II. Haplomesus 

quadrispinosus (G. O. Sars), Richardson, 1908a, p. 81; 

— Hansen, 1916, pp. 59-61, PL II. 


Diagnosis: Haplomesus with lateral spines on the 

first and third peraeonal somites only. Uropoda 

short, no longer than wide. Peraeon and pleon 

markedly tuberculate. Pleon without postero-lateral 

angles, dorsum with a single medial swelling. Apex of 

male first pleopods without lateral projections and 

with three terminal setae. 

Measurements: Three males, largest 5 mm. (after 

Hansen, op. cit.). 

Type locality: West of Norway, latitude 67° 56' N., 

longitude 4° 11' E., 1423 meters, temperature — 1.4°C 


Distribution: North Atlantic. The Ingolf collected 

it at nine stations: 

Davis Strait: Station 24, latitude 63° 06' N., 


2.4° C., two specimens; Station 36, latitude 61° 50' 

N., longitude 56° 21' W., 2702 meters, temperature 

1.5° C, two specimens. 

South of Davis Strait: Station 38, latitude 59° 12' 


1.3° C, one specimen. 

North of the Faeroes: Station 139, latitude 63° 36' 

N., longitude 7° 30'W., 1322 meters, temperature 

—0.6° C., two specimens. 

East of Iceland: Station 102, latitude 66° 23' N., 


—0.9° C., five specimens. 

Northeast of Iceland: Station 120, latitude 67° 

29' N., longitude 11° 32' W., 1666 meters, temperature 

— 1.0° C, one specimen; Station 119, latitude 

67° 53' N., longitude 10° 19' W., 1902 meters, 

temperature —1.0° C., one specimen. 

South of Jan Mayen: Station 113, latitude 69° 31' 


—1.0° C., five specimens; Station 116, latitude 


—0.4° C, one specimen. 

The species was not represented in the Lamont 

collections. Gorbunov (1946, p. 123) records it from 

510 and 698 meters in the Arctic, and Birstein (1960, 

p. 15) cites it from the North Pacific at 4000-4150 

meters. 

Affinities: This species resembles the new species 

ornatus considerably, but lacks paired carinae on the 

dorsum of the pleon. 

Haplomesus tenuispinis Hansen 

Figure 20 I-J 

Synonyms: Haplomesus tenuispinis Hansen, 1916, 

pp. 64-65, PL V. 


peraeonal somites 1 and 4 only. Pleon with pronounced 

postero-lateral angles, dorsum with paired 

stout spines. Uropoda longer than wide and extending 

beyond the posterior border of the pleon.


Measurements: 3.1 mm. long (estimated, Hansen, 

op. cit.). 


Station 24, latitude 63° 06' N., longitude 56° 00' 

1199 fathoms (2258 meters), temperature 2.4° C. 


Distribution: Also taken from North Atlantic, 

south of Davis Strait, Ingolf Station 22, latitude 

58° 10' N., longitude 48° 25' W.; 1845 fathoms (3474 

meters), temperature 1.4° C. (perhaps a distinct 

species) (Hansen, op. cit.). Also reported by Gorbunov 

(1946, p. 123) from 698 meters in the Arctic. 

Remarks: A specimen, female fragment, with an 

additional pair of stout spines on the dorsum of the 

seventh peraeonal somite was captured by Vema at 

L.G.O. Biotrawl No. 231, cat. no. 231. It mav 

represent a distinct species. The spines (actuallv 

stout setae) on the pleon distinguish this species from 

the others. 

Haplomesus tropicalis, new species 

Figure 20 K-M 


Diagnosis: Haplomesus with lateral spines on firs: 

and fourth peraeonal somites in male, and on firs: 

only in female. Pleon with sharp incurved posterolateral 

angles, dorsum without stout spines or carinae 

apex convex. Uropoda longer than wide styliform. 

extending beyond apical margin of pleon. Male 

Figure 21. A-B: Haplomesus ornatus, n. sp. A: dorsal view male holotype; B: first pleopod. 

C-I: Haplomesus bifurcatus, n. sp. C: maxilliped; D: first male pleopod; E: first male 

paraeopod; F: first antenna; G: maleuropod; Ff: dorsal view male holotype; I: second 

male pleopod.

pleopods each with simple rounded apex bearing 

three setae. 


width pleon 0.2 mm. Allotype length 4.1mm., width 

pleon 0.4 mm. 

Type locality: North Atlantic, Mediterranean, 

L.G.O. Biotrawl No. 76, holotype and allotype, cat. 

no. 1-105. 

Distribution: Also taken at L.G.O. Biotrawl No. 

95, one male fragment, cat. no. 1-106, Caribbean. 


to H. insignis Hansen, from which it differs in having 

much smaller lateral body spines. 

Haplomesus insignis Hansen 

Figure 20 N-P 

Synonym: Haplomesus insignis Hansen, 1916, p. 63, 

PL V. 

Diagnosis: Haplomesus with massive lateral spines 

on peraeonal somites 1 and 4 only. Pleon with pronounced 

postero-lateral angles, dorsum without 

stout setae or carinae. Uropoda longer than wide 

and extending beyond posterior margin of pleon. 

Measurements: Male 4.5 mm. long (Hansen, op. 

cit.). 



1435 fathoms (2702 meters), temperature 1.5° C. 


Distribution: Taken also by Vema at L.G.O. 

Biotrawl No. 234, one anterior fragment, cat. no. 

1-69. Reported by Gorbunov (1946, p. 123) from 

698 meters in the Arctic. 

Affinities: This species appears to be related to 

H. tropicalis, but has much more massive lateral body 

spines. 

Haplomesus ornatus, new species 

Figure 21 A-B 



peraeonal somites 1 and 3 only. Peraeon strongly 

tuberculate. Apex of pleon truncated, posterolateral 

angles lacking, dorsum with paired medial 

carinae. Apex of male pleopods each with blunt 

lateral process and six setae. 




18, one male and one male fragment, cat. no. 1-49. 

Distribution: Also from L.G.O. Biotrawl No. 52, 

one male, cat. no. 1-47, and L.G.O. Biotrawl No. 214, 

two fragments, cat. no. 1-78. 

Affinities: This species is near to the North Atlantic 

/. quadrispinosis (G. O. Sars), but has carinae on the 

dorsum of the pleon which the latter lacks. 


Haplomesus bifurcatus, new species 

Figure 21 C-I 



peraeonal somites 1 and 3 only. Peraeon strongly 

tuberculate. Pleon without pronounced posterolateral 

angles; apex incised, dorsum with mid-central 

swelling with deep pit. Uropoda minute, as wide as 

long and not extending to apex of pleon. Male first 

pleopods each with minute lateral projections and 

six setae. 




12, holotype and one male fragment paratype, cat. no. 

1-48. 


Affinities: This species resembles H. ornatus, but the 

indentation of the posterior border of the pleon distinguishes 

it. 

Genus: HETEROMESUS Richardson 

Synonyms: Heteromesus Richardson, 1908a, p. 81; 


Type species: Ischnosoma thomsoni Beddard. 

Diagnosis: Ischnomesidae with the third article of 

the first antenna minute. Pleon with a single somite 

only. Uropoda with a single article. Sixth and 

seventh peraeonal somites fused with pleon. 

Composition: Thirteen species of this genus are 

known. Additionally, one new one is described in this 

paper. They are bathyal to abyssal in depth distribution 

and are known from only the Arctic, the 

North Atlantic (including the Caribbean), and the 

North Pacific (four species). 

1. thomsoni (Beddard) 

2. spinosus (Beddard) 

3. greeni (Tattersall) 

4. spinescens Richardson 

5. granulatus Richardson 

6. dentatus Hansen 

7. longiremis Hansen 

8. schmidtii Hansen 

9. frigidus Hansen 

10. similis Richardson 

11. gigas (Birstein) 

12. scabriusculus (Birstein) 

13. robustus (Birstein) 

Least 

3750 

1829 

364 

2155 

713 

1505 

698 

956 

698 

— 

6560 

5450 

5450 

Greatest 

3750 

1829 

700 

3337 

3235 

1505 

2707 

956 

1435 

2995 

8430 

5450 

5817 


HETEROMESUS a 

It is not easy to provide a key to the species of Heteromesus 

because entire specimens are not yet known for all 

the species. The following key therefore is incomplete but 

probably useful.


1. Pleon with spines or spine-like projections at the 

lateral margins 2 

1. Pleon without spines or spine-like projections at 

lateral margins 5 

2. Posterior border of pleon with a pair of 

spine-like projections thomsoni (Beddard) 

2. Posterior border of pleon without spine-like projections 

3 

3. Posterior border of pleon medially 

excised bifurcatus, n. sp. 

3. Posterior border of pleon rounded 4 

4. First peraeonal somite laterally with 

two spines similis Richardson 

4. First peraeonal somite laterally with 

only one spine dentatus Hansen 

5. Uropoda over five times longer than their 

greatest width longiremis Hansen 

5. Uropoda considerably less than five times longer 

than wide 6 

6. Lateral borders of first peraeonal somite with 

one spine each 7 

6. Lateral borders of first peraeonal somite with 

2-3 spines 8 

7. Uropoda only two times as long as 

wide granulatus Richardson 

7. Uropoda four times as long as 

wide schmidtii Hansen 

8. Lateral border of first peraeonal somite with 

three spines each spinosus (Beddard) 

8. Lateral border of first peraeonal somite with two 

spines each 9 

9. Uropoda curving toward midline of 

pleon fngidus Hansen 

9. Uropoda straight 10 

10. Last peduncular article of second antenna 

without a spine in distal inner 

extremity greeni (Tattersall) 

10. Last peduncular article of second 

antenna with a prominent spine at distal 

inner extremity spinescens Richardson 

a Birstein's three species not included; these are deep Pacific 

species. 

Heteromesus longiremis Hansen 

Figure 22 A-B 

Synonyms: Heteromesus longiremis Hansen, 1916, pp. 

68-69, PI. VI. 

Diagnosis: Heteromesus having pleon smooth laterally, 

lacking spines. Uropoda over five times as long 

as wide. 

Measurements: Length mutilated female specimen 

3.5 mm. (Hansen, op. cit.). 



2707 meters, temperature 1.5° C, type only. 


Affinities: The very long uropods and the lack of 

lateral spines on the pleon distinguish this species from 

the others. 

Heteromesus bifurcatus, new species 

Figure 22 C 


Diagnosis: Heteromesus with a single spine (curved 

toward apex) on each side of the pleon. Apex of pleon 

medially incised. Uropoda about three times as 

long as wide. Last free peraeonal somite without 

spines at postero-lateral border. 

Measurements: One female fragment 3.5 mm. long, 



Biotrawl No. 94, type only, cat. no. 1-107. 

Figure 22. A-B: Heteromesus longiremis Hansen. 

A: dorsal view mutilated female; B: dorsal 

view mutilated male. C: Heteromesus bifurcatus, 

n. sp., dorsal view female fragment. D: 

Heteromesus granulatus Richardson, dorsal view 

female. E: Heteromesus spinescens Richardson, 

dorsal view male. 


Affinities: This species is very close to H. dentatus 

Hansen, from which it differs in having the apex of the 

pleon incised. 

Heteromesus granulatus Richardson 

Figure 22 D 

Synonyms: Heteromesus granulatus Richardson, 

1908a, pp. 82-83, Figs. 14-17. 

Diagnosis: Heteromesus with spines lacking from 

lateral border of pleon, apex of pleon rounded, entire, 

lacking spine-like projections. Uropoda only about 

twice as long as wide. 

Measurements: None available.

Type locality: North Atlantic, Albatross Station 

2547, south of Martha's Vineyard, 713 meters, 41 

females, four males, cat. no. 38969 U.S.N.M., 

Washington (Richardson, op. cit.). 

Distribution: Known also from Albatross Station 

2572, southeast of Georges Bank, 3235 meters, two 

males, one female; Albatross Station 2571, southeast of 

Georges Bank, 2479 meters, one male; Albatross 

Station 2208, south of Block Island, 2155 meters, 

one male, six females; Albatross Station 2078, off 

Georges Bank, 912 meters, one female (Richardson, 

op. cit.). 

Affinities: This species appears closely related to 

H. schmidtii Hansen, but has much shorter uropods. 

Heteromesus spinescens Richardson 

Figure 22 E 

Synonyms: Heteromesus spinescens Richardson, 1908a, 

pp. 83-84, Fig. 18. 

Diagnosis: Heteromesus with pleon lacking lateral 

spines, apex rounded, entire, lacking spine-like projections. 

Uropoda less than five times as long as wide, 

not bent toward midline. Lateral border of first 

peraeonal somite with two spines. Last peduncular 

article of first antenna with a prominent spine at distal 

extremity (Richardson, op. cit. illustration.). 


Type locality: North Atlantic, Albatross Station 

2105, off Virginia, 2557 meters, one male, cat. no. 

38970 U.S.N.M., Washington (Richardson, op. cit.). 

Distribution: Also taken from Albatross Station 

2714, south of Martha's Vineyard, 3337 meters, two 

females; Albatross Station 2208, south of Block Island, 

2155 meters, two females Albatross Station 2084, off 

Georges Bank, 2361 meters, one female; Albatross 

Station 2571, southeast of Georges Bank, 2479 meters, 

five females. 

Affinities: This species seems related to H. greeni 

(Tattersall) and differs from it in having the long spine 

in the inner angle of the last peduncular article of the 

second antenna. 

Heteromesus similis Richardson 

Figure: none available 

Synonyms: Heteromesus similis Richardson, 1911, pp. 

531-532. 

Diagnosis: Heteromesus with spines at lateral border 

of pleon, posterior border entire, rounded, without 

spine-like projections or excisions. First peraeonal 

somite laterally with two spines. 


Type locality: Talisman Station 31, northeast of 

San Miguel in the Azores, 22 August 1883, 2995 

meters, one fragment. 



Affinities: This species is perhaps related to 

H. dentatus Hansen, from which it differs in having two 

spines instead of one at the lateral margin of the first 

peraeonal somite. 

Genus: STYLOMESUS Wolff 

Synonyms: Stylomesus Wolff, 1956, pp. 87-88, 97. 

Type species: Rhabdomesus inermis Vanhoffen, Wolff, 

1956, pp. 87-88, 97. 

Diagnosis: Ischnomesidae having uropods with 

two articles. Seventh peraeonal somite fused with 

pleon. Third article of first antenna more than twice 

as long as fourth. 

Composition: Wolff (1956) put only inermis in this 

genus. The species S. inermis was collected by the 

German South Polar Expedition (1901-1903) in the 

Antarctic Indian Ocean northwest of the Gauss 

station from a depth of 2450 meters. Four additional 

new species are described in this paper. Birstein 

(1960) described four abyssal species from the North 

Pacific, and Gurjanova (1946) described one from the 

Arctic. 


STYLOMESUS a 

1. Pleon composed of three fused somites 2 

1. Pleon composed of two fused somites 4 

2. Apex of male first pleopod with lateral projections 

6 

2. Apex of male first pleopod without lateral projections 

3 

3. Inner margin of uropodal peduncle 

spinulate spinulosus, n. sp. 

3. Inner margin of uropodal peduncle 

smooth simplex, n. sp. 

4. Uropodal peduncle just extending to end of 

pleon inermis (Vanhoffen) 

4. Uropodal peduncle extending beyond end of pleon 

by about one-half its length 5 

5. Dorsum of pleon strongly granulate, without 

central depression granulosus, n. sp. 

5. Dorsum of pleon smooth with central transverse 

depression elegans, n. sp. 

6. Apex of pleon between uropods 

triangulate regularis, n. sp. 

6. Apex of pleon between uropods evenly rounded 7 

7. Lateral margin of male first pleopods with 

two distinct lobes at distal half . . . . productus, n. sp. 

7. Lateral margin of male first pleopods with one 

distinct lobe at distal half simulans, n. sp. 

a Following species not included: 

1. gorbunovi (Gurjanova) 

2. wolffi Birstein 

3. menziesi Birstein 

4. gracilis Birstein 

5. pacificus Birstein. 

Stylomesus inermis (Vanhoffen) 

Figure 23 

Synonyms: Rhabdomesus inermis Vanhoffen, 1914, 

pp. 560-561, Fig. 88. Stylomesus inermis (Vanhoffen), 

Wolff, 1956, pp. 87, 97-99.


Figure 23. Stylomesus inermis (Vanhoffen). A: dorsal view female 5.8 mm. long, width pleon 

0.8 mm.; B: first male pleopod; C: first paraeopod; D: second male pleopod; E: maxillipedal 

epipod; F: maxilliped; G: mandibular molar; H: second female pleopod; I: 

sixth paraeopod; J: female operculum; K: lateral view female; L: female anus and 

uropods; M: male uropod. 

Diagnosis: Stylomesus without lateral spines on 

peraeonal or pleonal somites. Body granulate. Pleon 

with lateral swellings indicating only one coalesced 

somite. First article of uropod extending to apex of 

pleon. Apex of male pleopods with slight lateral 

process and each with six apical setae. 

Measurements: 5.1 mm. total length; width somite 

one is 0.9 mm. (Wolff, op. cit.). 

Type locality: Antarctic Indian Ocean, near 

Gauss Station, latitude 65° 31' S., longitude 85° 17' E., 

2450 meters (Wolff, op. cit.). 

Distribution: This species was collected by Vema 

from the South Atlantic Ocean at: L.G.O. Biotrawl 

No 12, three female, two male, one fragment, cat. 

no. 1-71; L.G.O. Biotrawl No. 210, one female, one 

fragment, cat. no. 1-70; L.G.O. Biotrawl No. 214, 

three female, three fragments, cat. no. 1-75. 

Affinities: The pleon of this species has only two 

fused somites. Because the uropodal peduncles are 

short, the species is distinguished from granulosus and 

elegans, both of which have longer uropodal peduncles. 

Stylomesus granulosus, new species 

Figure 24 A-C 

Synonyms: None.


Figure 24. A-C: Stylomesus granulosus, n. sp. A: dorsal view male holotype; B: first male 

pleopod, C: first male paraeopod. D-G: Stylomesus spinulosus, n. sp. D: dorsal view fragment 

female holotype; E: second pleopod male paratype; F: uropod male; G: first 

pleopod male. H-K: Stylomesus elegans, n. sp. H: dorsal view male holotype; I: first pleopod 

male; J: first male paraeopod; K: male uropod. 


peraeon or pleon. Body strongly granulate. Pleon 

with lateral swellings indicating only one coalesced 

somite. First article of uropoda extending beyond 

apex of pleon by one-half its length. Apex of male 

first pleopods with short truncated lateral processes 

and each with four apical setae. 


width pleon 1.1 mm., female allotype length 7.2 mm., 



51, types plus one male and four fragmentary para- 

types, cat. no. 1-101 


Affinities: This species is allied with S. elegans, from 

which it differs in lacking a central transverse depression 

from the dorsum of the pleon 

Stylomesus spinulosus, new species 

Figure 24 D-G 

Synonyms: None.



peraeon or pleon. Body strongly granulate. Pleon 

with lateral swellings indicating two coalesced somites. 

First article of uropoda marginally spinulous and 

extending to apex of pleon. Apex of male first pleopods 

with short blunt lateral processes, each apex 

with 10-11 setae. 

Measurements: Female holotype fragment length 



No. 12, holotype and three fragmentary paratypes, 

cat. no. 1-102. 



to S. simplex, from which it differs in having the inner 

margin of the uropodal peduncle spinulate. 

Stylomesus elegans, new species 

Figure 24 H-K 


Diagnosis: Stylomesus with a short lateral spine on 

first peraeonal somite; other somites and pleon without 

lateral spines. Pleon with lateral swellings indicating 

only one coalesced somite. First article of uropod 

extending beyond apex of pleon by one-half its length. 

Second article shorter than first. Apex of male pleopods 

with blunt lateral processes; six setae at apex. 




51, type only, cat. no. I-100. 

Distribution: Also taken from the North Atlantic, 

L.G.O. Biotrawl No. 208, one pleon fragment, cat. no. 

1-220. 

Affinities: This species resembles granulosus most 

closely, but has a depressed area on the dorsum of the 

pleon. 

Stylomesus regularis, new species 

Figure 25 A-D 



peraeon, pleon with three fused somites. Margin of 

uropoda spinulate. Uropodal peduncle extending 

slightly beyond apex of pleon. Dorsum of pleon 

without central depressed area. Apex of male first 

pleopod with lateral expansions and with eight setae. 

Measurements: Holotype male length 5.75 mm, 

with pleon 0.6 mm., allotype length 6.0 mm., width 

pleon 0.55 mm., plus cephalon fragment. 


No. 218, types only, cat. no. 1-219. 

Distribution: Found only at type locality. 

Affinities: This species is related to S. simulans and 

S. productus, from which it differs in having a triangulate 

pleonal apex between the uropods. 

Stylomesus simplex, new species 

Figure 25 E-J 



pleon. Body with few granules. Pleon with lateral 

swellings indicating two coalesced somites. First 

Figure 25. A-D: Stylomesus regularis, n. sp. 

A: dorsal view male holotype; B: first male 

pleopod; C: male gnathopod; D: ventral 

view uropod female allotype. E-J: Stylomesus 

simplex, n. sp. E: fourth male paraeopod; 

F: lateral view male holotype; G: second 

male pleopod; H: dorsal view male holotype 

(minus cephalon); I: ventral view female 

pleon; J: first male pleopod. 

article of uropod extending to apex of pleon; margin 

smooth. Apex of male pleopods without lateral 

processes and each with a single apical seta. 

Measurements: Male holotype (minus cephalon) 

length 3.0 mm., width pleon 0.4 mm. 


No. 12, type and one female allotype fragment, cat. 

no. 1-73.

Distribution: Known also from the South Atlantic, 

from L.G.O. Biotrawl No. 53, one female, cat. no. 

1-204, and from L.G.O. Biotrawl No. 212, one female, 

cat. no. 1-74. 

Affinities: This species is close to S. spinulosus, from 

which it differs in lacking spines from the uropodal 

peduncle. 

Stylomesus productus, new species 

Figure 26 A-C 


Diagnosis: Stylomesus with three fused pleonal 

somites. Uropodal peduncle extending far beyond 

apex of pleon. Dorsum of pleon with two pits, one at 

apex, one in front of apex. Apex of male first pleopod 

with seven setae and lateral expansions. Lateral 

margin male first pleopods with two large swellings 

just behind apex. Seventh peraeonal somite not 

separated from pleon. 

Measurements: Length last six somites (inclusive of 

pleon) 3.0 mm., width pleon 0.6 mm. 


No. 214, type male fragment only, cat. no. 1-214. 


Affinities: This species is near to S. simulans, but 

differs in having an additional lobe along the lateral 

border of the male first pleopods at its distal half. 

Stylomesus simulans, new species 

Figure 26 D-F 


Diagnosis: Stylomesus with three fused pleonal 

somites. Uropodal peduncle just extending beyond 

apex of pleon. Dorsum of pleon with two pits, one at 

apex, one in front of apex. Apex of each male first 

pleopod with seven setae and lateral expansions. 

Lateral margins male first pleopod with only one 

swelling just behind apex. Seventh peraeonal somite 

fused with pleon. 

Measurements: Length male last five somites 1.9 





Affinities: This species resembles S. productus 

Type genus: Macrostylis G. O. Sars, 1863. 

Diagnosis: Paraselloidea with free first peraeonal 

somite. Mandible with pointed molar bearing setae 

at apex; palp lacking. First three articles of maxillipedal 

palp as wide as endite, last two narrow, small. 

Uropoda styliform; uniramous. First pair of antennae 

shorter than peduncle of second pair of antennae. 


Family: MACROSTYLIDAE 

Figure 26. A-C: Stylomesus productus, n. sp. 

A: dorsal view male (minus cephalon); B: 

first male pleopod; C: male pleopod. 

D-F: Stylomesus simulans, n. sp. D: dorsal 

view male fragment; E: first male pleopod; F: 

first male pleopod. 

rather closely, but has only one lobe instead of two 

along lateral margin of the male first pleopods at its 

distal half. 

Stylomesus species indeterminable 

Indeterminate species of Stylomesus were taken in 

L.G.O. Biotrawl No. 12, two fragments, and L.G.O. 

Biotrawl No. 47, two fragments. 

All peraeopods ambulatory. Pleon consisting of a 

single somite only. Anus separated from branchial 

chamber. 

Composition: This family contains only one genus, 

Macrostylis. It is quite possible that Pseudomesus Hansen 

should be referred to this family, and in that event 

the Pseudomesidae should be canceled. I have not


seen specimens of Pseudomesus and therefore hesitate to 

make that assignment. 

Genus: MACROSTYLIS G. O. Sars, 1863 

Type species: Macrostylis spinifera G. O. Sars, 1863, 

p. 15. 

Diagnosis: Macrostylidae with the fourth peraeopods 

shorter than the others. Uropoda elongate. 

First three peraeonal somites almost fused into a 

single unit. 

Composition: Although Wolff (1956) correctly 

indicates that ten species are known from the genus, 

he omitted M. spinifera from his key to the species. 

In depth the species range from the shallow water of 

Christiania Fjord to the floor of the Philippine trench 

at 10,000 meters. Here eight additional species are 

described from the abyssal Atlantic, where previously 

only one abyssal species was known. 

The uropods are terminal and two-jointed in 

Macrostylis, and above them there is often a deep 

notch in the dorsum of the pleon. The uropoda are 

not dorsal in insertion as shown by Wolff, 1956, 

p. 100, Fig. 13, but terminal. 

THE KNOWN SPECIES OF MACROSTYLIS 

Species 

1. spiniceps Barnard 

2. longipes Hansen 

3. subinermis Hansen 

4. longiremis (Meinert) 

5. elongata Hansen 

6. hadalis Wolff 

7. galatheae Wolff 

8. latifrons Beddard 

9. abyssicola Hansen 

0. spinifera G. O. Sars 

Depth Range {Meters) 

Least Greatest 

— 

— 

1090 

149 

— 

— 

9820 

— 

3229 

4 

1280 

1412 

1902 

218 

1591 

7270 

10,000 

3749 

3521 

1761 

A KEY TO THE SPECIES OF MACROSTYLIS 

1. Apical margin of pleon with conspicuous setae . 2 

1. Apical margin of pleon without conspicuous 

setae 8 

2. Postero-lateral margins of fourth peraeonal somite 

pointed and projecting 3 

2. Postero-lateral margins of fourth peraeonal somite 

evenly rounded 4 

3. Uropodal peduncle longer than 

pleon hirsuticaudis, n. sp. 

3. Uropodal peduncle not as long as pleon . . . . 5 

4. Postero-lateral angles of peraeonal somites 5-7 

with a stout seta 6 

4. Postero-lateral angles of peraeonal somites 

5-7 without stout spine longipes Hansen 

5. Peduncle of uropods longer than greatest 

width of pleon spinifera (G. O. Sars) 

5. Peduncle of uropods shorter than greatest width of 

pleon longiremis (Meinert) 

6. Fourth somite of peraeon narrower than third 

and fifth somites setifer, n. sp. 

6. Fourth peraeonal somite as wide as third and 

fifth 

7. Postero-lateral angles of cephalon 

7 

sharply pointed 

7. Postero-lateral angles of cephalon 

caribbkus, n. sp. 

evenly rounded 

8. Medial apex of pleon 

subinermis Hansen 

emarginate bifurcatus, n. sp. 

8. Medial apex of pleon convex or truncated, never 

bifurcated 9 

9. Apex of pleon truncated truncatex, n. sp. 

9. Apex of pleon pointed or rounded 10 

10. Cephalon wider than peraeon with posterolateral 

angles projecting spiniceps Barnard 

10. Cephalon not wider than peraeon, postero-lateral 

angles not projecting beyond peraeonal margin . 11 

11 Pleon with bulbous swellings at uropod 

insertion making the pleon appear 

constricted cephalad of uropods . . . . vemae, n. sp. 

11 Pleon not swollen laterally in front of uropod 

insertion 12 

12 First and second peraeonal somites subequal in 

length 13 

12 First peraeonal somite much shorter or longer than 

second 14 

13. Cephalon quadrate in shape, as wide in 

13 

14 

14. 

15. 

front as behind abyssicola Hansen 

Cephalon narrower in front than behind . . . . 15 

First peraeonal somite much shorter than 

second minutus, n. sp. 

First peraeonal somite much longer than 

second . hadalis Wolff 

Cephalon narrower than peraeon 17 

15. Cephalon as wide as peraeon 16 

16. Postero-lateral angles of cephalon rounded, 

lacking setae galatheae Wolff 

16. Postero-lateral angles of cephalon pointed 

with stout seta at apex bipunctatus, n. sp. 

17. Pleon with statocysts elongata Hansen 

17. Pleon without statocysts latifrons Beddard 

Macrostylis truncatex, new species 

Figure 27 A-G 


Diagnosis: Cephalon narrower in front than rear, 

front rounded. Fourth peraeonal somite as wide as 

third and fifth, lateral borders rounded. First 

peraeonal somite slightly longer than second. Uropodal 

peduncle not longer than pleon width; dorsum 

of pleon with a pair of carinae in front of uropods, pits 

and sensory organs lacking, apical border truncated 

lacking plumose setae. Apex of male first pleopods 

simple, rounded, without stout spines or lateral projections 

but with nine setae. First antenna with fivearticles 

(male). 






Affinities: The truncated nature of the pleonal 

apex distinguishes this species.


Figure 27. A-C: Macrostylis truncatex, n. sp. A: dorsal view holotype; B: first antenna; 

C: first male pleopod. D-E: Macrostylis abyssicola Hansen. D: dorsal view female (3.9 mm.); 

E: first and second antenna. F-H: Macrostylis setifer, n. sp. F: dorsal view male holotype; 

G: first male pleopod; H: first antenna. 

Macrostylis abyssicola Hansen 

Figure 27 D-E 

Synonyms: Macrostylis abyssicola Hansen, 1916, pp. 

77-79, PI. VII. 

Diagnosis: Cephalon quadrate. Peraeonal somite 

4 slightly narrower than 3 but not narrower than 5; 

lateral borders rounded slightly. First and second 

peraeonal somites subequal in length. Uropoda as 

long as pleon; peduncle produced at apex and five 

times as long as second article. Dorsum of pleon 

with pits above uropods; plumose setae absent, 

apex produced, convex. Apex male first pleopods 

simple. First antenna with only three articles 

(female). 

129 

Measurements: Female without marsupium 3.1 mm., 

male 2.4 mm. (Hansen, op. cit.). 



3229 meters, temperature 1.4° C, three specimens. 

Distribution: Also collected south of Davis Strait, 

Ingolf Station 38, latitude 59° 12' N., longitude 51° 

05' W., 3521 meters, temperature 1.3° C, about ten 

specimens, and south of Davis Strait at Ingolf Station 

22, latitude 58° 10' N., longitude 48° 25' W., 3474 

meters, temperature 1.4° C, six specimens, and from 

the South Atlantic from L.G.O. Biotrawl No. 23, two 

females, cat. no. 1-120. 

Affinities: The quadrate shape of the cephalon 

distinguishes this species.

130 

Macrostylis setifer, new species 

Figure 27 F-H 



front slightly emarginate. Fourth peraeonal somite 

narrower than third and fifth, lateral borders rounded. 

First peraeonal somite slightly longer than second. 

Uropodal peduncle shorter than width of pleon. 

Dorsum of pleon lacking pits or sensory organs, 


lateral borders not constricted, apex produced, convex, 

with at least 12 plumose setae. Apex of male 

pleopods simple, rounded, lacking stout spines or 

lateral projections, apex with 13 setae. First antenna 

with five articles (male). 






Figure 28. A-D: Macrostylis hirsuticaudts, n. sp. A: dorsal view male holotype; B: first male 

pleopod; C: third paraeopod; D: first antenna. E-G: Macrostylis caribbicus,n. sp. E: dorsal 

view male holotype; F: first pleopod; G: first antenna. H-K: Macrostylis vemae, n. sp. 

H: dorsal view male holotype; I: third paraeopod; J: first pleopod; K: first antenna.

Affinities: The fact that the fourth peraeonal somite 

is narrower than the third and fifth sets this species 

apart from M. caribbicus and M. subinermis. 

Macrostylis hirsuticaudis, new species 

Figure 28 A-D 


Diagnosis: Cephalon narrower in front than 

behind, front straight. Peraeonal somite 4 slightly 

narrower than 3 but as wide as 5, postero-Iateral 

angles sharp, each with a stout seta. First and second 

peraeonal somites subequal in length. Uropodal 

peduncle much longer than length of pleon and twice 

as wide as pleon. Dorsum of pleon with pits in front 

of uropods, sensory organs present, apex almost 

straight bearing at least six plumose setae. Apex of 

male first pleopods laterally without stout spines, 

lateral part recurved, apex with eight setae. First 

antenna with five articles (male). 



pleon 0.6 mm. 


No. 22, types plus two male and two female paratypes, 

cat. no 1-197. 


Affinities: This species is allied to M. longiremis, 

Meinert but has uropoda longer than the pleon not 

shorter. 

Macrostylis caribbicus, new species 

Figure 28 E-G 



behind, front slightly convex. Peraeonal somite 4 as 

wide as 3 and 5, lateral borders rounded. First and 

second peraeonal somites subequal in length. Uropodal 

peduncle not as long as width of pleon. Dorsum 

of pleon without pits or sensory organs, lateral borders 

constricted in front of uropods; apical margin with 16 

plumose setae. Apex of male first pleopods with stout 

spine laterally and five apical setae. First antenna 

with six articles (male). 




Biotrawl No. 98, type, cat. no. 1-118. 


Affinities: This species is close to M. subinermis 

Hansen except that the postero-Iateral angles of the 

cephalon are sharp and pointed, not rounded. 


Macrostylis vemae, new species 

Figure 28 H-K 



behind, front straight. Peraeonal somite 4 as wide as 

3 and 5 and with rounded sides. First and second 

peraeonal somites subequal in length. Uropodal 

peduncle longer than width of pleon. Dorsum of 

pleon without dorsal pits or sensory organs; lateral 

border constricted in front of uropods; apical border 

convex and produced and lacking plumose setae. 

Apex of male first pleopods lacking lateral projections 

or stout spines, each rounded and with eight apical 

setae. First antenna with five articles. 



pleon 0.7 mm. 


No. 231, types and two male and two female paratypes, 

cat. no. 1-110. 


No. 229, one female, cat. no. 1-116. 

Affinities: The bulbous swelling of the pleon in 

front of the uropods distinguishes this from a group of 

species lacking the swollen lateral border. 

Macrostylis bifurcatus, new species 

Figure 29 A-E 


Diagnosis: Cephalon quadrate, front slightly emarginate. 

Peraeonal somite 4 slightly narrower than 3 

but as wide as 5. First and second peraeonal somites 

subequal in length. Peduncle of uropoda longer than 

width of pleon. Dorsum of pleon with slight pits 

above uropods. Apex of male first pleopods without 

stout lateral spine but with spoon-shaped lateral projections 

and each with five apical setae. Pleonal 

lateral margin not constricted in front of uropods. 

First antenna with five articles (male). Apex of pleon 

with deep medial incision; plumose setae lacking. 




No. 51, type, cat. no. 1-188. 



Affinities: The bifurcated nature of the apex of the 

pleon sets this species apart from the others. 

Macrostylis minutus, new species 

Figure 29 F-G 


Diagnosis: Cephalon narrower in front than behind, 

front with three lobes. Peraeonal somite 4 

narrower than 5 but not narrower than 3, lateral 

margins rounded. First peraeonal somite shorter than 

second. Uropodal peduncle as long as pleon. 

Dorsum of pleon with slight pits above uropods and


Figure 29. A-E: Macrostylis bifurcatus, n. sp. A: dorsal view male holotype; B: first antenna; 

C: first paraeopod; D: fourth paraeopod; E: apex of male first pleopod. F-G: Macrostylis 

minutus, n. sp. F: dorsal view female holotype; G: female first antenna. H-M: Macrostylis 

bipunctatus, n. sp. H: dorsal view male holotype; I: third paraeopod; J: first 

paraeopod; K: maxilliped; L: first and second antenna; M: apex first pleopod. 

with sensory organ. Pleonal lateral margin not 

constricted in front of uropods; hind margin produced 

pointed, devoid of plumose setae. First antenna 

with four articles (female). 




No. 234, two female paratypes, cat. no. 1-114. 


No. 231, ten females, cat. no. 1-115, and L.G.O. 

Biotrawl No. 232, one female, cat. no. 1-111. 

Affinities: This species resembles the Pacific M. 

hadalis Wolff except that the first peraeonal somite is 

shorter than the second, rather than longer. 

Macrostylis bipunctatus, new species 

Figure 29 H-M 



front rounded. Peraeonal somite 4 as wide as somites 

3 and 5. First and second peraeonal somites subequal

in length; postero-lateral angles acute. Uropoda 

missing. Dorsum of pleon with pits above uropodal 

insertion. Apex of male first pleopods each with a 

stout recurved spine at lateral margin and six apical 

setae. Apexofpleon devoid of plumose setae. Pleonal 

lateral margin entire, not constricted in front of 

uropods; apical margin convex devoid of plumose 

setae. First antenna with only three articles (male). 


width pleon 0.4 mm., allotype female length 



No. 12, types plus three fragments, cat. no. 1-119. 

Distribution: Taken also from the South Atlantic 

Type genus: Nannoniscus G. O. Sars. 

Diagnosis: Peraeopods not modified (flattened) 

for swimming but with plumose setae. Uropoda with 

peduncle, usually biramous. Peraeonal somites all of 

similar length; first free from cephalon. Maxillipedal 

palp with last two articles narrow; others equal 

width of endite. Dactyl of peraeopods with two 

terminal claws. Molar process of mandible reduced 

to a short setiferous lobe. 

Composition: This family contains Nannoniscus 

Richardson, Austroniscus Vanhoffen, and Nannoniscoid.es 

Hansen. These are distinguished from one another in 

the following key: 


NANNONISCIDAE 

1. First antenna with a bulbous organ 

attached to distal article Nannoniscus 

1. First antenna normal, without bulbous organ . . 2 

2. Last two peraeonal somites incompletely 

fused Nannoniscoides 

2. Last two peraeonal somites entirely 

separated Austroniscus 

The first two genera are represented by abyssal 

species. It is highly probable that Nannoniscella 

Hansen, 1916, is a synonym of Austroniscus 

Vanhoffen, 1914. 

Genus: NANNONISCOIDES Hansen, 1916 

Type species: Nannoniscoides angulatus Hansen, 1916, 

pp. 86-87, PI. VIII. 

Diagnosis: Nannoniscidae with last two peraeonal 

somites incompletely fused. Pleon with single somite. 

Uropoda biramous. First antenna normal, without a 

bulbous organ attached to last article. 

This genus contains only the type, from 702 

fathoms in the North Atlantic, and the new abyssal 

species described herein from the South Atlantic. 


Family: NANNONISCIDAE 

at L.G.O. Biotrawl No. 51, one female, two fragments, 

cat. no. 1-51; L.G.O. Biotrawl No. 52, sixteen specimens, 

cat. no. 1-198; L.G.O. Biotrawl No. 53, one 

male, cat. no. 1-189; and L.G.O. Biotrawl No. 217, 

one female (with statocysts, and perhaps a distinct 

species). 

Affinities: This species is closely allied to M. galatheae 

Wolff, but has the postero-lateral angles of the 

cephalon pointed, not rounded. 

Macrostylis species indeterminable 

Indeterminate species of Macrostylis were taken 

from L.G.O. Biotrawl no. 53, three fragments. 

Nannoniscoides hirsutus, new species 

Figure 30 


Diagnosis: Nannoniscoides, with a laterally serrated 

pleon. Body hirsute and densely reticulate. Cephalon 

three times as broad as the distance between the 

anterior ends of the cephalic keels. Antero-lateral 

angles with a stout seta on second somite, none on 

first or third. First peraeonal somite wider than 

cephalon; last two peraeonal somites pointed at 

lateral border. Uropodal endopod slightly shorter 

than exopod. Antero-lateral processes of cephalon 

not reaching frontal border. Apex of male first 

pleopods with tubular lateral expansion and each 

apex with three setae. 






Affinities: This species may be distinguished from 

N. angulatus Hansen by the fact that the first peraeonal 

somite is wider than the cephalon, not narrower. 

Genus: NANNONISCUS G. O. Sars, 1869 

Type species: Nannoniscus oblongus G. O. Sars 

Synonyms: Nannoniscus G. O. Sars, 1869; — Hansen, 

1916, pp. 87-89. 

Diagnosis: Nannoniscidae with last two peraeonal 

somites incompletely fused. Pleon with a single somite. 

Uropoda biramous. First antenna short, with a bulbous 

organ attached to last article. 

This genus contains 15 described species. Twelve of 

these were desccribed by Hansen (op. cit.); Vanhoffen 

(1914) described two species, and G. O. Sars described 

one.


Figure 30. Nannoniscoideshirsutus, n. sp. A: maxillipedal epipode; B: maxilliped; C: dorsal 

view male holotype; D: mandible; E: first pleopod; F: male second pleopod; G: uropod 

and anus; H: first paraeopod. 

It is impossible at this date to construct a satis- 1- Abdominal operculum of female without tubercle 

factory key to all of the species, and the reader is or P r ° cess on !°wer surface 6 

c J ,.u r , ., f ,1 • i j-r- . C 2. Antero-lateral angles of first peraeonal somite 

referred, therefore, to the tollowinar key modified from . . . a . , r . . . , 

° terminating in a spme, those ol second with a 

Hansen (op. cit.), in which he treats all known species short fine seta simplex Hansen and austraiis VanhofTen 

except austraiis and bidens of VanhofTen. The struc- 2. Antero-lateral angles of first peraeonal somite 

ture of the appendages of these southern species is not without a terminal spine but with or without a fine 

yet known. Here three of Hansens abyssal species, one seta, those of second with a real spine 3 

m r\ o i ji î i _ i • 3. First or second peraeonal somites not one-half 

of Lr. U. bars s, and two apparentfy new abyssal species , , . . , . 

r r J ' r as broad again as sixth somite 4 

are described. 3 Y'vr&t and second peraeonal somites more than 

. „„,, ry,^ rû^ cnrnipc /->T^ one-fialfas broad again as sixth somite . laticeps Hansen 

A rLijY 1U 1 Mill oFr.L«lrjo Ur . , . n . . . , r 

MANMmVTSPTTS 

ri r i-r i r TT ,„,„, 

(Modified from Hansen, 1916) 

Lateral margin ol pleon convex or straight . . . o 

4. Lateral margin of pleon concave just 

., , & „ r , J v ,. „ 

outside base of uropods analis Hansen 

1. Abdominal operculum of female with an acute 5. Antennal squama as long as the diameter of 

process on lower surface 2 third peduncular article . . . . oblongus G. O. Sars

5. Antennal squama shorter than the 

diameter of third peduncular 

article arcticus Hansen 

6. Second article of first antenna with process short, 

leaving the fourth article uncovered 7 

6. Second article of first antenna with long process 

overlapping the fourth article 12 

7. Posterior ventral area of peraeon without any 

process 8 

7. Posterior ventral area of peraeon with one or two 

large recurved acute processes 9 

8. Antennular vesicle two and a half to three 

times as long as broad inermis Hansen 

8. Antennular vesicle pyriform not one-half 

as long again as broad aequiremis Hansen 

9. With only one recurved process 10 

9. With two 

processes armatus Hansen and laevis, n. sp. 

10. Posterolateral margin of pleon without incision 

or tooth 11 

10. Postero-lateral margin of pleon with an 

incision and a conspicuous angle or 

tooth . . . . minutus Hansen and bidens Vanhoffen 

and camayae, n. sp. 

11. First peraeopod without stout setae on inferior 

margin of (fifth article) 

propod plebejus Hansen 

11. First peraeopod with two stout setae 

on inferior margin of (fifth article) 

propod crassipes Hansen 

12. Anterior margin of front of cephalon nearly 

half as wide as cephalon 

width spinicomis Hansen 

12. Anterior margin of front of cephalon less than 

one-half as wide as cephalon affinis Hansen 

LIST OF THE SPECIES OF NANNONISCUS 

Species 

1. oblongus G. O. Sars 

2. simplex Hansen 

3. arcticus Hansen 

4. analis Hansen 

5. laticeps Hansen 

6. reticulatus Hansen 

7. inermis Hansen 

8. aequiremis Hansen 

9. plebejus Hansen 

10. minutus Hansen 

11. armatus Hansen 

12. spinicomis Hansen 

13. a^nis Hansen 

14. australis Vanhoffen 

15. bidens Vanhoffen 

16. caspius G. O. Sars 

17. crassipes Hansen 




225 

1070 

75 

•— 

—• 

— 

— 

— 

— 

— 

— 

— 

— 

— 

— 

Nannoniscus inermis Hansen 

Figure 31 A-C 

1505 

1505 

699 

2258 

552 

552 

2258 

885 

1505 

1096 

3521 

2465 

1505 

385 

385 

intertidal 

?225 468 

Synonyms: Nannoniscus inermis Hansen, 1916, pp. 

98-99, PI. IX. 

Diagnosis: Nannoniscus with cephalon a little more 

than four and a half times as broad as the distance 

oetween the anterior ends of the cephalic keels. 

Antero-lateral angles of first somite of peraeon without 

spine; second and third with spine. Tubercle or process 

lacking from female operculum, which has a 

straight distal margin. Uropodal endopod almost 

twice as long as exopod. Pleon without teeth. 

Measurements: Female with marsupium length 

3.3 mm. 



2258 meters, temperature 2.4° C. (Hansen, op. cit.). 


Affinities: This species seems most nearly related to 

N. aequiremis Hansen, differing from it in having a 

more elongate antennular vesicle. 

Nannoniscus armatus Hansen 

Figure 31 D-E 

Synonyms: Nannoniscus armatus Hansen, 1916, pp. 

102-103, PI. X. 

Diagnosis: Nannoniscus with cephalon four times as 

broad as the distance between the anterior ends of the 

cephalic keels. Antero-lateral angles of first and third 

somites without spines on setae. Tubercle or process 

lacking from female operculum, which has a convex 

distal margin. Uropodal exopod considerably less 

than one-half the length of endopod. Pleon without 

teeth. 

Measurements: Juvenile length 1.6 mm. 



51° 05' W., 3521 meters, temperature 1.3° C. (Hansen, 

op. cit.). 


Affinities: This species is closely related to N. 

laevis, n. sp., differing from it only in having a narrower 

frontal area on the cephalon and blunt lateral 

borders to the seventh peraeonal somite rather than 

angular ones. 

Nannoniscus analis Hansen 

Figure 31 F-H 

Synonyms: Nannoniscus analis Hansen, 1916, pp. 

95-96, PI. VIII-IX. 

Diagnosis: Nannoniscus with cephalon four times 

as broad as the distance between the anterior ends of 

the cephalic keels. Antero-lateral angles of first and 

third somites with no spines but frequently with a 

short seta; second with a distinct long spine. Operculum 

with a highly raised strong acute process. Uropodal 

endopod not twice as long as exopod. Pleon 

without teeth. 

Measurements: Large specimen length 2.6 mm. 



2258 meters, temperature 2.4° C. (Hansen, op. cit.). 


Affinities: The concave nature of the pleonal

136 


Figure 31. A-C: Nannoniscus inermis Hansen. A: anterior left part of head with antennula 

and antenna of female; B: outline of anterior of head of female; C: abdomen and two 

posterior thoracic segments of female. D-E: Nannoniscus armatus Hansen. D: dorsal view 

female; E: dorsal view head of female. F-H: Nannoniscus analis Hansen. F: abdomen of 

male; G: dorsal view of male anterior; H: dorsal view of female. I-K: Nannoniscus oblongus 

G. O. Sars. I: ventral view of uropods, anus, and abdomen of female; J: dorsal view of 

female; K: ventral view of uropods, anus, and abdomen of male. 

lateral margins distinguishes this species from the 

others. 

Nannoniscus oblongus G. O. Sars 

Figure 31 I-K 

Synonyms: Nannoniscus oblongus G. O. Sars, 1870, 

p. 164; —1897, p. 119, PI. 50 (female only); — 

Hansen, 1916, pp. 92-94, PL VIII. 

Diagnosis: Nannoniscus with cephalon as much as 

seven times as broad as the distance between the 

anterior ends of the cephalic keels. Antero-lateral 

angles with stiff spine or seta on first, second, and 

third somites. Operculum with a large medial spine 

and with distal margin semi-circular. Uropodal exopod 

shorter than endopod. Pleon without teeth. 

Measurements: Largest male 2.2 mm. (Hansen, 

op. cit.). 

Type locality: Off the Lofoten Islands, at Skraaven, 

in depths ranging from 225 to 468 meters (Hansen, 

op. cit.). 

Distribution: North Atlantic: Davis Strait, Ingolf 


599 meters, temperature 3.9° C.; west of Iceland, 

Ingolf Station 98, latitude 65° 38' N., longitude 26° 

27' W., 260 meters, temperature 5.9° C.; southwest 

of Iceland, Ingolf Station 78, latitude 60° 37' N.,


Figure 32. A-C: Nannoniscus camayae, n. sp. A: dorsal view female holotype; B: first 

antenna holotype; C: uropod. D-G: Nannoniscus laevis, n. sp. D: dorsal view female 

holotype; E: uropod; F: mandibular molar process; G: first antenna. H-K: Nannoniscus 

primitivus, n. sp. H: dorsal view male holotype; I: uropods; J: first male pleopod; K: first 

antenna. L-M: Nannoniscus spinicornis, Hansen. L: dorsal view anterior; M: Ventral view 

posterior. 


4.5° C. South Atlantic: L.G.O. Biotrawl No. 212, 


Nannoniscus camayae, new species 

Figure 32 A-C 


Diagnosis: Nannoniscus with cephalon three times 


the cephalic keels. Antero-iateral angles of first 

peraeonal somite without spines or setae; second and 

third with setae. Operculum without projected spines 

but with a pair of depressions on either side of midline. 

Fourth article of first antenna extending to one-third 

the length of vesicle. Uropodal exopod one-half the 

length of endopod. Pleon with a single tooth on each 

lateral margin. 






Affinities: Closely related to N. minutus Hansen 

and N. bidens Vanhoffen. It differs from minutus and 

bidens in lacking the stout spine at the antero-iateral 

angle of the first peraeonal somite.


Nannoniscus laevis, new species 

Figure 32 D-G 


Diagnosis: Nannoniscus with cephalon three times 


the cephalic keels. Antero-lateral angles of first 

peraeonal somite with a stout seta; second and third 

with a fine seta. Operculum without projecting spines. 

Peraeon with two stout recurved spines ventrally. 

Fourth article of first antenna extends beyond antennal 

vesicle. Pleon without teeth on lateral margins. 



Type locality: South Atlantic L.G.O. Biotrawl No. 

53, type and three female paratypes, cat. no. 1-125. 


Affinities: The blunt lateral borders of the seventh 

peraeonal somite distinguish this species from its 

nearest relative, N. armatus Hansen. 

Nannoniscus primitivus, new species 

Figure 32 H-K 


Diagnosis: Nannoniscus with cephalon twice as 


cephalic keels. Antero-lateral angles of first peraeonal 

somite sharply pointed but without spines; second 

with stout spine, third with weak seta. Second article 

of first antenna without distal spine-like projections 

and third not extending beyond start of vesicle. 

Uropodal exopod two-thirds the length of endopod. 





Type genus: Eurycope, G. O. Sars. 

Diagnosis: Paraselloidea with peraeopods 5-7 

inclusive paddle-like, modified for swimming and 

bearing dactyls. Cephalon (usually) separated from 

first peraeonal somite. Pleon with one or two somites. 

Uropoda uni-biramous; peduncle not flattened and 

not bearing pulmose setae. 

Composition: This family contains Eurycope, Storthyngura, 

Syneurycope, Munnopsurus, and Acanthocope. 

The genera, except for Munnopsurus, are represented 

in the Atlantic abyss and are distinguished from one 

another in the following key. 

A KEY TO THE GENERA OF THE 

EURYCOPIDAE 

1. Uropoda biramous 2 

1. Uropoda uniramous Acanthocope 

Family: EURYCOPIDAE 


Affinities: This species is unique in the primitive 

structure of the first antenna and its vesicle. The 

spines on the pleon are probably secondary sexual 

characteristics. 

Nannoniscus spinicornis Hansen 

Figure 32 L-M 

Synonyms: Nannoniscus spinicornis Hansen, 1916, 

pp. 104-105, PI. X, Figs. 2a-2g. 

Diagnosis: Nannoniscus with cephalon twice as 


cephalic keels. Antero-lateral angles of the first three 

peraeonal somites only slightly produced, acute, but 

without spines or setae. Second and third articles of 

first antenna with spine-like projections which extend 

to middle of vesicle. Uropodal exopod one-half the 

length of endopod. 

Measurements: Length of female specimen, 1.5 

mm. (Hansen, 1916, p. 104). 

Type locality: North Atlantic, South of Jan Ma yen, 

Ingolf Station 113, latitude 69° 31'N., longitude 

7° 06' W., 2465 meters, temp. —1.0° C, one female 

specimen (Hansen, op. cit.). 


Affinities: This species is close to N. affinis Hansen, 

from which it differs in having a wider frontal area to 

the cephalon. 

Nannoniscus species indeterminable 

Damaged specimens of Nannoniscus were taken from 

L.G.O. Biotrawl No. 16, three specimens, and L.G.O. 

Biotrawl No. 107, one female. 

2. Mandibular incisor reduced to a simple 

single tooth Munnopsurus 

2. Mandibular incisor toothed, normal 3 

3. Pleon with lateral spines Storthyngura 

3. Pleon without lateral spines 4 

4. Inner margin of maxillipedal palp articles 

with denticles Syneurycope 

4. Inner margin of maxillipedal palp articles 

without denticles Eurycope 

A LIST OF THE KNOWN ABYSSAL SPECIES OF 

EURYCOPE 



1. hanseni Ohlin 520 2669 

2. incisa Gurjanova 2380 2380 

3. abyssicola Beddard 3886 3886 

4. complanata Bonnier 950 2702

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

Species 

furcata G. O. Sars, Hansen 

murrayi Walker, Hansen 

nodifrons Hansen (not Wolff, 

1956) 

parva Bonnier, Hansen 

producta G. O. Sars, Hansen, Hult 

scabra Hansen 

spinifrons Gurjanova 

ovalis Vanhoffen 

galatheae Wolff 

vicarius Vanhoffen 

sarsii Beddard 

madseni Wolff 




150 

>1000 

2702 

872 

72 

2486 

308 

3423 

6960 

6960 

Genus: EURYCOPE G. O. Sars 

2258 

>2700 

2702 

2702 

2087 

2486 

3000 

3423 

7000 

3423 

2514 

7000 

Type species: Eurycope cornuta G. O. Sars, 1864, p. 5; 

— 1897, pp. 145-146, PI. 64; — Richardson, 1905, 

p. 491 and references. 

Diagnosis: Eurycopidae without spines on body or 

spine-like extensions on pleon. Frontal area of cephalon 

with pronounced keels dorsally. Uropoda biramous. 

Mandibular incisor and lacinia toothed, 

molar strong, normal, truncate at apex. Pleon with 

one somite only. Maxillipedal palp articles without 

denticles on inner margin. 

Composition: This genus contains 41 species, about 

half of which are abyssal, but the exact number of 

species is uncertain. Some of the earlier species have 

been transferred to Storthyngura, Acanthocope, and 

Munnopsurus, Key characteristics for many of the 

species are not known, and the construction of a 

functional key is therefore impossible at present. The 

majority of the species live in relatively shallow water 

only. 

Additionally, three new species are described herein 

and E. antarctica Vanhoffen is added to the abyssal 

fauna. Beddard's species, sarsii, abyssicola, and 

spinosa, are too imperfectly known to be included in 

this key, and this comment applies also to E. galatheae 

Wolff. It is highly doubtful that E. nodifrons Hansen 

occurs in the Pacific hadal depths as reported by 

Wolff (1956). Differences are clear in the maxilliped, 

shape of the posterior peraeonal somites, and the pleon. 

The specimen should be reexamined. 

A KEY TO THE ABYSSAL SPECIES 

OF EURYCOPE 

1. With peraeonal somites 5-6 fused along midline 2 

1. With peraeonal somites 5-6 entirely separated . . 5 

2. Discrete frontal area lacking from 

cephalon antarctica Vanhoffen 

2. Discrete frontal area present on cephalon . . . . 3 

3. Frontal area very broad, close to one-half the 

width of cephalon 4 

3. Frontal area narrow, less than one-fifth 

the width of cephalon furcata G. O. Sars 

4. Female operculum with recurved spine 

directed toward apex of pleon . . . ovaloides, n. sp. 

4. Female operculum with recurved spine 

directed toward head parva Bonnier 

5. Pleon incised medially at 

apex incisa Gurjanova 

5. Pleon not incised medially 6 

6. Frons of cephalon well defined 8 

6. Frons of cephalon not well defined 7 

7. Pleon ovoid longer than wide . . . . scabra Hansen 

7. Pleon shield-shaped, as wide as 

long nodifrons Hansen 

8. Uropodal exopod one-seventh the 

length of endopod murrayi (Walker) 

8. Uropodal exopod one-third to one-half or more 

than the length of endopod 9 

9. Frons of cephalon with stout spines or seta on 

margin 10 

9. Frons of cephalon without stout setae 13 a 

10. Pleon with a spine on each postero-lateral 

border spinifrons Gurjanova 

10. Pleon without spines at postero-lateral border . . 11 

11. Frontal area with three to five stout setae on each 

side of apex 12 

11. Frontal area with one stout seta on 

each side at apex nodosa, n. sp. 

12. Frontal area with three spines on 

each side of apex gaussi Wolff 

12. Frontal area with five spines on 

each side of apex producta G. O. Sars 

13. Antero-lateral angles of pleon spine-like 

and projecting acutitelson, n. sp. 

13. Antero-lateral angles of pleon not spine-like and 

projecting 14 

14. Apex of frontal area of cephalon around onefifteenth 

the width of the cephalon 15 

14. Apex of frontal area of cephalon around one-third 

the width of the cephalon 16 

15. Apex of frontal area deeply incised with medial 

part concave complanata Bonnier 

15. Apex of frontal area incised but with 

distal part (apical incision) 

straight vicarius Vanhoffen, hanseni Ohlin 

16. Apex of pleon blunt madseni Wolff 

16. Apex of pleon rounded ovalis Vanhoffen 

a Ovalis is placed here due to Wolff's (1956) redescription 

in which setae are not mentioned, even though Vanhoffen 

(1914) showed setae. 

Eurycope antartica Vanhoffen 

Figure 33 A-B 

Synonyms: Eurycope antarctica Vanhoffen, 1914, pp. 

589-590. 

Diagnosis: Eurycope with apex of frontal area 

rounded, around one-third the width of cephalon, 

lacking stout setae. Apex of pleon pointed. Inner 

distal margin of male second pleopod without vermiform 

appendage. Peraeonal somites 5-6 fused along 

midline. Uropodal exopod about one-half the length 

of endopod. 

Measurements: Mature female 3.0 mm. long 

(Vanhoffen, op. cit.). 

Type locality: Antarctic Gauss station, 66° 15' S., 

80° 19' E., 385 meters, 135 specimens (Vanhoffen, 

op. cit.).


Figure 33. A-B: Eurycope antarctica Vanhoffen. A: dorsal view male length 1.8 mm., width 

0.6 mm.; B: apex of first male pleopod. C-F: Eurycope furcata G. O. Sars. C: dorsal view 

female; D: ventral view uropods; E: first and second male pleopods; F: uropods female. 

G—J: Eurycope producta G. O. Sars. G: dorsal view female; H: second antenna; I: first 

antenna; J: first and second male pleopods. 

Distribution: Also taken from South Atlantic 

Ocean, L.G.O. Biotrawl No. 201, three males, three 

females, cat. no. 1-233. 

Eurycope furcata G. O. Sars 

Figure 33 C-F 

Synonyms (incomplete): Eurycope furcata G. O. Sars, 

1870, p. 165; — 1898, p. 148; — Gurjanova, 1933, p. 

425; — Hansen, 1916, p. 151; — Hult, 1941, pp. 

109-110. 


deeply incised without stout setae, about one-tenth 

the width of cephaion. Pleon with acute antero-lateral 

angles, apex evenly rounded, without postero-lateral 

spines. Inner distal margin of male second pleopod 

without vermiform appendage. Peraeonal somites 5-6 

fused along midline. Uropodal exopod slightly shorter 

than endopod. 

Measurements: Adult female scarcely attaining 

2 mm., (G. O. Sars, 1898, p. 149). 

Type locality: Lofoten Islands at Skraaven, 100-200 

fathoms, sandy clay (G. O. Sars, 1898, p. 149). 

Distribution: West coast of Norway to Davis 

Strait and off west coast of Greenland from c. 150 

meters to 2258 meters (Hult, 1941, p. 109). It was 

taken by the Ingolf at two stations (Hansen, 1916, p. 

151): Station 24, Davis Strait, latitude 63° 06' N., 


2.4° C, one specimen; Station 78, southwest of 

Iceland, latitude 60° 37'N., longitude 27° 52'W., 

1505 meters, temperature 4.5° C., two specimens. 

It was not collected by Vema.

Eurycope producta G. O. Sars 

Figure 33 G-J 

Synonyms (incomplete): Eurycope producta G. O. Sars, 

1868, p. 113; — 1898, p. 146; — Gurjanova, 1933; 

p. 424; — 1938, p. 334; — Hansen, 1916, p. 147; 

— Stephensen, 1917, p. 298; — Tattersall, 1905, p. 

75; — Hult, 1941, pp. 107-109. 


convex, without stout setae, about one-fifth the width 

of cephalon. Pleon without spines or incisions, apex 

broadly rounded. Inner distal margin of male second 

pleopod without vermiform appendage. Peraeonal 

somites 5-6 entirely separated. Uropodal rami nearly 

equal in length. 

Measurements: Adult female 3 mm. length (G. O. 

Sars, 1898, p. 146). 

Type locality: Norwegian coast from Christiania 

Fjord to Vadso (G. O. Sars, 1898, p. 146). 

Distribution: Eurybathial arctic-boreal Norway, 

south and east of Greenland, south and southwest of 

Iceland (Hult, op. cit., pp. 108-109). The Ingolf 

collected the species from three stations: Station 

25, Davis Strait, latitude 63° 30' N., longitude 

54° 25' W., 1096 meters, temperature 3.3° C, 

two specimens; Station 78, southwest of Iceland, 


temperature 4.5° C., three specimens; Station 138, 

northwest of the Faeroes, latitude 63° 26' N., longitude 

7° 56' W., 887 meters, temperature —0.6° C., 

one specimen. The maximum depth, according to 

Hult (op. cit.), is 2087 meters and the minimum 72 

meters. It was not collected by Vema. 

Eurycope vicarius Vanhoffen 

Figure 34 A-G 

Synonyms: Eurycope vicarius Vanhoffen, 1914, pp. 

586-587, Figs. 116-117; —Wolff, 1956, pp. 130-132. 


convex, without stout setae, around one-tenth the 

width of cephalon. Pleon without spines or incisions, 

apex rounded. Inner distal margin of male second 

pleopod without vermiform appendage. Peraeonal 

somites 5-6 entirely separated. Uropodal exopod 

about one-third the length of endopod. 

Measurements: 1.6 mm., 2.5 mm., 3 mm., 3.5 mm., 

4.5 mm., and 9 mm. length of six specimens (Vanhoffen, 

op. cit., p. 587). Wolff's (op. cit.) female 

lectotype was 8.8 mm. long and 2.8 mm. wide. 

Type locality: Antarctic continent, 3423 meters, 

3 April 1903, Gauss (Vanhoffen, op. cit.). 

Distribution: Antarctic 3423 meters (Vanhoffen) 

and taken by Vema from the South Atlantic, L.G.O. 

Biotrawl No. 201, seven females, cat. no. 1-234. 

The specimen from Gauss Station at 385 meters has 

been subsequently described as E. gausii by Wolff 

(1956, op. cit.). 


Eurycope complanaia Bonnier 

Figure 34 H-L 

141 

Synonyms: Eurycope complanata Bonnier, 1896, p. 

601, PI. 34; — Hansen, 1916, pp. 145-146, PI. 13. 


lacking spines, apex sharply concave, around oneeleventh 

the width of cephalon. Pleon without 

spines or incisions, apex pointed. Inner distal margin 

of male second pleopod with pronounced vermiform 

appendage. Peraeonal somites 5-6 entirely 

separated. Uropodal exopod one-third shorter than 

endopod. 

Measurements: Male 5 mm. long (Bonnier, op. cit.) 

Type locality: North Atlantic, Bay of Biscay, 



Distribution: North Atlantic. Taken by Ingolf at 

Station 24, Davis Strait, latitude 63° 06' N., longitude 

56° 00' W., 2258 meters, temperature 2.4° C., four 

specimens, and Station 36, Davis Strait, latitude 

61° 50' N., longitude 56° 21' W.,2702 meters, temperature 

1.5° C., two specimens; and by Vema from L.G.O 

Biotrawl No. 7, one male and four fragments, cat. no. 

135. 

Eurycope murrayi Walker 

Figure 34 M 

Synonyms (incomplete): Munnopsis( ?) murrayi 

Walker, 1903, p. 227, PI. 18; — Tattersall, 1905, 

pp. 27, 73; — 1911, p. 190 (ref. Hansen, 1916). 

Munneurycope tjalfiensis Stephensen, 1913, p. 99, Figs. 

6-8; — 1915, p. 23, Figs. 12-13. Eurycope murrayi 

Walker, Hansen, 1916, pp. 137-140, PI. 12. 

Diagnosis: Eurycope with frontal area probably 

obsolete. Pleon without projecting spines or incisions, 

apex rounded. Peraeonal somites 5-6 entirely separated. 

Uropodal exopod around one-tenth the length 

of the endopod. 

Measurements: Length varies from about 7 mm. 

to a little over 8 mm., male (Stephensen, 1915, p. 24). 

Type locality: West of Ireland between 350 and 

1710 fathoms (Hansen, 1916, p. 139). 

Distribution: Taken in the North Atlantic from the 

following places: West of Cape Farewell: Tjalfe, 


wire out, one specimen (Stephensen, 1915). 

South of Iceland: Thor latitude 61° 34' N., longitude 

19° 05' W., 1800 meters wire out, four specimens, 

Thor, latitude 61° 30' N., longitude 17° 08' W., 1800 

meters wire out, fourteen specimens; Thor, latitude 

62°47'N., longitude 10° 03' W., 1500 meters wire 

out, two specimens. 

Southwest of the Faeroes: Thor, latitude 60° 00' N., 

longitude 10° 35' W., 1000 meters wire out, three 

specimens; Thor, latitude 59° 52' N., longitude 

9° 53' W., 1500 meters wire out, five and a half


Figure 34. A-G: Ewycope vicarius Vanhoffen. A: lateral view; B: maxilliped; C: first 

pleopod; D: first pleopod. E: mandible; F: second male pleopod; G: apex of female 

operculum. H-L: Ewycope complanata Bonnier. H: dorsal view male; I: first male pleopod; 

J: uropod; K: maxilliped and maxillipedal epipod; L: second pleopod. M: Ewycope 

murrayi Walker, dorsal view. N: Ewycope parva Bonnier, ventro-lateral view of abdomen. 

specimen (Hansen, 1916, p. 139). Hansen (1916) 

cites other finds. 

This species was not collected by Vema. 

Eurycope parva Bonnier 

Figure 34 N 

Synonyms: Eurycope parva Bonnier, 1896, p. 60, PI. 

33; — Hansen, 1916, pp. 149-150, PI. 13. 

Diagnosis: Eurycope with a broad blunt frontal area 

apex lacking spines and about one-half the width of 

cephalon. Pleon without spine incisions or projections. 

Peraeonal somites 5-6 fused along midline. Female 

operculum with recurved spine directed toward 

cephalon and located at distal end of operculum. 

Uropodal exopod scarcely one-third as long as endopod. 

(After Hansen, op. cit.). 

Measurements: Male 3 mm. long (Hansen, op. cit.). 

Type locality: North Atlantic, Bay of Biscay, 



Distribution: Taken by Ingolf at Station 36, Davis 

Strait, latitude 61° 50' N., longitude 56° 21' W., 2702 

meters, temperature 1.5° C, two specimens; and by 

Thor from southwest of the Faeroes, latitude 61° 15' N., 

longitude 9° 35' W., 872-970 meters, one female 

(Hansen, op. cit.). This species was not captured by 

the Vema.

Eurycope nodifrons Hansen 

Figure 35 A-C 

Synonyms: Eurycope nodifrons Hansen, 1916, pp. 

140-141, PI. 13.? Wolff, 1956, pp. 123-125. 

Diagnosis: Eurycope with obsolete frontal area. 

Pleon without spines or incisions, apex broadly 

rounded. Peraeonal somites 5-6 entirely separated 

(uropoda missing). 

Measurements: Length 5 mm. (Hansen, op. cit. 

p. 140). 

Type locality: North Atlantic, Ingolf Station 36, 

Davis Strait, latitude 61° 50'N., longitude 56° 21' 

W., 2702 meters, temperature 1.5° C, one specimen 



Eurycope hanseni Ohlin 

Figure 35 D-E 

Synonyms: Eurycope hanseni Ohlin, 1901, p. 34, Fig. 

7; — Hansen, 1916, pp. 144-145, PI. 13. 

Diagnosis: Eurycope with frontal area having an 

indented margin, setae lacking, and only about onefifteenth 

the width of cephalon. Pleon without spines 

or incisions, apex broadly rounded. Inner distal 

margin of male second pleopod without vermiform 

appendage. Peraeonal somites 5-6 entirely separated. 

Uropodal exopod almost as long as endopod. 

Measurements: Female length 10 mm. (Hansen, 

op. cit.). 

Type locality: (Probably) North Atlantic, latitude 

77° 52' N., longitude 3° 5' W., 2669 meters: and 

latitude 76° 36' N., longitude 12° 10' E., 1708 meters 


Distribution: Also taken by Ingolf'from Station 105, 

east of Iceland, latitude 65° 34' N., longitude 7° 31' 

W., 1435 meters, temperature —0.8° C, three specimens, 

small; Station 102, east of Iceland, latitude 


—0 9° C, one specimen; Station 113, south of 

Jan Mayen, latitude 69°31'N., longitude 7°06'W., 

2465 meters, temperature — 1 0° C , four specimens; 

Station 118, south of Jan Mayen, latitude 68° 27' N., 


—0.1° C, one specimen (Hansen, op. cit.). This 

species was not captured by the Vema. Gurjanova 

(1946) and Gorbunov (1946) record it from many 

Arctic positions to 2500 meters. 

Eurycope incisa Gurjanova 

Figure 35 F-L 

Synonyms: Eurycope incisa Gurjanova, 1946a, pp. 

278-280, 295, Fig. 10. 

Diagnosis: Eurycope with obsolete frontal area. 

Pleon with deep concave medial incision. Peraeonal 


somites 5-6 entirely separated. Uropodal exopod 

one-third the length of endopod. 

Measurements: Length 10 mm. (?) (Gurjanova, 

op. cit., p. 279). 

r C 

Figure 35. A-C: Eurycope nodifrons Hansen. 

A: dorsal view; B: first pleopod; C: dorsal 

view cephalon. D-E: Eurycope hanseni Ohlin. 

D: ventral view uropods and anus; E: first 

pleopod. F-L: Eurycope incisa Gurjanova. 

F: dorsal view; G: first antenna; H: pleopod; 

I: male operculum; J: female operculum; 

K: uropod; L: peraeopod. 

Type locality: Arctic Ocean, Sadko Station 10, 


(Gurjanova, op. cit. p. 293). 


This species was not taken by Vema. 

Eurycope acutitelson, new species 

Figure 36 A-E 



devoid of spines, about one-sixth the width of cephalon. 

Pleon with antero-lateral angles sharp, spinelike, 

projecting, apex evenly rounded. Inner distal 

angle of male second pleopod without vermiform 

appendage. Peraeonal somites 5-6 entirely separated. 

Uropodal exopod one-half the length of endopod.


Figure 36. A-E: Eurycope acutitelson, n. sp. A: dorsal view male holotype; B second 

pleopod; C: sixth peraeopod; D: lateral view pleotelson; E: male pleopod. F-H: Eurycope 

nodosa, n. sp. F: first antenna; G: dorsal view female holotype; H: uropod. I-J: 

Eurycope ovaloides, n. sp. I: dorsal view gravid female holotype; J: uropod.



pleon 0.9 mm. 


52, types plus six male and six female paratypes, cat. 

no. 1-138. 


Affinities: This species is unique in its sharp 

pleonal antero-lateral borders. 

Eurycope nodosa, new species 

Figure 36 F-H 


Diagnosis: Eurycope with broad frontal apex 

bearing a stout seta on each side and being around oneseventh 

the width of cephalon. Pleon shield-shaped, 

apex evenly rounded, lacking spines or incisions. 

Peraeonal somites 5-6 completely separated. Uropodal 

exopod about one-half the length of endopod. 




53, type and one female paratype, cat. no. 1-137. 


Affinities: This species is allied to gaussi Wolff 

from the Antarctic, from which it differs in having 

fewer setae on the frontal area. 

Eurycope ovaloides, new species 

Figure 36 I-J 


Diagnosis: Eurycope with broad frontal area bearing 

three spines on each side and being around one-half 

the width of cephalon. Pleon without spines or 

projections, apex rounded. Peraeonal somites 5-6 

fused on midline. Uropodal exopod about one-third 

the length of endopod. 

Measurements: Gravid female holotype length 4.3 





Affinities: This species is allied to ovalis Vanhoffen, 

from which it differs in having only three spines on 

either side of the frontal area and in having the frontal 

margin of the frontal area nearly straight and not 

deeply incised. 

Eurycope species indeterminable 

Fragments of Eurycope were common and were 

taken from L.G.O. Biotrawl No. 1, ten fragments; no. 

9, one female fragment; no. 12, three fragments; 

no. 16, several fragments; no. 49, three fragments; 

no. 51, two fragments of two species; no. 52, fourteen 


miscellaneous fragments; no. 53, fifty-two fragments; 

no. 94, two fragments; no. 101, one fragment; no. 

201, four fragments; no. 218, three fragments; no. 

231, four fragments; no. 233, one fragment; no. 234, 

six fragments; no. 237, one female fragment. 

Genus: STORTHYNGURA Vanhoffen 

Synonyms: Storthyngura Vanhoffen, 1914, p. 583; 


Diagnosis: Eurycopidae with biramous uropoda. 

Dorsum of body provided with spines. Pleon laterally 

with spine-like projections. Front of cephalon well 

defined. Last three peraeonal somites immovable but 

usually with indications of separation. Coxal plates 

visible in dorsal view on peraeonal somites 2-4 

inclusive. Pleon separated from peraeon. 

Type species: Storthyngura elegans Vanhoffen, 1914, 

p. 584, Fig. 114. Unfortunately, Vanhoffen (op. cit.) 

did not select a type, and not all of the species cited by 

him actually belong to the genus. 

Composition: Of the 13 species cited by Wolff (1956) 

one does not belong to Storthyngura but belongs instead 

to Acanthocope—viz., A. atlantica (Beddard). This 

error was continued by Birstein (1957). The 18 known 

species are shown in the accompanying list. 

Prior to this monograph only two species, S. 

magnispina (Richardson) and S. truncata (Richardson), 

were known from the abyss of the Atlantic. Six new 

species from the Atlantic abyss are described herein. 

The species range in depth from 400 to 7000 meters. 

A LIST OF THE DESCRIBED SPECIES OF 

STORTHYNGURA 

Species 

1. elegans Vanhoffen 

2. pulchra Hansen 

3. novaezelandiae (Beddard) 

4. magnispinis (Richardson) 

5. truncata (Richardson) 

6. fragilis (Beddard) 

7. benti Wolff 

8. furcata Wolff 

9. caribbea (Benedict) 

10. herculea Birstein 

11. tenuispinis tenuispinis Birstein 

12. tenuispinis kurilica Birstein 

13. brachycephala Birstein 

14. chelata Birstein 

15. bicornis Birstein 

16. vitjazi Birstein 

17. robustissima Monod, Stephensen 

1947 

18. intermedia (Beddard) 



3423 

2490 

2012 

2258 

2788 

2305 

5230 

5850 

1256 

6475 

7246 

7210 

5670 

5345 

6156 

7305 

400 


STORTHYNGURA 

3423 

2690 

2012 

2702 

3225 

2305 

7000 

6770 

1256 

8100 

7246 

7230 

5680 

6860 

6207 

8430 

750 

5670 5670 

1. Pleon with pointed apex 2 

1. Pleon with truncated, rounded, or indented 

apex 9

146 


2. Dorsum of cephalon with spines 3 

2. Dorsum of cephalon without spines 7 

3. Dorsum of pleon with spines 4 

3. Dorsum of pleon without spines 5 

4. Second peraeonal somite dorsally with a transverse 

row of three spines triplispinosa, n. sp. 

4. Dorsum of second peraeonal somite with one 

medial spine 20 

5. Cephalon with three dorsal spines 6 

5. Cephalon with two dorsal spines . . bicornis Birstein' 

6. Second peraeonal somite with two spines 

in row at midline pulchra (Hansen) 

6. Second peraeonal somite with one 

medial spine chelata Birstein 

7. Dorsum of pleon with spine 8 

7. Dorsum of pleon without 

spine novaezelandiae (Beddard) 

8. Dorsum of 3^1 peraeonal somites each with 

one medial spine symmetrica, n. sp. 

8. Dorsum of 3-4 peraeonal somites each 

with two spines in longitudinal 

row caribbea (Benedict) 

9. Dorsum of cephalon with spines 10 


10. Apex of pleon indented vemae, n. sp. 

10. Apex of pleon rounded digitata, n. sp. 

11. Apex of pleon incised medially 12 

11. Apex of pleon truncated or rounded, not incised 

medially 14 

12. Dorsum of pleon without spines . . elegans Vanhoffen 


13. With one spine furcata Wolff 

13. With three spines 21 


14. Dorsum of pleon without spines 17 

15. With three or more spines 16 

15. With one or two spines 18 

16. With three spines . . . . tenuispinis kurillica Birstein 

16. With four spines . . . . tenuispinis tenuispinis Birstein 

17. Lateral spines peraeon longer than wide . . . . 22 

17. Lateral spines peraeon broader 

than long herculea Birstein 

18. With two spines on pleon dorsum 19 

18. With one spine on pleon dorsum . . birsteini, n. sp. 

19. Apex of pleon rounded snanoi, n. sp. 

19. Apex of pleon straight . . . . truncata (Richardson) 

20. Dorsum of pleon with three spines in 

longitudinal row robustissima Monod 

20. Dorsum of pleon with two spines in 

longitudinal row benti Wolff 

21. Spines at pleonal apex sharp . . brachycephala Birstein 

21. Spines at pleonal apex 

blunt magnispinis (Richardson) 

22. Apex of pleon straight vitjazi Birstein 

22. Apex of pleon evenly 

rounded intermedia (Beddard) 

Storthyngura digitata, new species 

Figure 37 A-C 


Diagnosis: Storthyngura with spines on dorsum of 

cephalon and pleon. Cephalon with four spines, two 

on each side of midline. Peraeonal somites 1-4 each 

with a transverse row of three spines, somites 5-7 with 

transverse row of two spines. Pleon with four spines; 

lateral border spinulate, apical border rounded, 

spinulate. Uropodal exopod one-half the width of 

endopod and two-thirds as long as endopod. Endopod 

longer than peduncle. Spine of body not tapering, 

as wide at distal as proximal end. 






Affinities: This species is related to S. vemae, but the 

blunt nature of the body spines makes it distinctive. 

Storthyngura truncata (Richardson) 

Figure 37 D 

Synonyms: Eurycope truncata Richardson, 1908a, 

pp. 67-69, Fig. 1; — Richardson, 1908b, p. 84, Fig. 

20, Storthyngura truncata (Richardson), Vanhoffen, 

1914. 

Description: "Body oblong-ovate, a little more than 

twice as long as wide. Dorsal surface smooth. 

"The head is wider than long, and is produced 

anteriorly in a truncate process which extends between 

the basal articles of the first pair of antennae. On 

either side of the median process there is a slight 

double emargination. The eyes are wanting. The 

first pair of antennae have the basal article large and 

dilated. There is a large and conspicuous spine on the 

inner margin. The second and third articles are small 

and feeble, and of equal length. The flagellum extends 

to the end of the fourth article of the peduncle of 

the second antennae, and is composed of about 

seven articles. The second antennae have the basal 

article short and furnished with a long, conspicuous 

spine on the outer margin. The second article is about 

twice as long as the first, and is furnished on the 

anterior margin with one long spine. The third 

article is about as long as the second, and has two 

spines, one on the outer and one on the inner margin. 

The fourth article is short, and is not furnished with 

any spines. The last two articles of the peduncle and 

the flagellum are missing. The mandibles have a well 

developed palp and molar process. 

"The first four segments of the thorax are about 

equal in length. The antero-lateral angles of the 

first segment are drawn out on either side in one long, 

sharp epimeral spine. The lateral margins of the 

second segment are drawn out on either side in one 

long, sharp spine and one small spine just back of it, 

both epimeral. The lateral margins of the third and 

fourth segments are produced on either side in three 

spines, two small spines and one long, sharp median 

one, a little curved anteriorly. The last two spines are 

epimeral. The last three segments have the lateral 

margins produced on either side in one long, sharp 

spine directed anteriorly. The fifth and sixth segments

are of nearly equal length in the median dorsal line. 

The seventh segment is nearly twice as long as either 

of the preceding segments. 

"The abdomen is composed of one segment. Near 

the base of the segment the lateral margin is produced 

on either side in one long, sharp spine directed anteriorly. 

Below these spines the lateral margins are 

almost straight to about the middle of the segment, 

where there is an abrupt indentation on either side. 

This indentation is followed by two long, sharp 

spines, one on either side, directed posteriorly. 

Below these two spines the lateral margins slightly 

converge to a truncate extremity. Just within the 

two indentations of the lateral margin are indications 

of two tiny tubercles on the dorsal surface. The uropods 

are placed on either side of the truncate extremity 

just below the second lateral spine. They are 

small and feeble and consist of a basal article and two 

branches of nearly equal length. 

"All the four anterior pairs of legs are missing. 

The three posterior pairs are similar, natatory, with 

the merus much enlarged and both the merus and 

propodus furnished with long, plumose hairs. 

"The operculum of the female is furnished with a 

small spine about the middle." (Richardson, 1908a.) 


Type locality: North Atlantic, off Martha's Vineyard, 

U.S. Bureau Fish. Albatross, 1525 fathoms 

(2788 meters) (Richardson, op. cit.). 

Distribution: North Atlantic, off Martha's Vineyard, 

2788 meters (Richardson, 1908a, p. 69); southeast 

of Georges Bank (Richardson, 1908a); and 

Albatross Station 2572, off Georges Bank, 3225 meters 

(Richardson, 1908b, p. 84). 

Affinities: This species is most closely related to 

the Atlantic S. snanoi described later, but it differs in 

having the pleonal apex markedly produced beyond 

the postero-lateral angles. 

Storthyngura magnispinis (Richardson) 

Figure 37 E 

Synonyms: Eurycope magnispinis Richardson, 1908b, 

pp. 84-86, Fig. 21; — Hansen, 1916, pp. 132-134, PL 

12, Figs. 3a-n. 

Description: "Body oblong-ovate, about twice as 

long as wide. Head with the front produced in the 

middle in a rostrum with the extremity truncate and 

the sides incurved; on either side of the rostrum the 

frontal margin has a double excavation; the anterolateral 

angles are acute. The eyes are absent. The 

first pair of antennae have the basal article large 

and armed with one long spine; the two following 

articles are subequal in length and are small; the 

flagellum is lost in the only specimen. The first article 

of the peduncle of the second antennae is short, and 

is furnished on the outer margin with a single spine; 


the second article is a little longer than the first and is 

unarmed; the third article is a little longer than the 

second and is armed with two spines, one on the outer 

and one on the inner margin; the antennae are 

broken at the end of the fourth article. 

Figure 37. A-C: Storthyngura digitata, n. sp. 

A: dorsal view female holotype; B: sixth 

peraeopod; C: uropod. D: Storthyngura 

truncata (Richardson), dorsal view. E: Storthyngura 

magnispinis (Richardson), dorsal view. 

"The first segment of the thorax has the anterolateral 

angles produced in one long spine on either 

side, directed anteriorly; the second segment has the 

lateral margin produced in one long anterior spine 

directed anteriorly and one small posterior one on 

either side; the third and fourth segments have the 

lateral margin produced on either side in three spines, 

two small ones on either side of one long one directed 

anteriorly; the last three segments have the lateral 

margins produced on either side in a single long spine, 

directed anteriorly in the fifth and sixth segments and 

a little posteriorly in the seventh segment. 

"The abdomen has the lateral margin produced on 

either side at the base in one long spine directed a 

little posteriorly; below these spines, the lateral 

margins are nearly parallel to about the middle of the 

segment, where there is an abrupt incision; below 

this incision is a single long spine, directed posteriorly;

148 

below these spines the lateral margins of the segment 

converge slightly to a truncate extremity. The uropoda 

have the basal article short; the inner branch is about 

twice as long as the basal article; the outer branch is a 

little more than half the length of the inner branch. 

"The first four segments of the thorax are each 

armed on the dorsal surface in the median longitudinal 

line with a single spine on the anterior margin, the 

spine on the fourth segment being the longest and 

very prominent; on the three following segments 

there are two long spines, one on each side of the 

median longitudinal line on each segment, those on 

the sixth and seventh segments being nearer the 

middle transverse line of the segment. The abdomen 


has one long median spine near the base, and two 

rudimentary spines or tubercles on the dorsal surface, 

just opposite the incisions in the lateral margins." 

(Richardson, 1908b.) 


Type locality: Off Nantucket Shoals, U.S. Bureau 

Fish. Albatross, Station 2043, 2680 meters. 

Distribution: North Atlantic, off Nantucket Shoals 

(Richardson, 1908b). Ingolf Station 24, 2258 meters. 

See also Hanson (1916). 

Affinities: This species appears to be related to the 

Pacific species S. brachycephala Birstein, from which it 

differs in having the apical pleonal spines blunt 

(almost not spines at all) rather than sharp. 

Figure 38. A-E: Storthyngura triplispinosa, n. sp. A: dorsal view female holotype; B: first 

peraeopod; C: uropod; D: apex of male pleopod; E: first antenna. F-I: Storthyngura 

symmetrica, n. sp. F: first antenna; G second male pleopod; Ff: dorsal view male holotype; 

I: first male pleopod.

Storthyngura triplispinosa, new species 

Figure 38 A-E 



cephalon and pleon. Cephalon with two spines, one 

on either side of midline. Peraeonal somites 1-4 

with three spines in transverse row, somites 5-7 

each with two spines in transverse row. Pleon with 

four dorsal spines and six lateral spines, apex pointed, 

terminating in a long spine. Uropodal exopod as 

wide as endopod and two-thirds its length, peduncle 

as long as endopod. Spines of body tapering to a 

point. 



Type locality: South Atlantic, L.G.O. Bio trawl 


Distribution: Also found in L.G.O. Biotrawl No. 

14, one female, cat. no. 1-240; L.G.O. Biotrawl No. 

53, fourteen females, one male, cat. no. 1-150; 

and L.G.O. Biotrawl No. 212, one male, one female, 

cat. no. 1-144. 

Affinities: The transverse row of three spines on the 

dorsum of the second peraeonal somite distinguishes 

this species from the others. 

Storthyngura symmetrica, new species 

Figure 38 F-I 


Diagnosis: Storthyngura without spines on dorsum 

of cephalon but with spines on dorsum of pleon. 

Pleonal somites 1—4 each with an antero-medial spine, 

somites 5-7 each with a pair of spines. Pleon with 

three spines, lateral border with four spines, apex 

pointed and recurved under pleon; postero-lateral 

spines broader than long, antero-lateral spines 

directed toward cephalon. 



pleon 5.5 mm. 


53, types plus two male and five female paratypes, 

cat. no. 1-146. 


Affinities: The short wide postero-lateral spines on 

the pleon distinguish this species from the group of 

species bearing spines on the body and pleon. 

Storthyngura vemae, new species 

Figure 39 



cephalon and pleon. Dorsum of cephalon with a 

spine on either side of midline. Dorsum of pleon with 


three spines. Peraeonal somites 1-4 each with a 

single spine antero-medially, somites 5-7 each with a 

pair of spines medially. Pleon with four lateral blunt 

spines, apex bilobed and spinulate at margin. Uropodal 

endopod widest at distal end and longer than 

peduncle. Lateral projections of body blunt. 



Type locality: North Atlantic, L.G.O. Biotrawl No. 

9, type plus one fragmentary paratype, cat. no. 1-148. 


Affinities: This species resembles S. digitata, but 

has pointed rather than blunt spines and the apex of 

the pleon is convex rather than rounded. 

Storthyngura birsteini, new species 

Figure 40 A-B 



peraeon and pleon, none on cephalon. Peraeonal 

somites 2-A each with a single dorsal spine at midline 

of anterior margin; somites 5-7 each with a pair of 

dorsal spines at midline. Pleon with a single spine on 

mid-dorsal line of anterior part. Apex of pleon broadly 

rounded, not produced beyond the sharp posterolateral 

angles. Uropodal exopod and endopod about 

equal in width, exopod one-third shorter than endopod, 

which is equal to peduncle in length. 


width pleon 7.8 mm., and one juvenile female paratype 

and three fragments. 


202, types only, cat. no 1-230. 


Affinities: The absence of spines from the dorsum 

of the cephalon and the rounded pleonal apex ally 

this species to S. truncata Richardson, from which it 

differs significantly in the presence of dorsal spines on 

the body and of one dorsal spine not two, on the pleon. 

Storthyngura snanoi, new species 

Figure 40 C-E 


Diagnosis: Storthyngura without spines on dorsum 

of cephalon and with a pair of spines on dorsum of 

pleon. Peraeonal somites 1-4 each with an anteromedial 

spine, somite 5 with a pair of spines, somites 

6-7 without spines. Pleon with four lateral projections, 

apex evenly rounded, not extending beyond uropods. 

Uropodal endopod widest at distal end; it is twice the 

length of exopod and is longer than peduncle. 




Biotrawl No. 95, type only, cat. no. 1-145.


Figure 39. Storthyngura vemae, n. sp. A: dorsal view male holotype; B: sixth peraeopod; 

C: uropod; D: first antenna; E: third pleopod; F: first peraeopod; G: second 

pleopod; H: maxilliped; I: maxillipedal epipod; J: first pleopod; K: ventral view anus 

and uropod; L: mandible. 


Affinities: This species is close to S. truncata 

Richardson, from which it differs in having the pleonal 

apex rounded, not straight. 

Storthyngura species indeterminable 

Fragments of Storthyngura were taken from L.G.O. 

Biotrawl No. 47, one female fragment, and L.G.O. 

Bio trawl No. 214 one juvenile related to S. symmetrica. 

Genus: SYNEURYCOPE Hansen 

Synonyms: Syneurycope Hansen, 1916, pp. 130- 

131; —Menzies, 1956a, pp. 5-6; Ilychthonos Barnard, 

1920, pp. 414-415. 

Diagnosis: Eurycopidae with pleon consisting of 

(one? or) two somites. Last three peraeonal somites 

fused into a solid piece. Uropoda biramous. Coxal 

plates visible in dorsal view on peraeonal somites 2-4 

inclusive. Third article of maxillipedal palp with 

characteristic denticles along inner margin. Lateral 

border of pleon without spine-like extensions. 

(Modified from Menzies, 1956a, p. 5, with corrections.) 

Type species: Syneurycope parallela Hansen, 1916, pp. 

131-132. 

Composition: The species belonging to this genus 

are all markedly attenuate. Three described species 

are known from bathyal to abyssal depths. 

parallela Hansen 3474 meters 

hanseni Menzies 5104-5122 meters 

capensis Barnard 1280 meters

Here two additional new abyssal species are de 

scribed from the South Atlantic abyss. 

Figure 40. A—B: Storthyngura birsteini, n. sp. 

A: dorsal view female holotype; B: uropod. 

C-E: Storthyngura snanoi, n. sp. C: first antenna; 

D: uropod; E: dorsal view female holotype. 

A KEY TO THE SPECIES OF SYNEURYCOPE 

(Modified from Menzies, 1956a, p. 6) 

1. Dorsum of cephalon with spines . . . multispina, n. sp. 


2. Mandibular palp small, unarmed 4 

2. Mandibular palp well developed with 3-4 setae on 

apical article 3 

3. Maxilliped with coupling hooks . . parallela Hansen 

3. Maxilliped without coupling 

hooks hanseni Menzies 

4. First peraeonal somite fused with 

cephalon heezeni, n. sp. 

4. First peraeonal somite separated from 

cephalon capensis (Barnard) 

Syneurycope heezeni, new species 

Figure 41 A-E 


Diagnosis: Syneurycope with cephalon and first 


peraeonal somite fused. Dorsum of cephalon smooth, 

frontal margin between first antennae concave. 

Maxilliped without coupling hooks. Mandibular 

palp without setae on apical article. Fifth peraeopods 

with paddle-shaped terminal articles. Exopod of 

uropod one-fourth as long as endopod. First pleonal 

somite completely separated from pleon. 




200, types and one female paratype, cat. no. 1-227. 

Distribution: Found also at L.G.O. Biotrawl No. 

201, two females, two fragments, cat. no. 1-229, 

and L.G.O. Biotrawl No. 220, one female, cat. no. 

1-228. 

Affinities:' This species is unique in having the 

cephalon fused with the first peraeonal somite. 

Syneurycope parallela Hansen 

Figure 41 F 

Synonyms: Syneurycope parallela Hansen, 1916, pp. 

131-132, PI. 12. 

Diagnosis: Syneurycope without spines on dorsum of 

head. First pleonal somite clearly separated from 

pleotelson. Maxilliped with three coupling hooks. 

Uropodal exopod one-fifth the length of endopod. 

Measurements: Length female 3.7 mm. (Hansen, 

op. cit. p. 131). 

Type locality: North Atlantic, southwest of Cape 

Farewell, Ingolf Station 22, latitude 58° 10' N., longitude 

48° 25' W., 3474 meters, temperature 1.4° C., 

one specimen (Hansen, op. cit.). 


Affinities: Related to S. hanseni Menzies but with 

coupling hooks on the maxilliped. 

Syneurycope hanseni Menzies 

Figure 42 A-D 

Synonyms: Syneurycope hanseni Menzies, 1956a, pp. 

6-7, Fig. 2. 

Diagnosis: Syneurycope without spines on dorsum of 

cephalon. First pleonal somite incompletely separated 

from pleon. Maxilliped without coupling hooks. 

Uropodal exopod one-third the length of endopod. 

Mandibular palp well developed, terminal article 

setiferous. Outer lobe at apex of male first pleopod 

longer than inner lobe. 

Measurements: Male length 3.75 mm., width 

second peraeonal somite 0.65 mm. 


No. 1, type only, cat. no. 11758 A.M.N.H. 


Affinities: This species is related to S. parallela 

Hansen, from which it differs in lacking coupling 

hooks.

Figure 41. A-E: 

C: uropod; D: 

male. 

Syneurycope multispina, new species 

Figure 42 E-K 


Diagnosis: Syneurycope with a row of four to six spines 

in longitudinal row on either side of midline of dorsum 

of cephalon. First pleonal somite completely separated 

from pleotelson. Maxilliped without coupling hooks. 

Mandibular palp well developed, apical article setiferous. 

Outer lobe at apex of male first pleopod 

shorter than inner lobe. 


width pleon 0.6 mm., female allotype length 4.2 mm., 



No. 52, types plus one female paratype. 


Affinities: This species is unique in having spines 

on the dorsum of the cephalon. 


Syneurycope heezeni, n. sp. A: dorsal view female holotype; B: mandible; 

maxilliped; E: gnathopod. F: Syneurycope parallela Hansen, dorsal view 

Genus: ACANTHOCOPE Beddard 

Synonyms: Acanthocope Beddard, 1885, p. 922; — 

Beddard, 1886, pp. 78-79; — Menzies, 1956a, p. 2. 

Diagnosis: Eurycopidae with uniramous uropoda. 

Dorsum of body spinous. Pleon with lateral spine-like 

projections. Front of cephalon well defined. Last 

three peraeonal somites immovable. Pleon with a 

single somite. Coxal plates not visible in dorsal view 

on peraeonal somites 2-4 inclusive. Pleon completely 

fused with peraeon. 

Type species: Acanthocope spinicauda Beddard. 

Composition: Four species are known from Acanthocope. 

These are as follows: 

Species 

1. spinicauda Beddard 

2. acutispina Beddard 

3. atlantica (Beddard) 

4. spinosissima Menzies 



3290 

2650 

1646 

1169 

3290 

2650 

1646 

1169


Figure 42. A-D: Syneurycope hanseni Menzies. A: dorsal view male; B: maxilliped; C: first 

pleopod; D: second pleopod. E-K: Syneurycope multispina, n. sp. E: apex of pleotelson; 

F: apex of first male pleopod; G: maxilliped; H: second pleopod; I: first antenna; 

J: dorsal view male holotype; K: mandible. 

The genus ranges from 1169 meters to 3290 meters. 2. Pleon with dorsal spine(s) 3 

Only two species were known previously from the 2 - Pleon without dorsal spine(s) 4 

A ., . , -. , , ,. . , 3. Pleon with one dorsal spine . . . sbimcauda Beddard 

Atlantic; none was abyssal. Here three additional 3 pleon wkh two dorsa, spines at[antka (Beddard) 

new species are described. 4_ p;rst three peraeonal somites dorsally each with a 

median spine 5 

A KEY TO THE SPECIES OF ^. Fi rs t three peraeonal somites dorsally without 

ACANTHOCOPE s ines 

P 

5. Flagellum of first antenna with over 

6 

1. Body with dorsal spines 2 20 articles. Frons of cephalon 

1. Body without dorsal spines . . . . acutispina Beddard convex annulatus, n. sp.


Figure 43. Acanthocope argentinae, n. sp. A: dorsal view female holotype; B: anus and 

uropods; C: second peraeopod; D: mandible; E: seventh peraeopod; F: maxilliped; 

G: maxillipedal epipod; H: first antenna. 

5. Flagellum of first antenna with six Diagnosis: Gephalon and pleon lacking dorsal 

articles. Frons of cephalon concave on spines. Single short medial spine on dorsum peraeonal 

margin . . . . . . . . . . . . . .. arg inae, n. sp. somites ]_4 inclusive, fifth with a pair of spines. 

o. fourth peraeonal somite dorsally with long . . r 

medial spine unicornis, n. sp. Flagellum of first antenna with five articles only. 

6. Fourth peraeonal somite dorsally Measurements: Female holotype length 3.6 mm., 

without spine spinosissima Menzies width pleotelson 1.5 mm. 


Acanthocope argentinae, new species N a l2, type only, cat. no. 1-155. 

.Figure 4J Distribution: Known only from type locality. 

Synonyms: None. Affinities: This species is closest to A. annulatus,

from which it differs in having the frons of the 

cephalon concave. 

Acanthocope unicornis, new species 

Figure 44 A 


Diagnosis: Acanthocope without spines on dorsum 

of cephalon or pleon. Only fourth peraeonal somite 

with dorsal spine at midline extending as far as the 

frons of cephalon. Flagellum of first antenna with 

four articles only. 






Affinities: Related to A. spinosissima, from which it 

differs in having a long spine on the fourth peraeonal 

somite. 

Acanthocope annulatus, new species 

Figure 44 B-G 


Diagnosis: Acanthocope lacking spines from dorsum 

of cephalon and pleon. First four peraeonal somites 

each with a short medial spine dorsally, fifth with a 

pair of spines dorsally at midline. Flagellum of first 

antenna with over 20 articles. Lateral border of 

cephalon sharply spinulate. 






Affinities: Closest to A. argentinae, from which it 

differs in having the frons of the cephalon convex. 

Type genus: Ilyarachna G. O. Sars. 

Synonyms: Mesostenus G. O. Sars, 1864, p. 211. 

Ilyarachna G. O. Sars, 1869, p. 44; — 1899, p. 134; 

— Hansen, 1916, p. 121; — Hult, 1936, p. 12, — 

Wolff, 1956, p. 106. Aspidarachna G. O. Sars, 1899, 

p. 140; —Hansen, 1916, p. 121; —Hult, 1936, p. 12. 

EchinozoneG. O. Sars, 1899, p. 139; —Hansen, 1916, 

p. 128; —Hult, 1936, p. 12. (incomplete list). 

Diagnosis: Paraselloidea with only peraeopods 

5-6 inclusive paddle-like. Peraeopods 7 walking legs. 

Pleon with one or two somites. Cephalon with first 

antennae not separated by a pronounced frontal area. 

Mandible with reduced setiferous molar; incisor 

reduced to a simple lobe. Uropoda with flattened 

ABYSSAL ATLANTIC ISOPO DS 155 

Family: ILYARACHNIDAE 

Figure 44. A: Acanthocope unicornis, n. sp., 

dorsal view female holotype. B-C: Acanthocope 

annulatus, n. sp. B: dorsal view female holotype; 

C: first antenna. 

Acanthocope species indeterminable 

Fragments of Acanthocope were collected from L.G.O. 

Biotrawl No. 18, two females; No. 94, two females; 

and No. 96, one female. 

peduncle bearing plumose setae. Uropoda unibiramous. 

Composition: The family contains two presently 

recognized genera, Ilyarachna G. O. Sars and Pseudarachna 

G. O. Sars. 

In Pseudarachna the mandible lacks a palp and the 

uropoda are uniramous and only the fifth pair of 

peraeopods is paddle-like (Vanhoffen, 1914, p. 593); 

no abyssal species are known. In Ilyarachna a mandibular 

palp is present, the uropoda are uni-biramous, 

and the 5-6 pair of peraeopods are paddle-like; there 

are several abyssal species. 

Because so many species of Ilyarachna are imperfectly 

known, it is impossible at present to draw up a key

156 

LIST OF ILYARACHNA SPECIES 

Species 

1. abyssorum Richardson 

2. affinis Barnard 

3. crassiceps Barnard 

4. antarctica Vanhoffen 

5. aries (Vanhoffen) 

6. magnified (Vanhoffen) 

7. arctica (Hansen) 

8. bicornis Hansen 

9. dubia Hansen 

10. spinosissima Hansen 

11. bergendali Ohlin 

12. longicornis G. O. Sars, Hult 

13. clypeata G. O. Sars 

14. coronata G. O. Sars 

15. quadrispinosa Beddard 

16. starokadmoskii Gurjanova 

17. zachsi Gurjanova 

18. fusiformis (Barnard) 

19. derjugini Gurjanova 

20. acarina Menzies and Barnard 




4060 

1280 

1280 

252 

385 

350 

103 

2702 

1666 

2702 

21 

18 

216 

188 

22 

130 

105 

1280 

2500 

73 

4165 

1280 

1280 

3423 

385 

385 

103 

2702 

1902 

3521 

698 

2788 

450 

1505 

360 

780 

780 

1280 

2500 

1118 

to_the species. Nevertheless, it may be useful to 

provide the following groupings of species on the basis 

of uropodal structure. 

A. Uropoda 

uniramous 

1. longicornis 

2. denticulata 

3. spinosissima 

4. antarctica 

5. bicornis 

6. dubia 

7. zachsi 

B. Uropoda C. Structure of 

biramous uropoda unknown 

1. coronata 1. crassiceps 

2. clypeata 2. affinis 

3. arctica 3. bergendali 

4. magnifica 4. starokadmoskii 

5. aries 5. derjugini 

6. quadrispinosa 

7. abyssorum 

Only five of the species were known from abyssal 

depths of the Atlantic and Arctic: 

1. abyssorum 

2. bicornis 

3. spinosissima 

4. longicornis (auct. hirtceps?) 

5. derjugini 

Genus: ILYARACHNA G. O. Sars 

Ilyarachna abyssorum Richardson, 1911 

Figure: None available 


Diagnosis: Ilyarachna with "corps oblong-ovale 

environ trois fois plus long que large, 4 millim. 

5x13 millimetres. 

"Tete trois fois plus large que longue, 1 millimetre 

X 3 millimetres; ses angles anterieurs lateraux sont 

arrondis et ne forment pas saillie; les parties laterales 

de la tete ne sont pas dilatees. Yeux absents. Les 

antennes de la premiere paire ont l'article basal large 

et dilate, avec le bord externe lateral recourbe en 

dehors et Tangle externe antero-lateral saillant au 

dela de Tangle interne; les second et troisieme articles 

sont petits et etroits, le deuxieme etant un peu plus 

court que le troisieme; le flagellum se compose de 

onze articles. Les antennes de la deuxieme paire sont 

cassees au bout du quatrieme article. Les mandibules 

n'ont pas de palpe. 

"Les quatre premiers segments du thorax sont 

courts et subegaux comme longueur, chacun d'eux 

ayant environ 1 millimetre; les trois segments qui 

suivent sont plus larges et croissent graduellement en 

longueur ;le cinquieme a 1 millim. 5 de long, le sixieme 

1 millim. 7 5 et le septieme 2 millimetres. Les epimeres 

sont presents sur les quatre premiers segments; 

ils s'etendent sur Tentiere longueur du bord lateral 

dans les trois premiers; leurs extremites anterieures 

sont tres aigues et forment des processus qui depassent 

le bord anterieur des segments; ils semblent partages 

en deux parts dont Tune est anterieure et Tautre 

posterieure. Les epimeres du quatrieme segment 

occupent les deux tiers posterieurs du bord lateral; ils 

sont aigus a leurs extremites anterieures. 

"L'abdomen se compose de deux segments, Tun 

anterieur court, Tautre terminal large, de forme 

triangulaire, avec Tapex arrondi. L'abdomen mesure 

3 millimetres de long et 3 millimetres de large a la base. 

Les uropodes consistent en un article basilaire et en 

deux branches placees pres du bord externe lateral 

du pedoncule; ces dernieres sont situees a quelque 

distance de Textremite; la branche interne est 

posterieure a la branche externe et plus grande 

quoique ne depassant pas Textremite du pedoncule; la 

branche externe est menue." (Richardson, 1911, 

pp. 533-4). 

Three specimens collected by Talisman, 25 August 

1883, Station 135, 4165 meters; two fragments, 

24 August 1883, Station 134, 4060 meters, Azores. 

Not collected by Vema. 

Ilyarachna bicornis Hansen 

Figure 45 A 

Synonyms: Ilyarachna bicornis Hansen, 1916, p. 125, 

PI. 11. 

Diagnosis: Ilyarachna with uniramous uropoda. 

Cephalon with a pair of dorsal spines. Proximal 

margins of peraeonal somites 1-4 inclusive spinulate. 

Pleon with two somites. (From Hansen, op. cit.) 

Measurements: Largest specimen 8.7 mm. (Hansen, 

op. cit.). 



2702 meters, temperature 1.5° C., two specimens. 


Affinities: Hansen (op. cit.) indicated that this 

species was close to /. hirticeps but differed in head 

spines.


Figure 45. A: Ilyarachna bicornis Hansen, dorsal view female anterior. B-D: Ilyarachna 

spinosissima Hansen. B: female uropod; C: dorsal view male; D: dorsal view posterior. 

E-H: Ilyarachna longicornis G. O. Sars. E: male first antenna; F: uropod; G: female first 

antenna; H: dorsal view female. I: Ilyarachna derjugini Gurjanova, second peraeonal somite 

lateral margin (after Gurjanova, 1946a). 

Ilyarachna spinosissima Hansen 

Figure 45 B-D 

Synonyms: Ilyarachna spinosissima Hansen, 1916, 

pp. 127-128, Pis. 11, 12. 

Diagnosis: Ilyarachna with uniramous uropods. 

Cephalon with about 14 spines dorsally. Peraeonal 

somites 1-4 inclusive with denticles on distal margin, 

dorsum with a pair of stout spines on somites 1-3 

inclusive, with four spines on fourth somite. Lateral 

borders of somites 5-7 with stout spines; pleon with 

lateral and dorsal spines; pleon with two somites. 



2702 meters, temperature 1.5° C, one male, one 

female (Hansen, op. cit.). 

Distribution: Taken also from Ingolf Station 38, 

south of Davis Strait, latitude 59° 12' N., longitude 

51° 05' W., 3521 meters, temperature 1.3° C. 

157 

Affinities: This species is close to /. multispinosa, from 

which it differs in having fewer spines on the pleon 

and at the lateral peraeonal margins. 

Ilyarachna longicornis G. O. Sars 

Figure 45 E-H 

Synonyms: Ilyarachna longicornis G. O. Sars, 1864, 

p. 212; — 1897, p. 136, PI. LIX; — Hult, 1941, pp. 

97-100 and references. Ilyarachna hirticeps G. O. Sars; 

— Hult, 1941, p. 97 and references. 

Diagnosis: Ilyarachna with uniramous uropods. 

Cephalon and peraeon smooth, without dorsal spines. 

Mandibular palp triarticulate. First antenna with 

nine articles in female and 13 articles in male. Apex 

of pleon pointed. Frontal margin of cephalon almost 

straight, width of basal article of first antenna equal to 

one-seventh the width of cephalon. Pleon with one 

somite.

158 


Figure 46. Ilyarachna nodifronoides, n. sp. A: third pleopod; B: mandible female allotype; 

G: uropod female allotype; D: first antenna; E: first pleopod; F: dorsal view male holotype; 

G: second male pleopod. 

Measurements: Adult female length about 3 mm. 

(Sars, 1897). 

Type locality: Skager Rak, Norway (?). 

Distribution: Subarctic and Arctic seas, and North 

Atlantic, panarctic boreal, eurybathic (Hult, op. cit., 

p. 100). It was taken by the Ingolf from 14 stations 

(Hansen, 1916, p. 124) and by the Thor from four 

stations (Hansen, op. cit.). One Ingolf station was 

abyssal: Station 113, latitude 69° 31' N., longitude 

7°06'W., 2465 meters, temperature —1.0° C., one 

specimen. The species was not captured by the Vema. 

Ilyarachna derjugini Gurjanova 

Figure 45 I 

Synonyms: Ilyarachna derjugini Gurjanova, 1946a, 

pp. 275-276, 294, Fig. 6. 

Diagnosis: Ilyarachna with uropodal structure unknown. 

Cephalon and peraeon devoid of dorsal 

spines. Apexofpleon pointed. Coxal plates of second 

peraeonal somite strongly recurved and pointed. Pleon 

with one somite (otherwise as in hirticeps). (After 

Gurjanova, op. cit.) 

Measurements: Length 4 mm. 

Type locality: Arctic Ocean, Sedov Station 100, 

1938, latitude 81° 10' N., longitude 137° 17' E., 2500 

meters (Gurjanova, op. cit. p. 293). 


Affinities: Closely related to and possibly identical 

with /. longicornis G. O. Sars, as judged from Gurjanova's 

illustration and the statements by Hult, 1941, 

p. 97. 

Ilyarachna nodifronoides, new species 

Figure 46 


Diagnosis: Ilyarachna with two pleonal somites. 

Cephalon and peraeon without dorsal spines. Uropod


Figure 47. A: Ilyarachna africana, n. sp., dorsal view female holotype. B-C: Ilyarachna 

spinoafricana, n. sp. B: dorsal view male holotype; C: first male pleopod. D-I: Ilyarachna 

simplex, n. sp. D: first antenna; E: mandible; F: dorsal view female holotype; G: third 

pleopod; H: maxillipedal epipod; I: maxilliped. J-L: Ilyarachna multispinosa, n. sp. 

J: male first pleopod; K: dorsal view holotype male fragment; L: uropod. 

with single ramus, peduncle produced into a process 

extending beyond the length of the uropodal ramus. 

Width of basal article of first antenna about one-fifth 

the width of cephalon. Apex of pleon evenly rounded. 


width pleon 0.8 mm., allotype female length 7.0 mm., 



No. 52, types and 13 female, four male paratypes, 

cat. no. 1-52. 


Affinities: In general shape this species is similar to 

Eurycope nodifrons Hansen, from which it differs in 

lacking the incisions at the apex of the male first 

pleopods. The uropoda are Ilyarachna type, not 

Eurycope. 

Ilyarachna africana, new species 

Figure 47 A 


Diagnosis: Ilyarachna with one pleonal somite. 

Cephalon, peraeon, and pleon without spines dorsal


or lateral. Uropoda missing. Pleon shield-shaped, 

apex triangulate. First article of first antenna onethird 

to one-fourth the width of cephalon. Coxal plate 

of second somite not curved like a hook. 




No. 14, type and one female paratype, cat. no. 

1-159. 


Affinities: This species belongs to the smooth body 

group of Ilyarachna. Its wide triangulate basal article 

of the first antenna is distinctive. 

Ilyarachna spinoqfricana, new species 

Figure 47 B-C 



Cephalon, peraeon, and pleon without dorsal spines. 

First peraeonal somite laterally with a pair of stout 

spines. Epimera of second somite not curved and 

hook-like but bearing a stout seta. Pleon shield-like, 

apex triangulate. First article of first antenna onefifth 

the width of cephalon. Uropodal structure not 

known. 



pleon 0.7 mm. 




Affinities: Related to africana but having stout 

coxal plate spines lacking from africana. 

Ilyarachna simplex, new species 

Figure 47 D-I 


Diagnosis: Ilyarachna with pleon of two somites. 

Dorsum of cephalon, peraeon, and pleon without 

spines. Antero-lateral angles of pleon with a stout 

spine, apex of pleon narrowly rounded. Structure of 

uropod not known. Width of basal article of first 

antenna about one-fifth the width of cephalon. 

Cephalon with a spine on each lateral margin. Coxal 

plates of second peraeonal somite not curved and 

hook-like. 






Affinities: Related to africana and spinoqfricana 

but with stout seta at antero-lateral angle of 

pleon. 

Ilyarachna multispinosa, new species 

Figure 47 J-L 



Peraeon and pleon with dorsal spines. Each lateral 

border of pleon with five stout two-pointed setae, 

apex pointed, triangulate, and spinulate. Uropod 

with a single ramus only, extending beyond apex of 

peduncle. Seventh peraeonal somite with three to four 

spines at lateral border and only five on dorsum. 

Measurements: Holotype male fragment length 2.4 





Affinities: This species is related to /. argentinae and 

/. spinosissima, from which it differs in the arrangement 

of the spines on the pleon and peraeon. 

Ilyarachna argentinae, new species 

Figure 48 A-D 


Diagnosis: Ilyarachna with pleon of two somites. 

Peraeon and pleon with many stout two-pointed setae 

or spines on dorsum and at lateral borders. Each 

lateral border of pleon with five stout two-pointed 

setae, apex pointed, triangulate, and spinulate. 

Uropod with single ramus only extending beyond 

apex of peduncle. Seventh peraeonal somite with three 

spines at lateral border and eight on dorsum. 

Measurements: Intersex fragment length not known 





Affinities: This species is close to /. multispinosa, 

from which it differs in having more spines on pleon 

and at lateral borders of the peraeonal somites. 

Ilyarachna gurjanovae, new species 

Figure 48 E 



Cephalon, peraeon, and pleon with dorsal spines. 

Uropod with one branch. Each lateral border of 

pleon with seven stout setae. Dorsum of seventh 

peraeonal somite with six stout setae, lateral borders 

with two stout setae. Apex of pleon triangulate, 

smooth. 

Measurements: Female allotype length 3.2 mm., 




Distribution: Known only from type locality.

Figure 48. A-D: Ilyarachna argentinae, n. sp. 

A: intersex fragment; B: uropod; C: ventral 

view of pleon; D: first male pleopod. 

E: Ilyarachna gurjanovae, n. sp., dorsal view 

female allotype. 

Affinities: This species is related to I. argentinae 

and 7. multispinosa, from which it differs in the spines 

on the dorsum of the pleon and the last peraeonal 

somite. 

Ilyarachna indentifrons, new species 

Figure 49 A-C 



Cephalon, peraeon, and pleon devoid of dorsal spines. 

Uropod with a minute ramus which does not extend 

to end of peduncle. First article of first antenna onefourth 

the width of cephalon. Antero-lateral angles 

of pleon evenly rounded, apex evenly rounded. 



Type locality: South atlantic, L.G.O. Biotrawl No. 

53, type and 20 fragment paratypes. 



Affinities: This species is a smooth body form, 

distinguished from the others by its uniramous uropods, 

by the lack of spines at the antero-lateral border 

of the pleon, and by the very broad first article of the 

first antenna. 

Ilyarachna triangulata, new species 

Figure 49 D-E 



Cephalon, peraeon, and pleon without dorsal spines. 

Coxal plates at peraeonal somite 2 not recurved and 

hook-like.. Pleon shield-like with acute antero-lateral 

angles bearing several fine setae. Apex of pleon 

pointed. Basal article of first antenna about onefifteenth 

the width of cephalon. Uropods lost. 

Figure 49. A-C: Ilyarachna indentifrons, n. sp. 

A: dorsal view female holotype; B: first 

male pleopod; C: uropod. D-E: Ilyarachna 

triangulata, n. sp. D: mandible; E: dorsal 

view female holotype. F-G: Ilyarachna scotia, 

n. sp. F: dorsal view female holotype; G: 

uropod.

162 ROBERT J. MENZrES 




No. 14, type and one fragment, cat. no. 1-160. 


Affinities: This species is somewhat similar to 

africana, but has more acute antero-lateral angles to 

the pleon and proportionally much narrower basal 

articles to the first antenna; in these respects it also 

differs from simplex. The mandible shows reduction 

of structure. 

llyarachna scotia, new species 

Figure 49 F-G 


Diagnosis: llyarachna with one pleonal somite. 

Uropoda biramous, exopod one-third the length of 

endopod and both much shorter than the peduncle. 

Cephalon, peraeon, and pleon devoid of dorsal 

Diagnosis: Paraselloidea with cephalon free. All 

peraeopods except the first modified for swimming, 

not paddle-like, provided with plumose marginal 

setae. Mandibles with toothed incisor, lacinia, and 

setal row, palp triarticulate or lacking, molar reduced 

to setiferous lobe. First four peraeonal somites with 

large coxal plates visible in dorsal view. Last three 

peraeonal somites without coxal plates visible in dorsal 

view. Pleon with one or two somites. Uropoda 

unibiramous, with quadrate, ventral peduncle. Flagellum 

of first antenna pauciarticulate, without specialized 

vesicle or bladder. Frontal region of cephalon 

well developed. 

Composition: The family contains only two genera, 

Echinopleura G. O. Sars and Desmosoma G. O. Sars. 

Only Desmosoma contains abyssal species. In Echinopleura 

the fifth peraeonal somite is constricted and 

longer than wide, whereas it is not constricted in 

Desmosoma. 

Genus: DESMOSOMA G. O. Sars 

Type species: Desmosoma lineare G. O. Sars, 1864, 

p. 215; — 1899, pp. 125-126. 

Synonyms: Desmosoma Sars, 1863; — Meinert, 

1890; —Bonnier, 1896; —Sars, 1899; — Stephensen, 

1915; — Hansen, 1916; — Monod, 1926b; — 

Nordenstam, 1933; — Hult, 1941. Eugerda Meinert, 

1890; — Vanhoffen, 1914; —Hult, 1941. 

Diagnosis: Desmosomidae with fifth peraeonal 

somite not constricted and elongated. 

Composition: This genus now contains around 25 

species and is well represented in polar, shallow water, 

Family: DESMOSOMIDAE 

spines or setae. Coxal plates of second peraeonal somite 

not hook-like and recurved. Pleon shield-shaped 

without sharp angles, apex rounded. Basal article of 

first antenna about one-fifth the width of cephalon. 






Affinities: Related to /. indentifrons but differing in 

having biramous instead of uniramous uropods. 

llyarachna species indeterminable 

Fragments of llyarachna were taken at L.G.O. 

Biotrawl no. 14, one female fragment; no. 54, 

two fragments; no. 98, one cephalon; no. 107, one 

crushed; no. 201, four damaged; no. 212, four 

fragments; no. 218, three fragments; no. 231, five 

fragments. 

and deep sea regions. The known species are shown 

in the accompanying list. All species except D. 

elongatum Bonnier (illustration not available) and a 

proposed new one are included in the key. It has been 

assumed that the uropoda of D'. falklandicum Nordenstam 

were biramous. This assumption may have been 

incorrect, in which case its position in the key would 

have to be changed. 

LIST OF SPECIES OF DESMOSOMA 

Species 

1. tenuimanum G. O. Sars 

2. latipes Hansen 

3. lineare G. O. Sars 

4. elongatum Bonnier 

5. longispinum Hansen 

6. simile Hansen 

7. gracilipes Hansen 

8. politum Hansen 

9. coarctatum (Hansen) G.O.S. 

10. laterale (Hansen) 

11. armatum G. O. Sars 

12. angustum Hansen, G.O.S. 

13. chelatum Stephensen 

14. insigne Hansen 

15. plebejum Hansen 

16. australis Nordenstam 

17. brevipes Nordenstam 

18. modestum Nordenstam 

19. falklandicum Nordenstam 

20. polaris Gurjanova 

21. zenkewitschi Gurjanova 

22. reticulata Gurjanova 

23. longimanum (Vanhoffen) 

24. filipes Hult 

25. intermedium Hult 


Least 

11 

1094 

50 

950 

3521 

2258 

2258 

1070 

24 

50 

25 

50 

25 

2702 

1412 

64 

64 

125 

16 

40 

65 

698 

2735 

34 

30 

Greatest 

698 

1094 

697 

950 

3521 

2258 

2702 

1505 

2702 

1096 

478 

680 

25 

2702 

1666 

148 

148 

250 

16 

510 

65 

698 

2735 

1000 

2258


DESMOSOMA 

1. Uropoda biramous 2 

1. Uropoda uniramous 11 

2. Pleon with postero-lateral spines 3 

2. Pleon without postero-lateral spines, rounded . . 8 

3. First peraeopod stout, with long stout setae . . . 4 

3. First peraeopod weak, without long 

stout setae Jilipes Hult 

4. Fifth peraeonal somite with a stout seta at 

antero-lateral angles coarctatum (Hansen) 

4. Fifth peraeonal somite without a stout seta at 

antero-lateral angles 5 

5. Antero-lateral angles of fifth peraeonal 

somite sharp reticulata Gurjanova 

5. Antero-lateral angles of fifth peraeonal somite 

rounded 6 

6. First peraeopod with only one long stout setae on 

carpus longimana (Vanhoffen) 

6. First peraeopod with two or more stout setae on 

carpus 7 

7. With two stout setae laterale (Hansen) 

7. With five stout setae politum Hansen 

8. First peraeopod stout with four stout 

setae zenkewitschi Gurjanova 

8. First peraeopod weak, with no setae or five 

stout setae 9 

9. Lateral border of pleon 

serrated intermedium Hult 

9. Lateral border of pleon not serrated 10 

10. Coxal plate of second peraeonal somite 

triangulate tenuimanum G. O. Sars 

10. Coxal plate of second peraeonal somite 

rounded latipes Hansen 

11. Pleon with spine or tooth at postero-lateral 

angle 12 

11. Pleon rounded at postero-lateral margin, no tooth 

present 17 

12. First peraeopod stout, with stout setae 13 

12. First peraeopod weak, without stout setae . . . 14 

13. First antenna with six articles . . . . birsteini, n. sp. 

13. First antenna with five articles . armatum G. O. Sars 

14. Coxal plates elongate, much longer than wide . . 15 

14. Coxal plates short, about as wide as long . . . . 16 

15. Lateral borders 6-7 peraeonal somites 

subcircular magnispinum, n. sp. 

15. Lateral borders 6-7 peraeonal somites 

almost straight longispinum Hansen 

16. Antero-lateral angles of fifth peraeonal somite 

sharply pointed simile Hansen 

16. Antero-lateral angles of fifth peraeonal 

somite rounded gracilipes Hansen 

17. First peraeopod stout, with stout setae 18 

17. First peraeopod weak, without stout setae . . . 22 

18. Fourth peraeonal somite with pronounced spine at 

antero-lateral angle insigne Hansen 

18. Fourth peraeonal somite without spine at anterolateral 

angle 19 

19. Fifth peraeonal somite not longer than wide . . 21 

19. Fifth peraeonal somite longer than wide . . . . 20 

20. Frons of cephalon straight plebejum Hansen 

20. Frons of cephalon convex . . . . angustum Hansen 3, 


5-6 rounded chelalum Stephensen 


5-6 sharp polaris Gurjanova 

22. Fifth peraeonal somite longer than wide . . . . 25 

22. Fifth peraeonal somite not longer than wide . . . 23 


23. Coxal plates elongated and pointed, produced 

forward at apex lineare G. O. Sars 

23. Coxal plates rectangular, or not elongate and 

pointed 24 

24. First peraeonal somite much shorter than 

second brevipes Nordenstam 

24. First peraeonal somite as long as 

second falklandicum Nordenstam 

25. First peraeonal somite one-half as long as 

second modeslum Nordenstam 

25. First peraeonal somite one-third as long as 

second australis Nordenstam 

a Ref. G. O. Sars, 1899, suppl. PI. II, fig. 2. 

Desmosoma gracilipes Hansen 

Figure 50 A-B 

Synonyms: Desmosoma gracilipes Hansen, 1916, pp. 

113-114, PI. 11. 

Diagnosis: Desmosoma with a spine at each postero 

lateral angle of the pleon. Frons of cephalon trans 

verse at apex. Goxal plates bilobed and quadrate. 

First peraeonal somite and second subequal in length. 

First peraeopod weak, without stout setae. Uropoda 

uniramous. 

Measurements: Female with marsupium length 

3.2 mm., male 2.7 mm. 



2258 meters, temperature 2.4° C, five specimens (one 

male). 

Distribution: Also from Ingolf Station 36, Davis 


meters, temperature 1.5° C, one specimen (Hansen, 

op. cit.). 

Affinities: This species is close to D. simile Hansen, 

but has the antero-lateral angle of the fifth peraeonal 

somite rounded, not sharply pointed. 

Desmosoma insigne Hansen 

Figure 50 C-E 

Synonyms: Desmosoma insigne Hansen, 1916, pp. 

118-120, PI. 11. 

Diagnosis: Desmosoma without a spine at each 

postero-lateral angle of pleon. Frons of cephalon 

blunt at apex. Coxal plates bilobed and quadrate. 

First peraeonal somite longer than second. Fourth 

peraeonal somite as long as wide, with acute antero 

lateral angles. First peraeopod stout and with a 

stout seta on merus. Uropoda uniramous. 

Measurements: Female with marsupium length 3.1 

mm., male 1.85 mm. (Hansen, op. cit.). 



2702 meters, temperature 1.5° C, six specimens 



Affinities: The spines at the antero-lateral margins 

of the peraeonal somites are distinctive.


Figure 50. A-B: Desmosoma gracilipes Hansen. A: dorsal view ovigerous female; B: uropods 

of subadult female. C-E: Desmosoma insigne Hansen. C: dorsal view of female with marsupium; 

D: uropods and abdomen of female. E: first peraeopod. F-G: Desmosoma simile 

Hansen. F: uropods and abdomen of female; G: dorsal view of ovigerous female. H-J: 

Desmosoma intermedium Hult. H: first male pleopod; I: uropod; J: male pleotelson. 

K: Desmosoma coarctatum (G. O. Sars), after Hansen, natator, dorsal view male. L-M: Desmosoma 

longispinum Hansen. L: dorsal view of male; M: abdomen and uropods of male. 

Desmosoma simile Hansen 

Figure 50 F-G 

Synonyms: Desmosoma simile Hansen, 1916, pp. 112- 

113. 

Diagnosis: Desmosoma with a long spine at each 

postero-lateral angle of the pleon. Frons of cephalon 

transverse at apex. Coxal plates slightly elongate, 

bilobed. First and second peraeonal somites subequal 

in length; fifth with projecting spine-like anterolateral 

angles. First peraeopod weak, without stout 

setae. Uropods uniramous. 

Measurements: Ovigerous female length 2.2 mm. 




2258 meters, temperature 2.4° C, five specimens 

(Hansen, op. cit.).


Affinities: Close to gracilipes but with the anterolateral 

angle of the fifth peraeonal somite pointed 

rather than rounded. 

Desmosoma intermedium Hult 

Figure 50 H-J 

Synonyms: Desmosoma intermedium Hult, 1936, pp. 

2-6, Figs. 1-21; — 1941, pp. 80-84. 

Diagnosis: Desmosoma without a spine at each 

postero-lateral angle of the pleon but with lateral 

margins serrated. Frons of cephalon concave at apex. 

Coxal plates triangular and minute, not strongly 

produced. First peraeonal somite slightly shorter 

than second. First peraeopod weak without stout 

setae. Uropoda biramous. 


Type locality: Koster Fjord, off Vattenholm, 206 

meters, temperature 6.2° C. (Hult, 1936). 

Distribution: North Atlantic, Norway, Kattegat, 

100 meters to 2258 meters, and Ingolf Station 24, 


Affinities: Looking much like D. elongatum Bonnier 

but with uniramous uropods. 

Desmosoma coarctatum (Hansen) G. O. S. 

Figure 50 K 

Synonyms: Eugerda coarctata G. O. Sars, 1899, p. 

253, Desmosoma natator Hansen, 1916, p. 115; — 

Gurjanova 1933, p. 418. Desmosoma coarctatum (G. O. 

Sars), Hult 1936, p. 10; — 1941, pp. 86-88 and 

references. 

Diagnosis: Desmosoma with a spine at each posterolateral 

angle of pleon. Frons of cephalon straight at 

apex. Coxal plates slightly produced, bilobed. First 

and second peraeonal somites subequal in length. 

Fifth with a long spine at each antero-lateral angle. 

First peraeopod stout, with stout seta. Uiopoda 

uniramous. 

Measurements: Female length 2.0 mm., male 1.5 

mm. (G. O. Sars, op. cit., p. 253). 

Type locality: North Atlantic, Skager Rak, north 

of Skagen, 125 fathoms (G. O. Sars, op. cit., p. 250). 

Distribution: Besides the Skager Rak (Hult, 1941) 

the species was found at Davis Strait, Ingolf Station 

36, latitude 61° 50' N., longitude 56° 21'W., 2702 

meters, temperature 1.5° C, one specimen (Hansen, 

op. cit., p. 116). 

Affinities: This species is unique in having the 

stout spines at the antero-lateral angles of the fifth 

peraeonal somite. 

Desmosoma longispinum Hansen 

Figure 50 L-M 

Synonyms: Desmosoma longispinum Hansen, 1916, pp. 

111-112, PL 10. 


Diagnosis: Desmosoma with a long spine at each 

postero-lateral angle of the pleon. Frons of cephalon 

rounded slightly at apex. Coxal plates elongated, 

strongly produced forward, over twice as long as wide, 

and pointed at apex. First and second peraeonal 

somites subequal in length. First peraeopods weak; 

without stout setae. Uropods uniramous. 

Measurements: Female length 2.1 mm., male 1.8 

mm. (Hansen, op. cit.). 


Strait, Ingolf Station 38, latitude 59° 12' N., 

longitude 51° 05' W., 3521 meters, 4 specimens 

(Hansen, op cit.). 


Affinities: This species is close to magnispinum but 

has the lateral borders of the peraeonal somites 

6-7 straight rather than rounded. 

Desmosoma striata, new species 

Figure 51 A-F 

Synonyms: Non e. 

Diagnosis: Desmosoma without spines at each postero-lateral 

border of pleon. Pleon evenly rounded, 

lacking serrations. Coxal plates bilobed. First and 

second peraeonal somites subequal in length. First 

with stout spines at antero-lateral angle. Fifth 

without spines at antero-lateral angles. Structure of 

first peraeopod not known. Uropods uniramous. 

Measurements: Female with oostegites length 1.4 





Affinities: Because of the absence of the first peraeopods 

it is difficult to determine the affinities of this 

species. The stout spines at the first peraeonal somite 

are distinctive. 

Desmosoma magnispinum, new species 

Figure 51 G-J 


Diagnosis: Desmosoma with a pronounced long 

spine at postero-lateral angle of pleon. Coxal plates 

much elongated, pointed. First and second peraeonal 

somites subequal in length. Fifth without spines at 

antero-lateral angles. Lateral borders of sixth and 

seventh semicircular. First peraeopod weak, without 

stout setae. Uropods uniramous. 



Type locality: North Atlantic, Bay of Panama, 

L.G.O. Biotrawl No. 103, type only, cat. no. 1-176. 


Affinities: This species is similar to D. longispinum 

Hansen, from which it differs in having semicircular 

lateral borders to peraeonal somites 6-7.


Figure 51. A-F: Desmosoma striata, n. sp. A: dorsal view female with oostegites; B: first 

antenna; C: maxilliped; D: uropod; E: third peraeopod; F: mandible. G-J: Desmosoma 

magnispinum, n. sp. G: dorsal view male holotype; H: pleopod ventral view; I: uropod; 

J: first antenna. K-M: Desmosoma birsteini, n. sp. K: dorsal view gravid female holotype; 

L: first antenna; M: uropod. 

Desmosoma birsteini, new species 

Figure 51 K-M 


Diagnosis: Desmosoma with a stout spine at each 

postero-lateral angle. Coxal plates triangulate and 

bilobed. First peraeonal somite slightly shorter than 

second. Fifth without spines at antero-lateral angles. 

First peraeopod stout with long stout seta. Uropods 

uniramous. 

Measurements: Gravid female holotype length 2.3 


Type locality : North Atlantic, L. G. O. Biotrawl No. 

9, holotype only, cat. no. 1-170. 


Affinities: This species is close to D. armatum G. O. 

Sars, from which it differs in having six articles to the 

first antenna instead of five. The pleonal spines are 

also more pronounced on birsteini. 

Desmosoma species indeterminable 

Fragments of Desmosoma were found at: L.G.O. 

Biotrawl No. 16, one female; No. 18, one multilated; 

No. 49, one fragment; No. 231, one fragment.

Synonyms: Dendrotioniidae Vanhoffen, 1914; — 

Dendrotiini Nordenstam, 1933, pp. 198-199. 

Diagnosis: Paraselloidea with free cephalon. All 

peraeopods ambulatory. Mandibular incisor with 

teeth, lacinia with teeth, molar expanded, truncated. 

Maxillipedal palp with narrow subsimilar articles, all 

less than one-half the width of endite. Uropods with 

long peduncle, biramous. 

Composition: This family contains Dendrotion G. O. 

Sars, a shallow water genus, and the new abyssal genus 

described herein. I have transferred Mormomunna 

Vanhoffen and Pseudomunna Hansen to the Munnidae 

(p. 172-173.) 

A KEY TO THE GENERA OF THE 

DENDROTIONIIDAE 

1. Mandible with palp 

1. Mandible without palp 

DENDROMUNNA, new genus 


Family: DENDROTIONIIDAE 

Dendrotion G. O. Sars 

Dendromunna, n. gen. 

Type species: Dendromunna spinipes, new species. 

Diagnosis: Dendrotioniidae with one pleonal somite. 

Mandible lacking palp. Coxal plates visible 

in dorsal view on peraeonal somites 2-6 inclusive. 

Lateral borders of peraeonal somites expanded into 

spine-like processes, each process with an apical 

cluster of spines. Dorsum of body with similar projections. 

Uropoda biramous, rami shorter than 

peduncle. 

Composition: This genus contains only the type. 

Dendromunna spinipes, new species 

Figure 52 A-B 


Diagnosis: Dendromunna with a pair of stout 

apically spinous spine-like processes on dorsum of 

peraeonal somites 2-4 inclusive. Uropoda with rami 

one-sixth the length of the stout peduncle. Eyes 

Diagnosis: Paraselloidea with free head, eyes 

lacking, mandibles normal, molar process well 

developed, expanded at truncated apex. Antennae 

shorter than body. First antenna much shorter than 

second antenna. All peraeopods simple, last six 

walking legs. Dactyls of last six peraeopods with two 

claws. Pleon with one somite only. Uropoda uniramous 

or biramous, peduncle present. Maxillipedal 

palp with first three articles expanded, as wide as 

Family: IANIRELLIDAE 

Figure 52. A-B: Dendromunna spinipes, n. sp. 

A: dorsal view female holotype; B: maxilliped. 

C: lanirella lobata Richardson, dorsal 

view intersex. 

lacking. Frons of cephalon concave. Apex of pleon 

convex and fringed with setae. 






Affinities: Unique. 

endite. Anus contained in branchial chambers. 

(Modified from Menzies, 1956a, p. 11.) 

Composition: This family contains at least two 

related genera, lanirella and Spinianirella, and possibly 

Rhacura. The species lanirella pusilla type of lanirella 

Sayce, being a homonym, deserved a new name, which 

Richardson (1904, p. 6) suggested as Heterias. It does 

not belong to lanirella Bonnier.


Genus: IANIRELLA Bonnier, 1896 Ion with a pair of spines. Each peraeonal somh- 

and pleon with a pair of dorsal spines. Three later; 

Synonym: lanirella Bonnier, 1896, p. 587; not projections on each side of pleon; each is rounded, r.. - 

lanirella Sayce, 1900, p. 124. pointed. Cephalon with rostrum, but spines a: 

Type species: lanirella nanseni Bonnier, 1896, p. 587, lacking from it 

pi on ^ 

Measurements: None given. 

Diagnosis: Same as for the family; coxal plates Type locality: North Atlantic, southeast of George 

visible in dorsal view on peraeonal somites 5-7 Bank, ^ ^ < m Station 2571, 2480 meters, three spec - 

inclusive. Uropoda with peduncle umramous. menS; cat nQ 3 8 % 7 j TJ. S. N - M. 

Composition: The genus contains eight species, all Distribution: Southeast of Georges Bank, Albatr, 

from the Atlantic Ocean. Three are known from station 2572, 3225 meters, and ,1/iafro* Station 257i 

abyssal depths, the remainder from bathyal depths. Qiaf; meters 

Two additional new abyssal species are described here. AffinUm . ' This spedes h unique m haying rQunde. 

LIST OF THE SPECIES OF IANIRELLA 

lateral borders of the somites. 


Species Least Greatest lanirella bifida, new species 

1. nanseni Bonnier 950 950 

2. lobata Richardson 2480 3225 

3. spongicola Hansen 913 913 Synonyms: None. 

4. laevis Hansen 2258 2702 Diagnosis: lanirella with lateral borders of peraec - 

5. glabra Richardson 946 946 nal extensions sharply pointed. Dorsum of cephalo; 

6. vemaeMenzies 5104 5122 peraeon, and pleon without spines. Lateral border 

7. abyssicola Richardson 

8 A St h 

1205 

1227 

1205 

1227 

c , , ., , ,. . , 

pleon each with three stout apically spined pre- 

9. caribbica Menzies 1169 1169 jections. Apex of pleon bluntly pointed. Cephalo: 

A KEY TO THE SPECIES OF IANIRELLA 

lacks rostrum, but frons has a medial pair of spine: 

projections. 

1. Lateral processes on peraeonites Measurements: Holotype, intersex, length 3.8 mm 

rounded lobata Richardson width pleon 1.2 mm. 

1. Lateral processes on peraeonites pointed . . . . 2 Typg locdity. South Atlantic, L.G.O. Biotrav, 

2. Body with dorsal spines 

o D J .u . A i 

8 

i 

..T _„ ^ ^ T . or> 

No. 53, type, cat. no. 1-183. 

1. Body without dorsal spines 3 > /*- > 

3. Lateral borders of pleon each with five major Distribution: Known only from type locality, 

projections abyssicola Richardson Affinities: Related to vemae but with a bifid fron: 

3. Lateral borders of pleon each with three projec- on the cephalon. 

tions 4 

4. Rostrum lacking 5 

4. Rostrum present 6 lanirella laevis Hansen 

5. Frons of cephalon rounded 

5. Frons of cephalon bifid 

vemae Menzies 

bifida, n. sp. 

-p- rf. ZQ p_p 

6. Rostrum with apical spines 7 

6. Rostrum without apical spines . . magnifrons, n. sp. Synonyms: lanirella laevis Hansen, 1916, p. 26, PI. I 

7. Rostrum with four apical spines . . . . laevis Hansen Diagnosis: Ianirella with lateral borders of peraec- 

7. Rostrum with three spines . . . . glabra Richardson rial extensions sharply pointed. Dorsum of cephaloi: 

8. Submedian spines of 3-4 

shorter than medial spine 

peraeonal somite 

9 

peraeon, and pleon smooth. 

. . , ,. 

Lateral borders of pleo: 

. , . . 

8. Submedian spines of 3^ peraeonal somite 

each WIth two stout a P lcalI y s P ined Projections, ape- 

longer than medial spine nanseni Bonnier of pleon pointed. Cephalon with rostrum bearing 

9. Medial spine at front of cephalon as wide four stout spines. 

as long spongicola Hansen Measurements: Largest female length 4.0 mm 

9. Medial spine at front of cephalon much longer fVt*r,*t*n r>n r!t \ 

^nauscii, op. cii.j. 

10. Pleonîth dorsal spines '.'.'.'.'. 'caribbica Menzies ^ localit y : North Atlantic > /^/Station 24 

10. Pleon without dorsal spines . . . bonnieri Stephensen latitude 63° 06'N., longitude 56° 00'W., 2258 meters 

temperature 2.4° C, seven specimens. 

lanirella lobata Richardson Distribution: Also known from Ingolf Station no 

Figure 52 C 

36 > latitude 61° 50' N., longitude 56° 21' W., 270meters, 

temperature 1.5° C., four specimens (Hansen 

Synonyms: lanirella lobata Richardson, 1908, pp. op. cit.). 

78-79, Figs. 8-11. Affinities: This species is allied to/, glabra Richard - 

Diagnosis: lanirella with lateral borders of peraeo- son, from which it differs in having four spines, no: 

nal extensions blunt and rounded. Dorsum of cepha- three, on the apex of the cephalic rostrum.


Figure 53. A-D: lanirella bifida, n. sp. A: dorsal view holotype intersex; B: maxilliped; 

C: firstantenna; D: first peraeopod. E-G: lanirella laevis Hansen. E: dorsal view female; 

F: ventral view abdomen; G: anterior of cephalon. 

lanirella vemae Menzies 

Figure 54 A-B 

Synonyms: lanirella vemae Menzies, 1956a, p. 12, 

Fig. 5. 

Diagnosis: lanirella with lateral borders of peraeonal 

extensions sharply pointed. Dorsum of cephalon 

peraeon and pleon without spines. Lateral borders of 

pleon each with three stout apically spined projections. 

Apex of pleon blunt, setiferous. Cephalon lacks rostrum. 

Measurements: Holotype, intersex, length 3.3 

mm., width at second peraeonal somite 1.8 mm. 

(Menzies, op. cit.). 

Type locality: North Atlantic, near Puerto Rico 

trench, L.G.O. Biotrawl No. 1, 5104-5122 meters, 

type only, cat. no. 11761, A.M.N.H. 


Affinities: This species is related to bifida, from 

which it differs in having the frons of the cephalon 

rounded and not bifid. 

lanirella magnifrons, new species 

Figure 54 C-D 


Diagnosis: lanirella with lateral borders of peraeonal 

projections pointed. Dorsum of cephalon, peraeon


Figure 54. A-B: Ianirella vemae Menzies. A: dorsal view holotype intersex; B: uropod. 

C-D: Ianirella magnifrons, n. sp. C: dorsal view female intersex; D: first antenna. 

and pleon without spines. Lateral borders of pleon 

each with three stout apically spined projections. 

Apex of pleon blunt. Cephalon with spatulateshaped 

rostium. Lateral margins of body and pleon 

spinulate. 

Measurements: Female intersex length 3.2 mm., 





Affinities: The absence of apical spines on the 

rostrum distinguishes this species from laevis and 

glabra. 

SPINIANIRELLA, new genus 


Type species: Spinianirella walfishensis, new species 

Diagnosis: Ianirellidae with coxal plates visible in 

dorsal view on peraeonal somites 3-7 inclusive. 

Spinous expansions at lateral border of cephalon and 

peraeonal somites 1-6 inclusive. Mandibular palp 

triarticulate. Second from last article of prehensile 

first peraeopod longer by one-half than the propoda"; 

article and with many stout spines and setae alone 

inferior margin. Pleon with serrated lateral margins, 

spiniform extensions lacking.


Figure 55. Spinianirella walfishensis, n. sp. A: dorsal view female holotype; B: right mandible; 

C: left mandible of paratype; D: first peraeopod; E: maxilliped; F: maxillipedal epipod. 

Spinianirella walfishensis, new species 

Figure 55 


Diagnosis: Spinianirella with 13 spines on either 

side of pleon, apex rounded and smooth. Frons of 

cephalon evenly convex. Dorsum of body and pleon 

without spines. First antenna with six articles. Maxilliped 

without coupling hooks. 



Type locality: South Atlantic Ocean, L.G.O. 

Biotrawl No. 16, holotype and one paratype, cat. no. 

1-192. 

Distribution: Found also at L.G.O. Biotrawl No. 

54, one female, cat. no. 1-199. 


Genus: RHACURA Richardson 

Synonyms: Rhacura Richardson 1908a, pp. 72-74. 

Type species: Rhacura pulchra Richardson. 

Diagnosis: Ianirellidae (?) with eyes, without 

coxal plates visible in dorsal view. Cephalon incised 

laterally. Pleon laterally with several deep incisions. 

Last two articles of maxillipedal palp narrow; others 

as wide as endite. Structure of mandibles not known.


Rhacura pulchra Richardson 

Figure 56 F 

Synonyms: Rhacura pulchra Richardson, 1908a, pp. 

74-75. 

Description: "Body oblong-ovate, about twice as 

long as wide. Dorsal surface covered with granulations. 

Head much wider than long, with the front 

Figure 56. A-B: Munna (Munna) acanthi/era 

Hansen. A: dorsal view head; B: dorsal 

view posterior. C-E: Munna (Munna) argentinae, 

n. sp. C: dorsal view female holotype; 

D: first peraeopod; E: uropod. F: Rhacura 

pulchra Richardson, dorsal view female (from 

Richardson, 1906). 

produced in the middle in an obtuse triangular process, 

which does not extend as far as the antero-lateral 

processes; the lateral margins are drawn out on 

either side in two acute triangular processes, both 

Synonyms: Munnidae G. O. Sars, 1899; — Vanhoffen, 

1914. MunniniHansen, 1916; —Nordenstam, 

1933, pp. 197-198. 

Diagnosis: Paraselloidea with cephalon free from 

peraeon. All peraeopods ambulatory. Mandibles 

with expanded, truncated molar process. Maxilli- 

Family: MUNNIDAE 

directed anteriorly; the posterior one is slightly narrower 

than the anterior process. The eyes are minute 

and are situated closer to the posterior margin than to 

the anterior margin. The first pair of antennae have 

the first article of the peduncle largest; the second and 

third are subequal and are a little shorter than the 

first; the flagellum is composed of eighteen articles. 

The second pair of antennae are broken at the fourth 

article of the peduncle in the only specimen; the 

third article is furnished with an antennal scale. The 

maxillipeds have the first three articles of the palp 

expanded and dilated. The first segment of the 

thorax has the lateral margins drawn out on either 

side in one triangular expansion, acute at the extremity 

and directly anteriorly; the second and third 

segments have the lateral margins drawn out on either 

side in two triangular expensions [sic], about equal in 

width, one anterior and the other posterior; the 

fourth segment has one triangular expansion to the 

lateral margin on either side; the fifth and sixth segments 

have the lateral margins drawn out on either 

side in two triangular expansions of about equal size: 

the seventh and last segment of the thorax has the 

lateral margins drawn out in three triangular processes 

on either side, all of equal size. 

"The abdomen has the lateral margins drawn out 

on either side in four triangular expansions, the last 

expansion corresponding to the post-lateral expansion 

in the species of the genus Iolella; between the postlateral 

expansions is a small rounded lobe. The 

uropoda are lost in the only specimen. 

"The first pair of legs are prehensile, the other six 

ambulatory in character and furnished with biunguiculate 

dactyli. The margins of the entire body 

are armed with minute acute spinules. 

"The only specimen, a female, was found at 

Station 2572, steamer Albatross, southeast of Georges 

Bank, at a depth of 1,769 fathoms. 

"The type is in the U.S. National Museum, Cat. 

no. 38964." (Richardson, 1908a, pp. 74-75.) 

Measurements: None given. 

Type locality: North Atlantic, southeast of Georges 

Bank, Albatross Station 2572, 3225 meters, type only, 

cat. no. 38964 U.S.N.M. 


Affinities: Unique. Not collected by Vema. 

pedal palp with first three articles as broad as endite. 

Pleon with two somites 

Composition: According to Nordenstam, 1933, p. 

198, this family (or subgroup, as he called it) contained 

the following genera: Munna Kroyer, 1839: 

Paramunna G. O. Sars, 1866; Coulmania Hodgson.

1910; Notoxenus Hodgson, 1910; Austrosignum Hodgson, 

1910; and Echinomunna Vanhoffen, 1914. He was 

uncertain of the status of Austrurus Beddard, 1885. 

These genera, except for Munna (one species only), 

contain only shallow water species. It is probable that 

the genus Acanthomunna Beddard, 1885, also belongs 

to this family. Here one additional new species is 

described in Acanthomunna and a new genus is 

described. 

A KEY TO THE GENERA OF THE MUNNIDAE 

(Modified after Menzies, in press) 

1. Coxal plates of peraeon not visible in dorsal view . . 2 

1. Coxal plates of peraeon visible in dorsal view . . 3 

2. Mandible with triarticulate palp 4 

2. Mandible lacks palp Coulmania 

3. Coxal plates visible in dorsal view on peraeonal 

somites 2-7 inclusive 5 

3. Coxal plates visible in dorsal view only on peraeonal 

somites 5-7 inclusive 6 

4. Each somite of peraeon with single spine 

pn dorsal surface Notoxenus 

4. Peraeonal somites lack spines Paramunna 

5. Body strongly spinous 7 

5. Body lacks spines (may have stout setae) . . . Munna 

6. Ocular peduncles short, with ocelli . . . Austrosignum 

6. Ocular peduncles narrow, long, directed 

out from head as spine-like projections, 

ocelli lacking Notoxenoides, n. genus 

7. Uropoda insert dorsally, with stout peduncle 

and stout rami Acanthomunna 

7. Uropoda insert laterally, with rami small 

and leaf-like Echinomunna 

Genus: MUNNA Kreyer 

Synonyms: Haliacris Pfeffer, 1889. Caecimunna Richardson, 

1908a, p. 79. 

Type species: Munna boecki Kroyer, 1839. 

Diagnosis: Munnidae with coxal plates visible in 

dorsal view on peraeonal somites 2-7 inclusive. Body 

lacking spines. Eyes on short immovable peduncle, 

preocular lobes generally present. Uropoda lacking 

peduncle. 

Subgenus: MUNNA 

Reference: Menzies, in press. 

Type species: Munna boecki Krayer, 1839. 

Diagnosis: Munna with inferior uropodal ramus 

rounded in cross-section, lacking recurved apical 


Composition: This subgenus contains 14 species 

(Menzies, op. cit.). Only one species, Munna (M) 

acanthi/era Hansen, 1916, is known mainly from below 

shelf depth (viz., below 200 meters). The subgenus 

was represented in L.G.O. collections by a single 

blind abyssal species from the South Atlantic. 

Munna (Munna) acanthifera Hansen 

Figure 56 A-B 

Synonyms: Munna acanthifera Hansen, 1916, pp. 

40-42, PI. III. 


Diagnosis: Munna (sensu stricto) without eyes, 

cephalon with a triangulate lateral expansion, frons 

with five stout marginal spines. Epimeral areas 

strongly spinous. Pleon and peraeon with some stout 


Measurements: Length female 3.1 mm., male 2.8 

mm. 

Type locality: North Atlantic, from the following 

stations by the IngoIf and the Thor: 

Davis Strait: Ingolf Station 32, latitude 66° 35' N., 

longitude 56° 38' W., 599 meters, temperature 3.9° C, 

16 specimens; Ingolf Station 35, latitude 65° 16' N., 

longitude 55° 05' W., 682 meters, temperature 3.6° C, 

numerous specimens; Ingolf Station 27, latitude 


3.8° C, two specimens; Ingolf Station 25, latitude 


3.3° C, ten specimens; Ingolf Station 24, 


temperature 2.4° G, about 28 specimens. 

West of Iceland: Ingolf Station 89, latitude 64° 45' 


8.4° C, one specimen. 

Southwest of Iceland: Ingolf Station 81, latitude 


6.1° C, one specimen; Ingolf Station 78, 


temperature 4.5° C, seven specimens. 

East of Iceland: Ingolf Station 105, latitude 65° 34' 


—0.8° C, two specimens. 

North of Iceland: 7«£o//"Station 126, latitude 67° 19' 


—0.5° C. eight specimens; Ingolf Station 124, latitude 


—0.6° G, one specimen. 

South of Iceland, Thor, latitude 62° 11' N., longitude 

19° 36' W., 1899 to 2144 meters, temperature 

not recorded, three specimens (Hansen, 1916, pp. 

41-42). 

Affinities: The lateral cephalic spines are unique 

to this and to Caecimunna truncata Richardson, known 

from 80-390 fathoms off New England. 

Munna (Munna) argentinae, new species 

Figure 56 C-E 


Diagnosis: Munna (Munna) without eyes. First 

antenna with seven articles, last article one-half the 

length of prior article. Second antenna slightly longer 

than the body, flagellum with 20 articles. Cephalon as 

wide as long, preocular lobes absent, frontal margin 

convex, entire, without setae or spines. Maxilliped 

with three coupling hooks. Pleotelson pyriform, lateral 

margins smooth, lacking large setae or spines, a few 

minute setae along lateral margin. Uropoda inferior


ramus small, superior ramus lacking. Mandibular 

palp missing. 




No. 201, holotype only, cat. no. 1-217. 

Distribution: Known only from type locality.- 

Affinities: This is the first blind abyssal species of 

Munna known from the South Atlantic. It differs 

from M. (M.) acanthifera Hansen in lacking tri 

angulate expansions at the lateral margin of the 

cephalon. 

Genus: ACANTHOMUNNA Beddard 

Synonyms: Acanthomunna Beddard, 1886, pp. 102- 

103; — Mormomunna Vanhoffen, 1914, pp. 569-57. 

Pseudomunna Hansen, 1916, pp. 47-48. 

Type species: Acanthomunna proteus Beddard, 18&" 

pp. 47-50. 

Figure 57. Acanthomunna beddardi, n. sp. A: dorsal view male holotype; B: gnathopod; 

G: first antenna; D: second pleopod; E: first pleopod; F: mandible; G: maxilHped; 

H: third pleopod.

Diagnosis: Munnidae with eyes. Body covered 

densely with stout spines. Mandibular palp present, 

Goxal plates visible in dorsal view on peraeonal 

somites 2-7. Endite of second male pleopod curved, 

appendage pointed and hirsute. Lateral expansion 

lacking from apex of male first pieopods. First peraeopod 

stout, dactyl with two claws, other articles with 

many stout setae on inferior margin. Uropoda 

massive, with peduncle and biramous and dorsal 

insertion. 

Composition; The dorsal insertion of the massive 

uropods characterizes this genus, and it is therefore 

highly probable that Mormomunna Vanhoffen and 

Pseudomunna Hansen are synonyms. Hansen did not 

think so on the basis of the male first pieopods, but 

even within Munna the male first pieopods differ 

rather markedly. In the species which I have been 

able to examine I did not find the maxillipedal palp 

articles as narrow as indicated by Hansen for hystrix; 


they are nevertheless narrower than other Munnidae. 

The species range from bathyal to abyssal depths. 

LIST OF THE SPECIES OF ACANTHOMUNNA 



1. proteus 

2. spinipes 

3. hystrix 


ACANTHOMUNNA 

1281 2011 

385 385 

1505 1505 

I. Cephalon with spines on dorsum 2 

1. Cephalon without spines on dorsum 3 

2. With a central cluster of three spines . beddardi, n. sp. 

2. With one spine near each lateral 

border proteus Beddard 

3. First peraeonal somite with only four 

spines spinipes (Vanhoffen) 

3. First peraeonal somite with more than 

six spines hystrix (Hansen) 

Figure 58. Notoxenoides abyssi, n. sp. A: dorsal view male holotype; B: gnathopod; C: 

maxilliped; D: uropod; E: mandible; F: first pleopod; G: third pleopod.


Figure 59. Notoxenoides vemae, n. sp. A: dorsal view female holotype; B: dorsal view uropod; 

C: first peraeopod; D: first antenna; E: mandible; F: maxilliped; G: third peraeopod. 

Acanthomunna beddardi, new species 

Figure 57 


Diagnosis: Acanthomunna with bifurcated frons of 

cephalon and three stout spines in a cluster at midline 

of dorsum of cephalon. Three transverse rows of stout 

spines on dorsum of first three peraeonal somites and 

one row on somites 5 and 6. Pleon irregularly spinous. 

Propod with seven stout spines along inferior margin. 






Affinities: This species is distinct in having the 

central cluster of three spines in the dorsum of 

cephalon. 

NOTOXENOIDES, new genus 

Type species: Notoxenoides abyssi, new species. 


Diagnosis: Munnidae with coxal plates evident in 

dorsal view on peraeonal somites 5-7 inclusive. 

Uropoda biramous small, leaf-like, peduncle lacking, 

insertion lateral. Lateral borders of peraeonal somites 

1-7 inclusive produced into spine-like process, dorsum 

at midline of each somite with a long spine. Maxillipedal 

palp narrower than endite. Mandibular palp 

triarticulate; molar expanded and truncated at apex. 

Apex of male first pleopods triangulate. Ocular

peduncles narrow and curved forward in front of 

cephalon, ocelli lacking. 

Composition: Known from type species and the one 

other new species described herein. Pleurogonium 

pulchrum Hansen possibly belongs to this genus. 

Notoxenoides abyssi, new species 

Figure 58 


Diagnosis: Notoxenoides with a produced, pointed, 

spinulate pleon. Flagellum of first antenna with 

four articles. Dorsum of pleon without spines, 

lateral border spinulate. Propod with only a stout 

seta on inferior margin. Ocular peduncles projecting 

in front of cephalon. Second article of peduncle of 

first antenna with a spine at distal outer margin. 

Measurements: Length holotype male 1.9 mm., 

width pleotelson 0.44 mm., length gravid allotype 

2.0 mm., width pleotelson 0.5 mm. 


No. 54, types plus two male and one female paratypes, 

cat. no. 1-181. 


Affinities: The species resembles Pleurogonium pul- 

Diagnosis: Paraselloidea with free cephalon. Eyes 

lacking, mandible with tapering yet blunt molar, palp 

present. Uropod with long peduncle. None of the 

peraeopods modified for swimming; dactyl of sixth 

with two claws. Last two articles of maxillipedal palp 

one-half the width of first three; second \ the width of 

endite. Somites of peraeon much wider than long. 

Pleon with two somites. 

Composition: The family probably contains Jolanthe 

Beddard, Microprotus Richardson, and Katianira 

Richardson. Janthopsis and Rhacura probably belong 

to the Ianirellidae (Menzies, in press). The family is 

related to the Ianirellidae, but the maxillipedal palp 

articles are too narrow and it has two somites to the 

pleon instead of only one. The very long uropodal 

peduncle characterizes members of the family. 

Genus: ACANTHASPIDIA Stebbing 

Type species: Acanihoniscus typhlops G. O. Sars, 

1879, p. 434. 

Synonym: Acanthoniscus G. O. Sars, 1879, p. 434, 

— 1885, p. 119, PI. X. Acanthaspidia Stebbing, 1893, 

p. 378. 

Diagnosis: Acanthaspididae with mandible having 

triarticulate palp and lacinia and setal row. Uropoda 

biramous, with long peduncle, insertion terminal. 

Maxillipedal palp with expanded first three articles all 


chrum Hansen, 1916, in having the dorsal spines on the 

body. The mandibles would obviously distinguish 

the two, but Hansen did not describe them for 

pulchrum. Its nearest abyssal relative is the following 

new species. 

Notoxenoides vemae, new species 

Figure 59 


Diagnosis: Notoxenoides with apex of pleon pointed 

but not strongly produced. Flagellum of first antenna 

with four articles. Dorsum of pleon without spines, 

lateral border spinulate. Propod with a curved spine 

and one stout seta on inferior margin. Ocular 

peduncles (?) directed laterally. Second article of 

peduncle of first antenna without spines. 

Measurements: Female holotype length 1.8 mm, 

width at widest point 0.8 mm. 




Affinities: Related to N. abyssi Menzies and P. 

pulchrum Hansen, but with sharp laterally directed 

ocular peduncles. 

ACANTHASPIDIDAE, new family 

less than one-half the width of endite. Cephalon 

without eyes or eye stalks. Peraeonal somites provided 

with spine-like lateral expansions. Coxal plates 

visible in dorsal view on somites 5-7 inclusive. Pleonal 

lateral margin with many spine-like projections. 

Composition: The genus contains three species 

besides the new one described here: 



1. typhlops (G. O. Sars) 823 1354 

2. decorata (Hansen, 1895) 4000 4000 

3. drygalskii Vanhoffen 350 385 


ACANTHASPIDIA 

1. Body with a single median row of single spines . . 2 

1. Body with a pair of spines on 

midline drygalskii Vanhoffen 

2. Frons bifid 3 

2. Frons with single frontal horn . . . . decorata Hansen 

3. Lateral border fifth peraeonal somite 

trifid typhlops (G. O. Sars) 

3. Lateral border of fifth peraeonal somite 

with one large spine and a small one . bifurcata, n.sp. 

Acanthaspidia bifurcata, new species 

Figure 60 


Diagnosis: Acanthaspidia with bifurcating rostrum,


Figure 60. Acanthaspida bifurcata, n. sp. A: in toto, type; B: third pleopod of female; 

C: uropodal rami; D: first antenna; E: maxilliped; F: first peraeopod; G: fifth peraeopod; 

H: apex of molar of right mandible; I: right mandible; J: ventral surface of 

pleotelson. 

first six peraeonal somites each with a mid-dorsal 

spine. Last three peraeonal somites with one spinelike 

lateral expansion and smaller tooth. Each lateral 

border of pleon with seven spine-like projections 

alternating in size. Maxilliped with two coupling 

hooks. Flagellum of first antenna with eight articles. 


width pleotelson 1.5 mm., and one fragmentary 

female paratype. 




Affinities: Related to typhlops but with fewer 

peraeonal spine-like lateral extensions. 

Acanthaspidia decorata Hansen 

Figure 61 A 

Synonyms: Acanthaspidia decorata Hansen, 1895, 

pp. 6-7, PI. I. 

Diagnosis: Acanthaspidia with mid-frontal projection 

a simple spine. Each peraeonal somite with a

ingle mid-dorsal spine except fourth, which has two. 

iach lateral border of pleon with eight spines; apex 

oncave. Lateral borders of somites 5—7 with only 

ne large spine-like extension. Flagellum of first 

mtenna with ten or more articles. 

Measurements: Male length 9.7 mm. (Hansen, op. 

•it.). 

Type locality: Plankton Expedition, North Atlan- 

Synonyms: Abyssianiridae Menzies, 1956a, pp. 12- 

.3. 

Diagnosis: Paraselloidea with free head. Manlibles 

normal, molar process expanded and truncated 

it apex. First antenna shorter than body. Peraeonal 

>omites all of similar length, none fused. Peraeopods 

2-7 -simple walking legs, two claws on dactyls, not 

:hree, no legs modified for swimming. First peraeopod 

prehensile. Coxal plates rounded, not spiniform, 

visible in dorsal view. Pleon with two somites. 

Uropoda biramous, inserting dorsally with short 

peduncle. Maxillipedal palp with first three articles 

as wide as endite. (Modified after Menzies, 1956a.) 

Composition: Formerly this family contained only 

the type genus. It is now possible to add one new 

genus, Xostylus, with a single new species. The family 

is closely allied to the Munnidae through the genus 

Austrosignum, which may ultimately have to be 

transferred to the Abyssianiridae. 

Genus: ABYSSIANIRA Menzies 

Synonyms: Abyssianira Menzies, 1956a, p. 14. 

Type species: Abyssianira dentifrons Menzies, 1956a, 

p. 15. 

Diagnosis: Abyssianiridae with coxal plates visible 

in dorsal view on peraeonal somites 2-7 inclusive. 

Lateral margins of cephalon flattened and expanded. 

Abyssianira dentifrons Menzies 

Figure 61 B-H 

Synonyms: Abyssianira dentifrons Menzies, 1956a, 

p. 15. 

Diagnosis: Abyssianira with denticulate body margins. 

Cephalon expanded, flattened rostrum, and 

lateral horns. Pleotelson lateral border denticulate, 

I apex rounded. First antenna with six articles, last 

about one-third shorter than penultimate article. 

Male first pleopod with three setae at each angle on 

either side of sympod. Maxilliped with two coupling 

hooks. Mandible with triarticulate palp, last article 

with two apical setae. Uropodal exopod one-half the 



Family: ABYSSIANIRIDAE Menzies 

tic, Station 158, latitude 7.5° N., longitude 21.3° W., 

4000 meters. 

Distribution: Known only from type locality. It 

was not collected by Vema. 

Affinities: The simple spine at the frons of the 

cephalon and the concave apical margin on the pleon 

distinguish this species. 


width at second peraeonal somite 0.85 mm. 



Distribution: Also found at South Atlantic, L.G.O. 

Biotrawl No. 214, one female, cat. no. 1-203; L.G.O. 

Biotrawl No. 12, one male, two females, cat. no. 1-90.; 

L.G.O. Biotrawl No. 51, one fragment, cat. no. 1-185. 

Affinities: This species is closely allied to A. 

argentenensis, from which it differs in having the apex of 

the pleon smooth, not spinulate. 

Abyssianira argentenensis, new species 

Figure 61 I-L 


Diagnosis: Abyssianira with quadrate pleotelson. 

First antenna with six articles, last article subequal in 

length to penultimate article. Propod of first 

peraeopod with only one stout two-pointed seta. Apex 

of pleon spinulate. Uropodal exopod two-thirds the 



pleon 0.5 mm. 

Type locality: North Atlantic, holotype, L.G.O. 

Biotrawl No. 207, cat no. 1-218. 


Affinities: Closely related to A. dentifrons, from 

which it differs in having the apex of the pleon 

spinulate. 

XOSTYLUS, new genus 

Type species: Xostylus parallelus, new species. 

Diagnosis: Abyssianiridae with coxal plates visible 

in dorsal view on last three peraeonal somites only. 

Lateral margins of cephalon not flattened and expanded. 

Composition: Monotypic. 

Affinities: Closely related to Abyssianira but resembling 

the Nannoniscidae in general body shape. The 

peraeopods are ambulatory and none is modified for 

swimming; the mandibular molar is stout and truncated 

at the end.


Figure 61. A: Acanthaspida decorata Hansen, dorsal view. B-H: Abyssianira dentifrons Menzies. 

B: dorsal view male holotype; C: mandible; D: lateral border of pleotelson; E: second 

pleopod; F: first peraeopod; G; first pleopod; H: third pleopod. I-L: Abyssianira 

argentenensis, n. sp. I: uropod dorsal view; J: first antenna; K: first peraeopod; L: dorsal 

view female holotype. M-R: Xostylus parallelus, n. sp. M: dorsal view female holotype; 

N: sixth peraeopod; O: first antenna; P: mandible; Q_: second antenna; R: maxilliped.

Xostylus parallelus, new species 

Figure 61 M-R 


Diagnosis: Xostylus with lateral border of pleon 

smooth, apex curved evenly rounded, devoid of 

spines. Frons of cephalon straight. Flagellum of first 

antenna with six articles. Second article of mandibular 

palp with three characteristic stout spines. 

Diagnosis: Paraselloidea with cephalon free. Dactyls 

of peraeopods 2-7 inclusive with three claws (two 

major ones and an accessory one). Palp of maxilliped 

with last two articles narrow, others twice as wide and 

about equal to width of endite. Peraeopods all ambulatory, 

first often prehensile, none modified for 

swimming. Uropoda terminal biramous and with 

peduncle. Peraeonal somites all of similar length. 

Composition: This major heterogeneous family of 

the Paraselloidea is represented in the main by shallow 

water genera, viz.: lanira, laniropsis, Jaera, Caecijaera, 

Janiralata, Iathrippa, etc. Two genera contain abyssal 

species, lanira (one species only) and a new one 

described herein. 

Genus: IANIRA Leach 

Synonyms: lanira Leach, 1814, p. 434; — Sars, 

1897, p. 99. Henopomus Krayer, 1847, p. 366. 

Type species: lanira maculosa Leach. 

Diagnosis: Ianiridae with two-jointed pleon. 

Coxal plates visible in dorsal view on peraeonal somites 

2-7 inclusive. Mandible with expanded truncated 

molar, lacinia and setae row present, palp triarticulate. 

Exopod of third pleopod narrower than endopod. 

Apex of male first pleopod without lateral expansions. 

Second antenna with pronounced scale. First antenna 

shorter than second. Cephalon and pleon without 

pronounced lateral spine-like projections. 

Composition: Only one species in this genus is from 

the abyss. This is lanira maculosa Leach of Hansen, 

1916, which is here described as a new species. 

lanira hanseni, new species 

Figure 62 A-B 

Synonyms: lanira maculosa Leach, 1814, Hansen, 

1916, pp. 14-16, PL I. 

Diagnosis: lanira with a quadrate cephalon. Eyes 

removed from lateral border of cephalon. Apex of 

male first pleopod trilobed. Postero-lateral margin of 

pleon spinulate. 

Measurements: Female length 6.5 mm., male 

length 7.0 mm. (Hansen). 


Family: IANIRIDAE 

Epipod of maxilliped bottle-shaped; endite with four 

coupling hooks. 




12, type cat. no. 1-200. 



Type locality: North Atlantic, south of Iceland, 

Thor, latitude 60° 11' N., longitude 19° 36' W., 1899 

to 2143 meters, two specimens (Hansen, op. cit., p. 16). 


Affinities: This species, an eye-bearing abyssal 

species, shows a close resemblance to /. maculosa 

Leach from the shallow water. It is based only on 

Hansen's description and not on specimens examined 

by me. It differs markedly from maculosa in having the 

apex of the male first pleopod trilobed and not simply 

bilobed (viz., G. O. Sars, 1897, PL 40). It was not 

captured by Vema. 

ABYSSIJAERA, new genus 

Type species: Abyssijaera acarina, new species. 

Diagnosis: Ianiridae with pleon consisting of one 

somite only. Eyes lacking; mandibular molar reduced 

to a short spine; palp triarticulate; toothed 

incisor and lacinia present. Maxillipedal palp with 

first two articles expanded and as wide as endite. 

Coxal plates not visible in dorsal view on peraeonal 

somites. 

Composition: Monotypic. Most of the peraeopods 

were lacking from the single specimen. I am assuming, 

on the other characteristics and the basis of 

general similarity of the species to Jaera, that most the 

dactyls of peraeopods 2-7 are triunguiculate. Otherwise 

I should have to establish a new family for the 

animal. The genus is closely related to Jaera, differing 

mainly in having one pleonal somite, not two, and in 

having a much reduced mandibular molar process. 

Abyssijaera acarina, new species 

Figure 62 C-I 


Diagnosis: Abyssijaera with lateral margins of pleon 

each with nine setae, apex rounded, with nine setae. 

Apex of male first pleopod rounded each with nine 

setae. Maxilliped with two coupling hooks (uropoda 

missing). 


width pleon 0.32 mm.


Figure 62. A-B: Ianira hanseni, n. sp. A: dorsal view female from latitude 62° 11' N., 

longitude 19° 36' W., after Hansen; B: distal part of medium lamella of abdomen operculum 

of male from same location, after Hansen. C-I: Abyssijaera acarina, n. sp. C: dorsal view 

male holotype; D: maxilliped; E: first peraeopod; F: second antenna; G: mandible; 

H: third pleopod; I: first pleopod. J-M: Vemathambema elongata, n. sp. J: dorsal view 

female holotype; K: mandible; L: maxilliped; M: third peraeopod. N-O: Echinothambema 

ophiuroides Menzies. N: ventral view pleon; O: dorsal view ambisexual holotype.

Type locality: North Atlantic, L.G.O. Biotrawl No. 





Family: ECHINOTHAMBEMIDAE Menzies 

Synonyms: Echinothambemvdae Menzies, 1956a, pp. 

9-10. 

Diagnosis: Paraselloidea with fused or free head, 

eyes lacking. Mandibles normal, molar process well 

developed and expanded a truncated apex. Antennae 

shorter than body, about twice the length of cephalon. 

All peraeopods simple, 2-7 simple walking legs; dactyl 

with two terminal claws. Uropoda terminal with 

peduncle. Last one or two peraeonal somites fused 

with pleon. First three articles of maxillipedal palp 

expanded, as wide as endite. Coxal plates lacking. 

First peduncular article of first antenna much 

expanded. Anus contained within the branchial 

chamber. 

Composition: Formerly monotypic (Menzies, 1956a, 

p. 10). A new genus is added here and the diagnosis 

has accordingly been altered to allow its inclusion. 

Genus: ECHINOTHAMBEMA Menzies 

Type species: Echinothambema ophiuroides Menzies 

1956a, p. 11. 

Synonyms: Echinothambema Menzies, 1956a, pp. 

10-11. 

Diagnosis: Same as for family. Mandible without 

palp. 

Composition: One abyssal Atlantic species. 

Echinothambema ophiuroides Menzies 

Figure 62 N-O 

Synonyms: Echinothambema ophiuroides Menzies, 

1956a, p. 11. 

Diagnosis: Echinothambema with first antenna with 

six articles, last one-third longer than penultimate 

article. Lateral borders of peraeonal somites each 

with expanded and pronounced margin bearing a 

single stout seta. Body sharply granulate. Maxilliped 

with two coupling hooks. Cephalon at antero-lateral 

Diagnosis: Paraselloidea with cephalon free, eyes 

lacking. Mandibles normal, molar process well 

developed and expanded at truncated apex. Antennae 

shorter than body. All peraeopods simple walking 

legs, dactyls with two terminal claws. Uropod absent. 

Pleon with one somite only. All peraeonal somites 

distinct. First three articles of maxillipedal palp as 

wide as endite. Coxal plates lacking. 

margin with a pair of swellings, each bearing a stout 

seta. Mandibles without a palp. 

Measurements: Holotype ambisexual 5.00 mm. 

long, 1.5 mm. wide. 





VEMATHAMBEMA, new genus 

Type species: Vemathambema elongata, new species. 


Diagnosis: Echinothambemidae with cephalon 

fused to first peraeonal somite and last somite of 

peraeon fused to pleon. First article of first antenna 

not expanded but stout and elongated as long as 

second. 

Composition: Monotypic abyssal. 

Affinities: Related to Echinothambema in the absence 

of coxal plates and the fusion of peraeonal 

somite 7 with the pleon and in the absence of a 

mandibular palp. Uropoda (missing) probably with 

peduncle. 

Vemathambema elongata, new species 

Figure 62 J-M 


Diagnosis: Vemathambema with smooth pleon, apex 

rounded, body without spines or setae. Frons of 

cephalon concave, devoid of spines or setae 

Measurements: Holotype female length 5.2 mm 






Family: THAMBEMATIDAE 

Composition: Monotypic. The family resembles 

the Jaeropsidae in many significant respects, 

notably in the details of the structure of the 

maxillipeds and the shape of the front of the 

head and the antennae structure. The mandibular 

structure, however, clearly indicates its distinctiveness.


Genus: THAMBEMA Stebbing 

Type species: Thambema amicorum Stebbing, 1912, 

p. 42; 1913, p. 237. 

Synonyms: Thambema Stebbing, 1912, p. 42; — 

1913, pp. 237-239. 

Diagnosis: Same as for the family. 

Composition: Monotypic. 

Thambema amicorum Stebbing 

Figure 63 

Synonyms: Thambema amicorum Stebbing, 1912, p. 

42; — 1913, pp. 237-239, PI. 26. 

Diagnosis: Thambema with frons of cephalon convex 

and even, pleon without spines or serrations, apex 

evenly rounded. Apex of male first pleopod pointed 

without lateral expansions. Second article maxillipedal 

palp wider than third, fourth and fifth very 

narrow. 

Measurements: About 8 mm. (Stebbing, 1913, p. 

239). 

Type locality: North Atlantic, west of Donegal, 

Porcupine Station 19, latitude 54° 53' N., longitude 

10° 56' W., 2486 meters. 

Distribution: Known only from type locality. Not 

captured by Vema. 

Genus: MESOSIGNUM, new genus 

INCERTAE 


Type species: Mesosignum kohleri, new species. 

Diagnosis: Paraselloidea with free cephalon. All 

peraeopods ambulatory. Mandible with a triarticulate 

palp and a toothed incisor, setal row present, lacinia 

present, molar tapering to a flat setiferous point. 

Uropods uniramous, with peduncle, insertion lateral. 

Maxillipedal palp with narrow articles all of similar 

width and one-half the width of endite. First male 

pleopod rounded at apex. Cephalon without eyes or 

eye stalks. First antenna about twice the length of 

cephalon. Peraeonal somites, except first provided 

with spine-like lateral expansions. Coxal plates 

visible in dorsal view only on somites 5—7 inclusive. 

Anus separated from branchial cavity. 

Remarks: The mandibles of this genus resemble 

Pleurosignum (Pleurogonidae), whereas the maxillipedal 

palp is like the Dendrotioniidae. The epimeral 

plates are like Austrosignum (Pleurogonidae); whereas 

the uropods are unique. Assignments of the genus to 

an existing family is impossible and the establishment 

of a new one seems not warranted at this time. 

Composition: The genus Mesosignum contains two 

species, both abyssal and bathyal; both are new and 

from the Caribbean. 

Figure 63. Thambema amicorum Stebbing. A: 

maxillipeds; B: dorsal view cephalon; G: 

third pleopod; D: mandible; E: second 

pleopod; F: first gnathopod; G: dorsal view 

pleon; H: first pleopod. 

SEDIS 


MESOSIGNUM 

Apex of pleon rounded kohleri, n. sp 

Apex of pleon bifurcated by stout spine-like 

projections usheri, n. sp 

Mesosignum kohleri, new species 

Figure 64 A-G 


Diagnosis: Mesosignum with apex of pleon evenlv 

rounded, postero-lateral projections lacking. Frons of 

cephalon pointed. Antero-lateral spine of seconc 

somite only twice the length of postero-lateral spine 

and not extending forward beyond peduncle of first 

antenna. Apex of male first pleopod rounded with 

ten marginal setae. 


width pleotelson 0.35 mm., allotype gravid length 2.3 

mm., width pleotelson 0.30 mm. 


Biotrawl No. 96, types plus one male, three female 

paratypes, cat. no. 1-82. 

Distribution: L.G.O. Biotrawl No. 94, three males, 

two females, two juveniles, one fragment, cat. no. 

1-84; No. 95, three males, cat. no. 1-83; No. 97, one 

female, cat. no. 1-85; No. 98, two males, cat. no. 1-86.


Figure 64. A-G: Mesosignum kohleri, n. sp. A: mandible; B: uropod; C: first pleopod; 

D: dorsal view male holotype; E: maxilliped; F: first peraeopod; G: third pleopod. 

H-J: Mesosignum usheri, n. sp. H: dorsal view male holotype; I: first pleopod; J: uropod. 

Affinities: Near to usheri but without stout spine at 

postero-lateral angle of pleon. 

Mesosignum usheri, new species 

Figure 64 H-J 


Diagnosis: Mesosignum with stout spinulate posterolateral 

spines at apex of pleon. Frons of cephalon 

evenly rounded. Antero-lateral spine of second 

peraeonal somite five times the length of posterolateral 

spine and extending forward beyond peduncle 

of first antenna. Apex of male first pleopod straight, 

with eight marginal setae. 





Biotrawl No. 98, types plus one female, cat. no. 

1-87-88. 


Affinities: Near to kohleri but with stout spine at 

postero-lateral angles of pleon.


The three subtribes of the Flabellifera have been 

reported from the abyss, where each is represented 

by several species. The subtribes are the Anthuroidea, 

the Seroloidea, and the Cirolanoidea. It is highly 

probable that the records of the latter are due to 

pelagic species caught on the way up. 

Diagnosis: Flabellifera with the fourth and fifth 

pairs of pleopoda large and operculiform, pleopods 

1-3 normal, smaller than 4 and 5. Cephalon united 

medially with first peraeonal somite. Body strongly 

depressed, much wider than high (thick). Uropoda 

small, normal, subapical, not arching over pleon. 

(From Menzies, in press.) 

Composition: The serolids have been revised by 

Nordenstam (1933). The majority of the species have 

been recovered from shallow water, and although a few 

abyssal species have been described, only one— 

Serolis neaera Beddard—had been known from the 

Atlantic abyss. The genus is well represented in 

Antarctic polar regions, but is yet unknown from the 

Arctic. In fact, only one species is known from 

the Northern hemisphere—namely, Serolis carinata 

Lockington (Richardson, 1905). Here five species of 

abyssal serolids are described from the abyss of the 

South Atlantic. 

Genus: SEROLIS Leach 

Subgenus: SEROLIS Nordenstam, 1933 

Type species: Serolis (Serolis) paradoxa (Fabricius, 

1775). 

Diagnosis: Uropoda two-branched (biramous, not 

spiniform). Tergum of seventh peraeonal somite 

vanished. Tergum of sixth peraeonal somite well 

demarcated from first abdominal segment in its 

entire length. Second article of maxillipedal palp 

cordate. (Modified after Nordenstam, 1933.) 

Serolis (Serolis) neaera Beddard 

Figure 65 A 

Synonyms: Serolis neaera Beddard, 1884, pp. 331-332. 

Diagnosis: Serolis with coxal plates marked off on 

Tribe: FLABELLIFERA 

Family: SEROLIDAE 

A KEY TO THE FLABELLIFERAN SUBTRIBES 

(From Menzies, in press) 

1. Individual peraeonal somites longer than 

wide Anthuroidei 

1. Individual peraeonal somites much wider than 

long 

2. Peraeon with first somite fused medially with 

cephalon. First to third pleopoda smaller than 

operculiform fourth and fifth pairs Seroloidtc 

2. Peraeon and cephalon not fused. Pleopods all 

similar in size Cirolanoida 

peraeonal somites 2-4 inclusive. Third article of 

maxillipedal palp small. Pleon with apex acute, 

dorsum with stout wide tooth at proximal end and a 

Figure 65. A: Serolis (Serolis) neaera Beddard, 

dorsal view. B: Serolis (Serolis) margaretae, 

n. sp., dorsal view female holotype. 

smaller one near midpoint having a tooth on either 

side and a carina connecting with paired converging 

carinae near proximal tooth. Second pleonal epimera 

extending beyond posterior margin of pleon. 

Uropoda biramous, extending beyond apex of pleon.


Figure 66. Serolis (Serolis) macdonnellae, n. sp. A: dorsal view female holotype; B: maxilliped 

embryo; C: first peraeopod; D: dorsal view embryo; E: maxilliped; F: peraeopodal 

seta; G: first pleopod. 

Measurements: Largest male length 43 mm., greatest 

breadth 47 mm; female length 40 mm., greatest 

breadth 40 mm. 

Type locality: South Atlantic, Challenger Station 

320, 1079 meters, and Station 318, 3731 meters. 

Distribution: This species was not captured by 

Vema. 

Serolis (Serolis) margaretae, new species 

Figure 65 B 



peraeonal somites 2-5. Third article of maxillipedal 

palp small. Uropods biramous. Pleon with sharp 

pointed median extension of mid-dorsal carina, lateral 

carinae lacking. First peraeonal somite without spine 

at antero-lateral border, which is smooth. Eye lobes 

present, cephalon with low mid-dorsal tubercle at 

posterior end. Each peraeonal somite with a tubercle 

near posterior margin at midline. Pleon lacking 

postero-lateral angles. Epimera of sixth peraeonal 

somite extending slightly beyond apex of pleon.

188 

Uropodal rami blunt, endopod one-fourth longer 

than exopod. 


width pleon 3.2 mm., plus three smaller female 

paratypes. 


200, types only, cat. no. 1-226. 


Affinities: The very short uropodal exopod distinguishes 

this species. 

Serolis (Serolis) macdonnellae, new species 

Figure 66 


Diagnosis: Serolis with coxal plates marked off 


on peraeonal somites 2-4 inclusive. Third article of 

maxillipedal palp small. Pleon with sharp median 

posterior extension of entire mid-dorsal carina; 

lateral carinae lacking; postero-lateral angles and 

dorsal sculpture lacking; a pit present on either side 

of midline dorsally. Cephalon with sharp separated 

antero-lateral angles; lateral area carinate. Eye 

lobes present. Uropodal rami blunt, exopod onefifth 

shorter than endopod, not extending to pleonal 

posterior margin. 

Measurements: Length holotype female 42 mm., 

width pleotelson 13 mm. 




Affinities: Similar to S. (S.) glacialis Beddard but 

Figure 67. Serolis [Serolis) vemae, n. sp. A: dorsal view male holotype; B: peraeopodal seta; 

C: maxilliped; D: uropod; E: apex of second pleopod; F: first peraeopod; G: ventral 

view peraeon-pleon.

differing in the sculpture on the dorsum of the 

pleon. 

Serolis (Serolis) vemae, new species 

Figure 67 



peraeonal somites 2-5 inclusive. Third article of 

maxillipedal palp small. Uropoda biramous, exopod 

minute, endopod thick projecting beyond posterior 

margin of pleon. Pleon without postero-lateral angles, 

apex pointed, mid-dorsal carina entire, lateral or 

transverse carinae lacking. Lateral borders of peraeon 

not pointed and produced but quadrate. Peraeonal 

somites 5 and 6 with a small mid-dorsal spine. Flagellum 

of second antenna shorter than last peduncular 

article. Flagellum of first antenna with ten articles. 

Measurements: Hoiatype male 4.3 mm., width 

1.7 mm. 



Distribution: Also from L.G.O. Biotrawl No. 51, 


Affinities: This species is unique, not falling into any 

of the subgroups mentioned by Nordenstam (1933). 

Serolis (Serolis) maryannae, new species 

Figure 68 


Figure 68. Serolis (Serolis) maryannae, n. sp.. 

dorsal view female holotype. 



peraeonal somites 2-5. Third article of maxillipedal 

palp small. Uropoda biramous. Pleon with sharp 

pointed median posterior extension of mid-dorsal 

carina; lateral carinae lacking. First peraeonal 

somite with pronounced spine at antero-lateral angle. 

Eye lobes present, cephalon with mid-dorsal tubercle 

at posterior end. Each peraeonite except first somite 

with tubercle at posterior border at midline. Pleon 

lacking postero-lateral angles. Epimera of sixth 

peraeonal somite extending beyond apex of pleon by 

one times its length. Uropodal rami blunt, exopod 

one-third shorter than endopod, not extending to 

posterior margin of pleon. 

Measurements: Female holotype length 18.8 mm, 





Affinities: The serrated pleonal apex of this species 

is unique. Otherwise the species is very close to S. 

(S.) macdonnellae. 

GLABROSEROLIS, new genus 

Type species: Glabroserolis specialis, n. sp. 

Diagnosis: Serolidae with uniramous uropoda. 

Coxal plates not marked off on any peraeonal somite. 

First antenna one-half the width of expanded peduncular 

article of second. Second article of maxillipedal 

palp quadrate, not cordate. Basipodites of pleopods 

1-3 with projecting setiferous inner proximal angles. 

Composition: Unique. 

Glabroserolis specialis, new species 

Figure 69 


Diagnosis: Glabroserolis with shield-shaped pleon 

devoid of carinae or postero-lateral angles. Endopod 

of uropod pointed, one-third longer than peduncle, 

not visible in dorsal view. Lateral borders of peraeon 

quadrate, not projecting. Flagellum of second antenna 

shorter than last peduncular article. 




53, type and one female, one fragment, cat. no. 

1-194. 


Affinities: A unique species in a unique genus. To 

a certain extent the genus resembles Spinoserolis 

Nordenstam, but it lacks coxal plate demarcation 

entirely and has the unusually expanded peduncular 

articles of the second antenna.


Figure 69. Glabroserolis specialis, n. sp. A: dorsal view female holotype; B: first pleopod; 

C: uropod; D: maxilliped; E: second pleopod; F: peraeopodal seta; G: peraeopod. 

Anthurids are seldom encountered in the abyss and 

are principally shallow water representatives. In 

the Atlantic four species, Calathura brachiata (Stimpson, 

vide Hansen, 1916), Hyssura producta Norman and 

Stebbing, Ananthura abyssorum (Norman and Stebbing), 

and Anthelura truncata (Hansen). The standard 

reference is Barnard's synopsis of the group. Here 

Pseudanthura lateralis Richardson is described from 

1800 meters and a new species of Leptanthura is described 

from greater depth. 

Diagnosis: Flabellifera with the individual peraeonal 

somites much longer than wide. Generally the 

uropoda arch over the telsonic somite (in all genera 

except Pseudanthura). The terminal abdominal segment 

(seventh) is probably a false telson or pseudotelson. 

First peraeopod generally subchelate. 

Subtribe: ANTHUROIDEA 


THE ANTHUROIDEA HAVING 

ABYSSAL SPECIES 

(After Barnard, 1925) 

1. Mouth parts adapted for piercing and sucking . . 2 

1. Mouth parts adapted for chewing 3 

2. Uropoda lateral, exopod minute, not inflexed 

over pleotelson Pseudanthura 

2. Uropoda with exopod inflexed over pleotelson . . 5 

3. First pleopod indurated, operculiform . . . . Hyssura 

3. First pleopod similar to second, not operculiform . 4 

4. Peraeopods 2-3 not large Anthelura 

4. Peraeopods 2-3 very similar to 1, large 

Ananthura 

5. Maxilliped with three articles Leptanthura 

5. Maxilliped with five articles Calathura

Genus: PSEUDANTHURA Richardson 

Type species: Pseudanthura lateralis Richardson, 

1911, pp. 523-524; — Barnard, 1920, pp. 343-344. 

Diagnosis: Eyes absent. Mouth parts adapted for 

piercing and sucking. Telson not indurated, without 

statocyst. Maxilliped with four articles (palp with two 

articles). Peraeopods 4-7 with fifth joint not underriding 

the sixth. Uropoda with small, lateral exopod; 

endopod and peduncle fused. All somites of pleon 

distinct dorsally and laterally. (Modified after 

Barnard 1925.) 

Composition: The maxilliped in this genus has four 

articles not three, as indicated by Barnard (1925). 

The fusion of the uropodal endopod with the peduncle 

and the minute lateral exopods characterize 

this genus quite firmly. The genus contains only one 

species, and it ranges in depth from shallow water 

(930 meters) into the abyss (3200 meters). 

Pseudanthura lateralis Richardson 

Figure 70 

Synonyms: Pseudanthura lateralis Richardson, 1911, 

pp. 524-525; — Barnard, 1920, pp. 344-345, PI. 

XV; — 1925, p. 157. 

Figure 70. Pseudanthura lateralis Richardson, 

1911. A: dorsal view male; B: cephalon; 

C: uropod; D: fifth peraeopod; E: mandible; 

F: maxilliped. 


Diagnosis: Pseudanthura with a pair of stout 

tubercles medially at anterior border of peraeonal 

somites 3 and 4. Lateral border of uropodal endopod 

finely serrated. Apex of pleon pointed, without teeth 

or setae. 

Measurements: Male length 16 mm., female length 

18 mm. (Barnard, 1920). Richardson gave the length 

as 20.5 mm. 

Type locality: Coast of Soudan between Dakar and 

Praya, Talisman Station 80 (930 meters), Station 83 

(1139 meters), and Station 101 (3200 meters) 

(Richardson, 1911). 

Distribution: Near Dakar, West Africa (930-3200 

meters) and Cape Point, North Africa, 86° E., distant 

43 miles, 1620-1800 meters (Barnard, 1920, p. 345). 

L.G.O. Biotrawl No. 54. 

Remarks: While I am reasonably certain that the 

species described here is equal to Barnard's specimens, it 

may not be the same as Richardson's species. Richardson's 

(1911) description is incomplete and she gave no 

illustrations. The genus, however, is probably correct. 

Genus: CALATHURA Norman and 

Stebbing, 1886 

Type species: Calathura brachiata (Stimpson, 1853). 

Diagnosis: Mouth parts piercing and sucking. 

Eyes absent or feebly developed. Peraeon not 

strongly keeled dorso-laterally, with dorsal pits; 

seventh somite short. Pleon with distinct somites. 

Maxilliped with five articles. Peraeopods 4-7 with 

fifth joint triangular, underriding sixth. Pleopod 1 

not indurated. Uropods with broad exopod inflexed 

over telson. (After Barnard, 1925.) 

Composition: Restricted to the type species only by 

Barnard. The genus is known only from the northern 

hemisphere. 

Calathura brachiata (Stimpson) 

Figure 71 

Synonyms: Anthura brachiata Stimpson, 1853, p. 43; 

— Richardson, 1905, p. 72 and references. Calathura 

brachiata (Stimpson), Norman and Stebbing, 1886, 

pp. 131-133, PL XXVI, Fig. 1; —Richardson, 1905, 

p. 72 and references; — Hansen, 1916, pp. 183—184, 

PI. XV and references; — Barnard, 1925, p. 152. 

Paranthura norwegica Sars, 1873, p. 88. Paranthura 

arctica Sars, 1877, p. 347. 

Diagnosis: Single species with generic characteristics 

sufficient to distinguish it (cf. Barnard, 1925, p. 

152). Telson ovate-lanceolate, widest in the middle, 

apex acute, strongly concave dorsally in a longitudinal 

section, but plane in transverse section, a short 

narrow keel at base bearing a very fine median groove, 

followed by a very shallow ovate depression. (Barnard, 

op. cit., p. 152.)


Measurements: 45.5 mm. (Barnard, op. cit., p. 

152). 

Type locality: Duck Island, Bay of Fundy (Hargar, 

1880). 

Distribution: North Atlantic and Arctic, 5-735 

fathoms (Barnard, op. cit., p. 152). 

Figure 71. Calathura brachiata (Stimpson). A: 

dorsal view; B: cephalon; G: first antenna; D: 

statocyst; E: second antenna (Hansen, 1916). 

According to Hansen (1916, p. 184), the species 

was collected at several Ingolf stations, and he reports 

the species from 2488 meters at latitude 48° 38' N., 

west of Brittany (Norman and Stebbing, 1869, p. 

133). It is doubtful that this abyssal record is correct, 

but without specimens it is impossible to tell. 

Genus: ANTHELURA Norman and Stebbing, 

1886 

Type species: Anthelura elongata Norman and 

Stebbing, 1886. 

Diagnosis: Eyes absent. Peraeonal somites without 

dorsal pits. Pleon distinct at least laterally. 

Telson not indurated, moderately convex. Antenna 1 

typically with brush-like flagellum in male, pauciarticulate 

in female. Antenna 2 with flagellum pauciarticulate. 

Maxilliped five-jointed. Peraeopods 4-7 

with fifth joint not underriding sixth. Pleopod 1 not 

indurated. Exopod inflexed over telson. (After 

Barnard, 1925.) 

Composition: The genus contains the type, from 

1332 meters in the North Atlantic; Anthelura ramipies 

Barnard, from around 300 meters in the South 

Atlantic; and Anthelura truncata (Hansen) from the 

North Atlantic abyss. Here only the latter will be 

considered. 

Anthelura truncata (Hansen) 

Figure 72 A 

Synonyms: Cyathura truncata Hansen, 1916, p. 182, 

PI. XV. Anthelura truncata (Hansen), Barnard, 1925, 

p. 135. 

Diagnosis: Anthelura with third palpal joint of 

mandible shorter than first, tipped with a few setae. 

Maxilliped without inner plate. Antenna 1 with twojointed 

flagellum. Peraeopod 1 with fifth joint squarely 

projecting, palm slightly sinuous. Peraeopods 4-7 

with fifth and sixth joints narrow. Telson broadly 

ovate, widest at basal third, with straight lateral 

Figure 72. A: Anthelura truncata (Hansen), 

dorsal view of fragment. B-C: Ananthura 

abyssorum (Norman and Stebbing). B: cephalon; 

C: uropods. D-E: Hyssura producta 

Norman and Stebbing. D: cephalon; E: 

uropods. F: Mesidothea magalura polaris 

Gurjanova, dorsal view posterior. G: Mesidothea 

megalura megalura (G. O. Sars), dorsal 

view. 

margins and truncate apex, dorsal surface convex. 

Uropod with endopod ovate, apex rounded, exopod 

ovate. (After Barnard, 1925.) 

Measurements: To 10 mm. (Hansen, op. cit.). 

Type locality: North Atlantic, Ingolf Station 24. 

Davis Strait, latitude 63° 06' N., longitude 56° 00' W., 

2258 meters, temperature 2.4° C, five specimens.

Distribution; Also found at Ingolf Station 36, latitude 


1.5° C, two specimens (Hansen, op. cit.). 

Genus: ANANTHURA Barnard, 1925 

Type species: Ananthurasulcaticaudafta.ma.rd, 1925, 

p. 136. 

Diagnosis: Anthuroidea with chewing mouth 

parts. Eyes feeble or absent. Peraeon not dorsolateral^ 

keeled, dorsal pits in one species. Pleonal 

somites distinct. Telson lenticular in cross-section, 

somewhat indurated. Mandible with first and third 

palpal joints subequal, latter with a comb of setae. 

Maxilliped five-jointed with small inner plate which 

may not be present in all species. Peraeopods 2 and 3 

nearly as large as peraeopod 1. Peraeopods 4-7 with 

fifth joint short but not underriding sixth. Pleopod 1 

not indurated. Uropod with endopod long, subequal 

to peduncle, exopod closing over telson. 

Composition: Besides the bathyal Atlantic type, 

Barnard (1925) included two additional species, A. 

ovalis Barnard from the Mediterranean and the 

Atlantic abyssal Ananthura abyssorum (Norman and 

Stebbing), which is here described. 

Ananthura abyssorum (Norman and Stebbing) 

Figure 72 B-C 

Synonyms: Anthelura abyssorum Norman and Stebbing, 

1886, pp. 127-128, PI. 27. Ananthura abyssorum 

(Norman and Stebbing), Barnard, 1925, p. 137. 

Diagnosis: Ananthura with antennal flagella multiarticulate. 

Palm of first peraeopod with about eight 

slender spine-like setae. Palm of second pair with 

three spines and a few setae. Carpus and propod of 

last peraeopod each furnished with two forked spines 

on anterior margin. Telson with acute apex and equal 

in length to uropods. (From Norman and Stebbing, 

op. cit. p. 127.) 

Measurements: Length 9 mm. 

Type locality: North Atlantic near entrance of 

Davis Strait, Valorous Station 8, latitude 59° 11' N., 

longitude 50° 25' W., 3199 meters. 


Genus: HYSSURA Norman and Stebbing, 1886 

Type species: Hyssura producta Norman and Stebbing, 

1886. 

Diagnosis: Anthuroidea without eyes. Mouth part 

adapted for chewing. Dorso-lateral keels and pits 

lacking from peraeon. Telson indurated, without 

statocysts. Antennal flagellum pauci-articulate. Mandible 

with third palpal joint subequal to first, with 

comb of setae. Maxilliped five-jointed, with inner 


plate. Peraeopods 4-6 with fifth, joint not underriding 

sixth. Somite 7 without peraeopods. Pleopod 1 not 

operculiform, not larger than others. Uropods with 

narrow rami, exopod folding down over telson. 

Composition: The genus contains two deep sea 

species, producta and profunda Barnard. 

Hyssura producta Norman and Stebbing 

Figure 72 D-E 

Synonyms: Hyssura producta Norman and Stebbing, 

1886, pp. 128-129, PL 25; —Barnard, 1925, p. 137. 

Diagnosis: Hyssura with narrow cylindrical telson. 

Endopod of uropod terete, longer than peduncle; 

exopod very narrow, terete. Peraeopods 4-6 with 

fourth joint twice as long as broad. (After Barnard, 

1925.) 

Measurements: Length about one quarter of an 

inch. 

Type locality: North Atlantic, Valorous Station 11, 



Genus: LEPTANTHURA G. O. Sars 

Type species: Leptanthura tenius (Sars) 1872, Barnard, 

1925, p. 150. 

Diagnosis: Anthuroidea with piercing and sucking 

mouth parts, eyes absent. No dorsal pits. Pleon with 

distinct sutures. Telson shorter than pleon, concave 

dorsally, thin, not indurated; single statocyst at 

proximal end. Antenna 1 with brush-like flagellum in 

male, rudimentary in female. Flagellum antenna 2 

rudimentary in both sexes. Mandible with third 

palpal joint shorter than first, with two apical setae. 

Maxilliped three-jointed, second joint much the 

longest. Peraeopods 4-7 with fifth joint underriding 

sixth. Pleopod 1 not indurated. Uropods with endopod 

almost as broad as peduncle, exopod broadly oval, 

meeting at midline and folding down over telson. 

Composition: Besides the shallow water type, the 

genus also contains affinis (Bonnier), 1410 meters; 

glacialis Hodgson, 1910, from around 300 meters; 

orientalis Barnard, intertidal ?, thori Barnard, 952 

meters; laevigata (Stimpson), from around 200 meters; 

truncata Richardson, 1911, from 888 meters; chiltoni 

(Beddard, 1886), from around 1400meters; diemenensis 

(Haswell), littoral, and hendili Wolff from 6000 meters. 

Prior to this work an abyssal Atlantic species was 

unknown. 

Leptanthura species 

No figure 

Two specimens, a male and a female of a species of 

Leptanthura, were found in L.G.O. Biotrawl No. 22. 

They were too damaged to permit specific identification 

even though the generic designation was

194 


possible. This record is given here only to indicate previously only L. hendili Wolff from the Pacific 

that the genus does penetrate the Atlantic abyss; was known from abyssal depth. 

Cirolanid type isopods morphologically retain the 

greatest number of truly primitive and embyronal 

characters. Nevertheless, this type is not known for 

certain from depths exceeding 2000 meters. Two 

species, both members of the typically pelagic genus 

Eurydice, have been caught in dredge hauls fishing the 

depths and the surface in the Atlantic. These are: 

Eurydice grimaldi Dollfuss, Stephensen, 1915 (0-2600 

meters) and Eurydice stygia G. O. Sars, Hansen, 1916 

(527-2356 meters). 

The greatest depth from which Cirolanoidea are 

known is 1958 meters, based on the Challenger capture 

of the certainly benthic sphaeromid Naesicopea abyssorum 

Beddard from the South Pacific. The parasitic 

Anilocra meridionalis Searle, taken from 2000-2500 

Valviferans are in general alga feeders and are 

generally restricted to shelf depth, except for the 

Arcturidae, which contains filter-feeding types. These 

arcturids are quite common in shallow water, and one 

species, Antarcturus spinosus Beddard, has been reported 

from the abyss (2516 meters) in the South Atlantic 

Ocean. Four species of Antarcturus are known from 

Diagnosis: Valvifera with biramous uropods. Peraeopods 

2-4 directed toward the cephalon, provided 

with plumose setae, not prehensile. Last three peraeopods 

clinging or walking appendages. 

Composition: Stephensen (1947) has presented a 

review of the arcturids. The majority of the species 

are found in cold water and at shallow depths. The 

poles are typified by their own genera, Arcturus from 

the high northern latitudes and Antarcturus from high 

southern latitudes. Stephensen (op. cit.) has also 

provided a key to the 30 species of Antarcturus known 

up to 1940. 

Genus: ANTARCTURUS Zur Strassen, 1902 

Synonyms: Antarcturus, Nordenstam 1933, p. 122; 

— Stephensen, 1940, p. 17. 

Diagnosis: First peraeonal somite coalesced with 

cephalon, yet separated by a shallow groove. Lateral 

margins of the first peraeonai somite not prolonged 

Subtribe: GIROLANOIDEA 

Tribe: VALVIFERA 

Family: ARCTURIDAE 

meters in the South Pacific, should probably be 

included among the pelagic species. 

Anuropus, an exceedingly primitive genus (family: 

Anuropidae), has been identified as bathypelagic by 

Menzies and Dow (1958). 

Bathynomous is doubtless a truly benthic genus. The 

greatest depth from which it has been reported is 1719 

meters, and the shallowest is 357 meters. It is known 

mainly from the seas accessory to the oceans—e.g., 

Gulf of Bengal, Caribbean, South China Sea. Although 

very primitive, it has not succeeded in penetrating 

the abyss of the oceans. Perhaps it is best 

viewed as a relict descendant of the Mesozoic period. 

It is known as fossil from the Miocene of Japan 

(Imaizumi, 1953). 

the Antarctic abyss, and one is known from the Indian 

Ocean abyss. One species was present in the Vema 

collections from the South Atlantic. 

Besides the arcturids, Mesidothea has one subspecies 

which penetrates the abyss of the Arctic. 

Diagnosis: Isopoda with the uropods valve-like, 

flexed under the pleotelson as an operculum. 

downward and forward; mouth organs visible in 

lateral view. Pleon with three somites anterior to 

pleotelson, which are indistinctly marked off by 

shallow grooves. Length of pleon not exceeding 

length of the last five peraeonal somites together. 

Flagellum of second antenna with four or five articles. 

First peraeopods prehensile. Antennae as long as or 

longer than body. 

Type species: Arcturus furcatus Studer, 1884, pp. 

12-15, PI. I; — Zur Strassen, 1902, p. 686; — 

Nordenstam, 1933, p. 129. 

Antarcturus species 

No figure 

A large fragmentary specimen of a species of 

Antarcturus which is perhaps closely related to A. 

glacialis (Beddard) but with sharper and fewer dorsal 

spines was collected by Vema at L.G.O. Biotrawl No. 

214. The animal, with its pleon 9.7 mm. long, was

poorly preserved and description of it is not indicated 

at this time. It is mentioned here only because of its 

abyssal nature. 

Locality: South Atlantic, L.G.O. Biotrawl No. 

214. 

Genus: MESIDOTHEA Richardson 

Type species: Mesidothea entomon (Linnaeus), Richardson, 

1905, pp. 347-348. 

Diagnosis: Valvifera with uniramous uropoda. 

First antenna with four articles. Flagellum with a 

single article. Flagellum of second antenna multiarticulate. 

Peraeopods 1-3 prehensile without plumose 

setae. Pleon consisting of five complete 

somites. 

Composition: This genus formerly contained only 

two species—the blind sabini and the eye-bearing type, 

entomon. Gurjanova (1946, pp. 105-44) has provided a 

review of Mesidothea. She states, "A comparative 

analysis of species and forms of Mesidothea makes it 

possible to establish a continued row of morphological 

variations from the abyssal M. megalura megalura 

(G. Sars) through the intermediate M. megalura 

polaris Gurjanova, M. sabini megaluroides Gurjanova 

and M. sabini sabini to M. sabini robusta Gurjanova, and 

from M. sibirica (Birula) to M. entomon vetterensis 

Ekman, through the intermediate Far Eastern and 

Siberian estuary forms." This statement favors a 

recent penetration of the abyss by Mesidothea. 

Mesidothea megalura polaris Gurjanova 

Figure 72 F 

Synonym: Mesidothea megalura polaris Gurjanova, 

1946a, pp. 280-281, 295 (English). 


Diagnosis: Mesidothea megalura with clearly pentagonal 

pleon, epimera upturned and body more rugose 

than in subspecies. 

Measurements: 56 mm. 

Type locality: Arctic Ocean, Sedov Station 100, 


one specimen (Gurjanova, op. cit.). 

Distribution: Known only from the Arctic Ocean 

abyss. Not captured by Vema. 

Mesidothea megalura megalura (G. O. Sars) 

Figure 72 G 

Synonyms: Chiridothea megalura G. O. Sars, 1879, 

p. 432; — Ohlin, 1901, p. 24, Figs. 4a-d. Mesidothea 

megalura (G. O. Sars), Hansen, 1916, p. 187. 

Mesidothea megalura megalura (G. O. Sars), Gurjanova, 

1946a. 

Diagnosis: Mesidothea megalura with the epimeral 

plates (coxal plates) not upturned. Body less coarse 

than M. megalura polaris Gurjanova and smaller in size 

Pleon spear point-shaped, not pentagonal. 

Measurements: Female 52 mm. long (Hansen, op. 

cit). 

Type locality: North Atlantic, between Norwayand 

Spitzbergen (Hansen, op. cit., p. 187). 

Distribution: A cold water abyssal species in the 

North Atlantic. It was found by the Ingolj'at Station 


meters, temperature — 1.1 ° C, two specimens; Station 


meters, temperature —1.0° C, four specimens; 


2465 meters, temperature —1.0° C, seven specimens 

(Hansen, op. cit.). Not captured by Vema.

LIST OF ATLANTIC ABYSSAL BIOLOGICAL 

TRAWL SAMPLES OF THE LAMONT 

L.G.O. Biotrawl No. 1, Vema-7-l, 12 November 1955, 

5104-5122 meters, latitude 20° 3.2' N, longitude 68°21.I' 

W., Antilles Outer Ridge, north of the Puerto Rico 

Trench, EBTOG, species of isopods captured: 


Echinothambema ophiuroides Menzies 

Eurycope (Indeterminable) 

Haploniscus unicornis Menzies 

Ianirella vemae Menzies 

Syneurycope hanseni Menzies 

L.G.O. Biotrawl No. 2, Vema-1-2, 1 December 1955, 3425 

meters, latitude 11° 16.6' N., longitude 79° 14.4' W., 

southwestern part of Colombia Abyssal Plain in western 

Caribbean, EBTOC, species of isopods captured: 

No specimens captured. 

L.G.O. Biotrawl No. 5, Theta-l-l, 8 September 1956, 3028 

meters, latitude 27° 05-06' N., longitude 15° 17.9-19.4' 

W., Upper Continental Rise off the coast of Rio de Oro, 

Africa, EBT, species of isopods captured: 


L.G.O. Biotrawl No. 6, Theta-l-3, 11 September 1956, 

4738 meters, latitude 26° 7-28.9' N., longitude 22° 12.0- 

12.2' W., northeast corner Cape Verde Abyssal Plain, 

EBT, species of isopods captured: 


L.G.O. Biotrawl No. 7, Theta-l-4, 23 September 1956, 5779 

meters, latitude 29° 17.6' N., longitude 57° 20.3' W., 

Abyssal Hills between Nares and Sohm Abyssal Plains, 


Abyssijaera ocarina, new species 

Eurycope complanata Bonnier 

L.G.O. Biotrawl No. 8, Theta-l-5, 25 September 1956, 4488 

meters, latitude 31° 30.3-33.5' N., longitude 64° 12.5'-65° 

15.5' W., Bermuda Apron southeast of Bermuda, EBT, 

species of isopods captured: 


L.G.O. Biotrawl No. 9, Tketa-l-6, 26 September 1956, 5166 

meters, latitude 31° 41-43' N., longitude 68° 08' W., 

Bermuda Plateau near western edge of Bermuda Rise, 


Desmosoma birsteini, new species 


Storthyngura vemae, new species 

L.G.O. Biotrawl No. 10, Theta-1-7, 27 September 1956, 

5325 meters, latitude 32° 16.4-21.5' N., longitude 69° 

08.8-13.4'W., Bermuda Rise near northwest boundary, 



L.G.O. Biotrawl No. 11, Theta-l-8, 30 September 1956, 

2238 meters, latitude 38° 33.1-35.7' N., longitude 72° 

32.1-34.4' W., Upper Continental Rise southeast of New 

York, EBT, species of isopods captured: 


L.G.O. Biotrawl No. 12, Vema-\2-\, 6 April 1957, 5024 

meters, latitude 38° 58.5' S., longitude 41° 45' W., 

GEOLOGICAL OBSERVATORY 

northern part of Argentine Rise southeast of Rio Grande 

LBT, species of isopods captured: 


Acanthocope argentinae, new species 


Haplomesus bifurcatus, new species 


Haploniscus minutus, new species 

Haploniscus ovalis, new species 



Haploniscus (Indeterminable) 

Ilyarachna argentinae, new species 

Ischnomesus bidens, new species 

Ischnomesus magnificus, new species 

Ischnomesus paucispinis, new species 

Ischnomesus (Indeterminable) 


Nannoniscoides hirsutus, new species 




Stylomesus spinulosus, new species 

Stylomesus (Indeterminable) 

Xostylus parallelus, new species 

L.G.O. Biotrawl No. 13, Vema-\2-\, 15 April 1957, 4000 

meters, latitude 40° 10' S., longitude 6° 05' W., Eastern 

Steps of Mid-Atlantic Ridge south-east of Tristan da 

Cunha, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 14, Vema-\2-2, 30 April 1957, 3049 

meters, latitude 30° 14.9' S., longitude 13° 03' E., Upper 

Continental Rise southeast of Port Nolloth, Union of 

South Africa, SBT, species of isopods captured: 

Antennuloniscus dimeroceras (Barnard) 

Eurycope ovaloides, new species 




Ilyarachna qfricana, new species 

Ilyarachna triangulata, new species 

Ilyarachna (Indeterminable) 

Ischnomesus decemspinosus, new species 


L.G.O. Biotrawl No. 15, Vema-12-3, 2 May 1957, 4935 

meters, latitude 28° 25.2' S., longitude 8° 28.5' E., 

northern end of Orange Abyssal Plain, SBT, species of 

isopods captured: 

Vemathambema elongata, new species 


meters, latitude 25° 33' S., longitude 12° 27' E., Upper 

Continental Rise off Walvis Bay, South Africa, SBT. 

Species of isopods captured: 

Acanthaspidia bifurcata, new species 

Desmosoma (Indeterminable)


Figure 73. Chart of Lamont Geological Observatory Deep-Sea Biotrawl Stations in the North 

Atlantic. Stations north of 50° N. are Ingolf stations. 




Nannoniscus (Indeterminable) 


L.G.O. Biotrawl No. 17, Vema-\2-b, 4 May 1957, 126 

meters, latitude 24° 18' S., longitude 14° 07.5' E., SBT, 


Desmosoma striata, new species 


meters, latitude 23° 00' S., longitude 08° 11' E., crest of 

Walvis Ridge Front Range west of Walvis Bay, Southwest 

Africa, SBT, species of isopods captured : 

Acanthocope unicornis, new species 

Acanthocope (Indeterminable) 

Desmosoma (Indeterminable) 


Haploniscus spinifer Hansen





Notoxenoides vemae, new species 

L.G.O. Biotrawl No. 19, Fema-12-7, 7 May 1957, 2701 

meters, latitude 22° 58.5' S., longitude 07° 00' E., crest 

of Walvis Ridge west of Walvis Bay, Southwest Africa, 

SBT, species of isopods captured: 



meters, latitude 22° 41' S., longitude 03° 16' E., lower part 

of the western flank of Walvis Ridge, SBT, species of isopods 

captured: 


L.G.O. Biotrawl No. 22, Vema-12-lQ, 21 May 1957, 2997 

meters, latitude 5° 53.5' S., longitude 9° 51.5' E., northern 

wall of Congo Submarine Canyon, Upper Continental 

Rise, SBT, species of isopods captured: 




Leptanthura species 

Macrostylis hirsuticaudis, new species 

L.G.O. Biotrawl No. 23, Vema-\2-U, 23 May 1957, 3921 

meters, latitude 6° 19.3' S., longitude 8° 18.5' E., Congo 

Cone near active canyon on Lower Continental Rise, 






meters, latitude 5° 45' S., longitude 8° 29' E., Lower 

Continental Rise, north edge of Congo Cone, SBT, 



L.G.O. Biotrawl No. 25, 7ema-12-13, 27 May 1957, 4139 

meters, latitude 4° 13.9' S., longitude 0° 18' W., an 

extension of Cameroun trend in Eastern Steps of 

Mid-Atlantic Ridge southwest of Annobon Island, SBT, 



L.G.O. Biotrawl No. 26, Vema-l2-\5, 1 June 1957, 4707 

meters, latitude 1 ° 52' S., longitude 16° 04.5' W., Eastern 

Steps of Mid-Atlantic Ridge northeast of Romanche 

Trench, equatorial Atlantic, SBT, species of isopods 

captured: 


L.G.O. Biotrawl No. 46, Vema-U-22, 6 March 1958, 3705 

meters, latitude ±55° 19' S., longitude ±37° 57' W., 

Archipelagic Apron of Menzies Seamont southwest of 

South Georgia, eastern Scotia Sea, SBT, species of isopods 

captured: 

No specimens captured 

L.G.O. Biotrawl No. 47, Vema-14-23, 6 March 1958, 3756 

meters, latitude 55° 29' S., longitude 37° 57' W., SBT, 

Archipelagic Apron of Menzies Seamount southwest of 

South Georgia, eastern Scotia Sea, species of isopods 

captured: 



Storthyngura (Indeterminable) 

Stylomesus (Indeterminable) 

L.G.O. Biotrawl No. 48, Vema-14-24, 7-8 March 1958, 3473 

meters, latitude 56° 37' S., longitude 34° 48' W., Abyssal 

Hills eastern Scotia Sea southeast of South Georgia 

Island, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 49, Vema-\4-25, 9 March 1958, 2741 

meters, latitude 56° 43' S., longitude 27° 41' W., western 

side of the South Sandwich Island arc between Visokoi 

and Lesokov Islands, SBT, species of isopods captured: 




Serolis (Serolis) macdonnellae, new species 

L.G.O. Biotrawl No. 50, Vema-14-27, 17-18 March 1958, 

3776 meters, latitude 57° 39' S., longitude 13° 32' W., on 

the scarp which marks the boundary between the Lower 

Step and the Middle Step of the Mid-Atlantic Ridge east 

of the South Sandwich Islands, SBT, species of isopods 

captured: 


L.G.O. Biotrawl No. 51, Vema-H-28, 28 March 1958, 4588 

meters, latitude 45° 34' S., longitude 06° 02' E., western 

flank of the Walvis Ridge northwest of Meteor Seamount. 





Haploniscus acutus, new species 

Haploniscus spatulifrons, new species 



Haploniscus tuberculatus, new species 



Ianirella magnifrons, new species 





Stylomesus elegans, new species 

Stylomesus granulosus, new species 

L.G.O. Biotrawl No. 52, Fema-14-29, 30 March 1958, 4960 

meters, latitude 41°03'S., longitude 07° 49'E., southwestern 

flank of the Schmidt-Ott Rise southwest of 

Capetown, SBT, species of isopods captured: 


Antennuloniscus rostratus, new species 

Eurycope acutitelson, new species 



Haploniscus elevatus, new species 


Haploniscus polaris, new species 

Haploniscus telus, new species 

Haploniscus tricornoides, new species 


Ilyarachna multispinosa, new species 

Ilyarachna nodifronoides, new species 






Syneurycope multispina, new species 

L.G.O. Biotrawl No. 53, Vema-H-'il, 4 April 1958, 4885 

meters, latitude 36° 34' S., longitude 14° 08' E., Lower 

Continental Rise southwest of Capetown, SBT, species o: 


Acanthocope annulatus, new species 

Acanthomunna beddardi, new species 

Eurycope nodosa, new species 


Glabroserolis specialis, new species 

Haploniscus bicuspis (G. O. Sars)

Haploniscus nondescriptus, new species 




Ianirella bifida, new species 

Ilyarachna gurjanovae, new species 

Ilyarachna simplex, new species 

Ilyarachna indentifrons, new species 




Macrostylis (Indeterminable) 

Nannoniscus laevis, new species 

Storthyngura symmetrica, new species 



L.G.O. Biotrawl No. 54, Vema-14-32, 6 April 1958, 1816 

meters, latitude 34° 35' S., longitude 17°31'E., SBT, 



Dendromunna spinipes, new species 

Gnathia albescenoides, new species 


Notoxenoides abyssi, new species 



L.G.O. Biotrawl No. 55, Vema-\4-33, 6 April 1958, 706 

meters, latitude 34° 26'S., longitude 17° 32' E., SBT 


Gnathia vemae, new species 

Haploniscus capensis, new species 

Ilyarachna spinoqfricana, new species 

L.G.O. Biotrawl No. 76, Vema-14-48, 9 July 1958, 2526 

meters, latitude 34° 14' N., longitude 24° 10' E., SBT, 



L.G.O. Biotrawl No. 90, Vema-15-5, 4 November 1958, 3378 

meters, latitude 20° 30' N., longitude 73° 16' W., gap 

between Old Bahama Abyssal Plain and Hispaniola- 

Caicos Abyssal Plain, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 91, Vema-15-6, 5 November 1958, 

3897-4080 meters, latitude 19° 26' N., longitude 75° 09' 

W., south scarp of Cayman Trench, south of Guantanamo 

Bay, Cuba, SBT, species of isopods captured: none. 


3094-3076 meters, latitude 15°51'N., longitude 75° 11' 

W., escarpment west of Colombia Abyssal Plain, SBT, 



L.G.O. Biotrawl No. 93, Vema-15-8, 6 November 1958, 3071 

meters, latitude 15° 51' N., longitude 75° 11' W., escarpment 

west of Colombia Abyssal Plain, SBT, species of 




4071 meters, latitude 14° 05' N., longitude 75° 25'W., 

Central part of Colombia Abyssal Plain, SBT, species of 




Heteromesus bifurcatus, new species 



4071 meters, latitude 14° 05' N., longitude 75° 25' W., 

central part of Colombia Abyssal Plain, SBT, species of 





Storthyngura snanoi, new species 

L.G.O. Biotrawl No. 96, Vema-\b-U, 1 November 1958, 

4076, meters, latitude 14° 05' N., longitude 75° 25' W., 

central part of Colombia Abyssal Plain, SBT, species of 




L.G.O. Biotrawl No. 97, Vema-15-12, 8 November 

1958, 2868-2875 meters, latitude 11°30'N., longitude 

75° 50' W., Continental Rise northwest off Cartagena, 

Colombia, SBT, species of isopods captured: 


Nannoniscus primitivus, new species 



W., Continental Rise northwest off Cartagena, Colombia, 




Macrostylis caribbicus, new species 


Mesosignum usheri, new species 

L.G.O. Biotrawl No. 100, Vema-\5-\b, 9 November 1958, 

1714 meters, latitude 10°11'N., longitude 78° 30' W., 



Ischnomesus caribbicus, new species 

Nannoniscus camayae, new species 


1615-1533meters, latitude 10° 11' N., longitude 78°30'W., 





2076 meters, latitude 10°13'N., longitude 78° 33'W., 

Continental Rise north of Colon, Panama, SBT, species 

of isopods captured: 


L.G.O. Biotrawl No. 103, Vema-\5-\8, 10 November 1958, 


W., SBT, species of isopods captured: 

Desmosoma magnispinum, new species 

L.G.O. Biotrawl No. 107, Fema-15-22, 10 November 1958, 

975 meters, latitude 09° 46.3' N., longitude 79° 37.5' W., 



Ischnomesus multispinis, new species 

Nannoniscus (Indeterminable) 

L.G.O. Biotrawl No. 199, Vema-15-115, 14 March 1959, 

3275 meters, latitude 55° 18.2' S., longitude 64° 08.6' W., 

Estados Escarpment south of Staten Island, SBT, species 





Continental Rise south of Staten Island, northwest 

Scotia Sea, SBT, species of isopods captured: 

Ilyarachna scotia, new species 

Scrolls (Serolis) margaretae, new species 


L.G.O. Biotrawl No. 201, Vema-\5-\\7, 15 March 1959, 





Eurycope antarctica Vanhbffen 

Eurycope vicarius Vanhoffen




Munna (Aiunna) argentinae, new species 

Serolis (Serolis) maryannae, new species 


L.G.O. Biotrawl No. 202, Fema-15-118, 16 March 1959, 




Storthyngura birsteini, new species 


3959 meters, latitude 57° 04' S., longitude 61° 25' W., 

Northern Rift Mountains of the Triton Rift System in the 

western Scotia Sea south of Burdwood Bank, SBT, species 





Southern Rift Mountains of the Triton Rift System, 

western Scotia Sea south of Burdwood Bank, SBT, species 




3963 meters, latitude 54° 45.8' S., longitude 52° 02' W., 

Abyssal Hills south of the Scotia Ridge east of Burdwood 

Bank, SBT, species of isopods captured: 



2526 meters, latitude 52" 10.8' S., longitude 49° 04.9' W., 

south side of Falkland Ridge near the north wall of the 

Malvinas Chasm, SBT, species of isopods captured: 



2681 meters, latitude 50° 23.2' S., longitude 47° 25' W., 

central part of Falkland Ridge northeast of the Falkland 

Islands, SBT, species of isopods captured: 

Abyssianira argentenensis, new species 


2738 meters, latitude 49° 35' S., longitude 48° 04.6' W„ 

200 fathoms below the top of the Falkland Escarpment 

northeast of the Falkland Islands, SBT, species of isopods 

captured: 


Stylomesus elegans, new species, 


5042 meters, latitude 49° 21.2' S., longitude 47° 44.6' 

W., lower part of Falkland Escarpment northeast of the 

Falkland Islands, SBT, species of isopods captured: 



6079 meters, latitude 47° 57.5 S., longitude 48° 03' W., 

southern part of Argentine Abyssal Plain, SBT, species of 



L.G.O. Biotrawl No. 211, Vema-\b-\21, 30 March 1959, 

5933 meters, latitude 45° 44' S., longitude 50° 45' W., 

southwest flank of the Argentine Rise southeast of Bahia 

Blanca, Argentine Republic, SBT, species of isopods 

captured : 



5843 meters, latitude 44° 53.3' S., longitude 51 ° 26.5' W., 

southwest flank of the Argentine Rise southeast of Bahia 


captured: 




Nannoniscus oblongus G. O. Sars 

Storthyngura digitata, new species 




5849 meters, latitude 44° 54' S., longitude 51° 35.4' W., 

southwest flank of the argentine Rise southeast of Bahia 


captured: 


L.G.O. Biotrawl No. 214, Fema-15-130, 2 April 1959, 

5293 meters, latitude 42° 00' S., longitude 45° 01.5' W., 

Southwest flank of the Argentine Rise southeast of Bahia 


captured: 


Antarcturus species 



Ischnomesus elegans, new species 

Storthyngura (Indeterminable) 


Stylomesus productus, new species 

Stylomesus simulans, new species 

L.G.O. Biotrawl No. 217, Vema-15-133, 24 April 1959, 

3963-3954 meters, latitude 39° 55.4' S., longitude 42 ; 

38.8' W., north central part of Argentine Rise, SBT, 





L.G.O. Biotrawl No. 218, Vema-15-134, 25 April 1959. 

4166-4144 meters, latitude 27° 53.7' S., longitude 39° 26' 

W., Continental Rise southeast of Rio de Janeiro, SBT. 





Stylomesus regularis, new species 

L.G.O. Biotrawl No. 219, Fema-15-135, 29 April 1959. 

4303-4254 meters, latitude 20° 39' S., longitude 34° 48.5' 

W., Upper Continental Rise east of Valparaiso, South 

America, SBT, species of isopods captured: 


L.G.O.' Biotrawl No. 220, Fema-15-136, 3 May 1959. 

3222-3336 meters, latitude 9° 45' S., longitude 34° 24' W.. 

Continental Rise southeast of Recife, Brazil, SBT, species 




L.G.O. Biotrawl No. 225, Fema-15-141, 10 May 1959. 

4674-4678 meters, latitude 5° 04' N., longitude 41° 01 

W., southeast end of Guiana Abyssal Plain east of thr 

Guianas, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 226, Vema-\5-U2, 14 May 1959, 4932 

meters, latitude 10° 31' N., longitude 45° 02' W., intermontane 

basin floor, western Mid-Atlantic Ridge north 

of the east-west Vema Trough, east of Trinidad, SBT. 



L.G.O. Biotrawl No. 227, Vema-15-143, 25 May 1959. 

3711-3761 meters, latitude 19° 01' N., longitude 65° 39 

W., top of south wall of Puerto Rico Trench north of 

Arecibo, Puerto Rico, SBT, species of isopods captured 


L.G.O. Biotrawl No. 229, Fema-15-145, 1 June 1959. 

5684 meters, latitude 22° 01.5' N., longitude 66° 23.5

W., Antilles Outer Ridge, north of Puerto Rico Trench, 

north of Puerto Rico, SBT, species of isopods captured: 




L.G.O. Biotrawl No. 230, Vema-15-146, 2 June 1959, 


W., Southern part of Nares Abyssal Plain north of the 

Virgin Islands, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 231, Vema-15-147, 4 June 1959, 5440- 

5410 meters, latitude 21° 18.7' N., longitude 65° 13.4' W., 

Antilles Outer Ridge, north of Puerto Rico Trench, north 

of Puerto Rico, SBT, species of isopods captured: 




Haplomesus (Indeterminable), tenuispinis Hansen? 






L.G.O. Biotrawl No. 232, Vema-15-148, 6 June 1959, 5172- 



of Puerto Rico, SBT, species of isopods captured. 




L.G.O. Biotrawl No. 233, Kema-15-149, 7 June 1959, 5291- 







L.G.O.Biotrawl No. 234, Vema-15-150, 11 June 1959, 5477- 

5494 meters, latitude 20° 21.3' N., longitude 66° 24' W., 









Macrostylis setifer, new species 

L.G.O. Biotrawl No. 235, Vema-l5-\5\, 12 June 1959, 6264 

meters, latitude 18° 45.4' N., longitude 66° 30' W., south 

wall of Puerto Rico Trench north of Fajardo, Puerto Rico, 



L.G.O. Biotrawl No. 237, Fem«-15-153, 21 June 1959, 

2370-2357 meters, latitude 25° 01.5' N., longitude 77° 

47' W., floor of the tongue of the ocean west of New 

Provident Island, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 238, Vema-15A5% 21 June 1959, 2668- 


western end of Northeast Providence Channel (Bahamas) 

at the entrance to the tongue of the ocean south of the 

Berry Islands, SBT, species of isopods captured: 


L.G.O. Biotrawl No. 239, Vema-15-155, 22 June 1959, 3727 

meters, latitude 25° 28' N., longitude 77° 15' W., axis of 

Northeast Providence Channel (Bahamas) north of 

Nassau, SBT, species of isopods captured: 



meters, latitude 26° 11' N., longitude 76° 27.5' W., Blake- 

Bahama Abyssal Plain near the mouth of the Northeast 

Providence Channel (Bahamas), SBT, species of isopods 

captured: 


L.G.O. Biotrawl No. 246, Vema-\5-l62, 8 July 1959, 3963- 


Outer Ridge east of the Blake Plateau, SBT, species of 


Macrostylis truncatex, new species 


meters, latitude 32° 34' N., longitude 74° 21.5' W., 

northern end of the Outer Ridge east of the northern part 

of the Blake Plateau southeast of Cape Hatteras, SBT, 


No specimens captured.

LIST OF OTHER ABYSSAL ATLANTIC AND 

ARCTIC STATIONS FROM WHICH 

Albatross Station 2084, North Atlantic, off Georges Bank, 

2361 meters, 40° 16.5' N., 67° 05'15" W., temp. 40° F., 



Albatross Station 2105, North Atlantic, off Virginia, 2557 

meters, 37° 50' N., 73° 03.5' W., temp. 41° F. (Richardson, 

op. cit.), species of isopods captured: 


Albatross Station 2208, North Atlantic, south of Block 

Island, 2155 meters, 39° 33' N., 71° 16'15" W., temp. 

38.4° F., species of isopods captured: 



Albatross Station 2571, North Atlantic, southeast of Georges 

Bank,2480meters,40° 09'30"N., 67° 09' W., temp.37.8°F. 

(Richardson, op. cit.), species of isopods captured: 



Ianirella lobata Richardson 


Bank, 3235 meters, 40° 29.0' N., 66° 04' W., temp. 37.8° F 


Haploniscus excisus Richardson 



Rhacura pulchra Richardson 

Storyngura truncata (Richardson) 


Bank, 3186meters,40°34'18"N.,66° 09'W., temp. 37.3°F. 



Albatross Station 2714, North Atlantic, south of Martha's 

Vineyard, 3337 meters, 38° 22' N., 70° 17'30" W., temp. ? 

(Richardson, 1908a), species of isopods captured: 


Albatross Station 2043, North Atlantic, Cape May to 

Nantucket, 39° 49' 00" N., 68° 28' 30" W., 2680 meters, 

temp. 38.5° F., species of isopods captured: 


Albatross Station 2221, North Atlantic, Cape Hatteras to 

Nantucket, 39° 05' 30" N., 70° 44' 30" W., 2788 meters, 

temp. 36.9° F., species of isopods captured: 

Storthyngura truncata (Richardson) 

Atlantis Station 15, North Atlantic, c. 40° N., 30° E., 



Challenger Station 318, South Atlantic, 3731 meters, 

42° 38' S., 56° 29' W., species of isopods captured: 

Serolis (Serolis) neaera Beddard 

Ingolf Station 18, North Atlantic, south of Denmark Strait, 

latitude 61° 44' N., longitude 30° 29'W., 1135 fathoms 

(2137 meters), temp. 3.0° C. (Hansen, op. cit.), species 


Haplomesus angustus Hansen 

ISOPODS WERE COLLECTED 

Ingolf Station 22, North Atlantic, latitude 58° 10' N., 

longitude 48° 25' W., 3474 meters, temp. 1.4° C. (Hansen, 

op. cit.), species of isopods captured: 




Syneurycope parallela Hansen 

Ingolf Station 24, North Atlantic, Davis Strait, latitude 

63° 06' N., longitude 56° 00' W., 1199 fathoms (2258 

meters), temp. 2.4° C. (Hansen, op. cit), species of isopods 

captured: 


Desmosorna gracilipes Hansen 

Desmosoma intermedium Hult 

Desmosorna simile Hansen 


Eurycope furcata G. O. Sars 

Haplomesus modestus Hansen 



Ianirella laevis Hansen 

Munna {M.) acanthi/era Hansen 

Nannoniscus analis Hansen 

Nannoniscus inermis Hansen 



61°50'N., longitude 56°21'W., 1435 fathoms (2702 

meters), temp. 1.5° C. (Hansen, op. cit.), species of isopods 

captured: 


Desmosoma coarctatum (G. O. Sars) 

Desmosoma gracilipes Hansen 

Desmosoma insigne Hansen 


Eurycope nodifrons Hansen 

Eurycope parva Bonnier 

Haploniscus spinifer Hansen (?), n. sp. ? 



Heteromesus longiremis Hansen 

Ianirella laevis Hansen 

Ilyarachna bicornis Hansen 





60° 17' N., longitude 54° 05'W., 3229 meters, temp. 1.4°C, 



Ingolf Station 38, North Atlantic, south of Davis Strait, 


temp. 1.3° C. (Hansen, op. cit.), species of isopods captured 

: 

Desmosoma longispinum Hansen

20 

200 


60 50 40 30 20 / 10 

•203 .204 

•220 

•219 

v«« 

.49 

40 20 

•26 

J3 

•25 

10 

24 2g 

23? * 

20. 19. 

I* 

Figure 74. Chart of Lamont Geological Observatory Deep-Sea Biotrawl Stations in the 

South Atlantic. 

jo 

•51 

15* 

*2 

I4» 

•53 

20 

10 

50 

60



Hydroniscus abyssi Hansen 


Ischnomesus profundus Hansen 


Nannoniscus armatus Hansen 

Ingolf Station 112, North Atlantic, latitude 67° 57' N., 

longitude 6° 44' W., 2386 meters, temp. —1.1° C, species 



Ingolf Station 113, North Atlantic, south of Jan Mayen, 

latitude 69°31'N., longitude 7° 06' W., 2465 meters, 

temp. —0.1° C. (Hansen, op. cit.), species of isopods 

captured: 

Eurycope hanseni Ohlin 



Gnathia stygia (G. O. Sars) 

Ilyarachna longicomis (G. O. Sars) 


Nannoniscus spinicornis Hansen 

Plankton expedition Station 158, North Atlantic, latitude 

7.5° N., longitude 21.3° W., 4000 meters, species of isopods 

captured: 

Acanthaspidia decorata Hansen 

Porcupine Station 19, North Atlantic, west of Donegal, 

latitude 54° 53' N., longitude 10° 56'W., 2486 meters, 


Thambema amicorum Stebbing 

Sadko Station 10, Arctic Ocean, latitude 80° 02' N., longitude 

3° 19' E., 2380 meters (Gurjanova, 1946a), species of isopods 

captured: 

Eurycope incisa Gurjanova 

Sedov Station 100, Arctic Ocean, latitude 81° 10'N., 

longitude 137° 17' E., 2500 meters (Gurjanova, op. cit. . 


Ilyarachna derjugini Gurjanova 

Mesidothea megalura polaris Gurjanova 

Talisman Station 31, north of San Miguel in the Azores, 22 

August 1883, 2995 meters, species of isopods captured: 

Heteromesus similis Richardson 

Talisman Station 76, North Atlantic, latitude 25° 1' N.. 

longitude 19° 15' W., 2638 meters (Monod, 1926a, 


Gnathia caeca Richardson 

Talisman Station 134, 24 August 1883, 4060 meters, Azores, 


Ilyarachna abyssorum Richardson 

Talisman Station 135, 25 August 1883, 4165 meters, Azores, 


Ilyarachna abyssorum Richardson 

Talisman Station 139, coast of Soudan between Dakar and 

Praya, 3200 meters (Richardson, 1911), species of isopods 

captured: 


Thor Station, North Atlantic, south of Iceland, latitude 

60° 11' N., longitude 19° 36' W., 1899 to 2143 meters 

(Hansen, op. cit.), species of isopods captured: 

Ianira hanseni, new species 

Munna (Munna) acanthifera Hansen 

Valorous Station 8, North Atlantic, near entrance of Davis 


meters, species of isopods captured: 

Ananthura abyssorum (Norman and Stebbing) 

Valorous Station 11, North Atlantic, latitude 56° 11' N., 

longitude 37° 41' W., 2651 meters, species of isopods 

captured: 

Hyssura producta Norman and Stebbing

Barnard, K. H. 1920. Contributions to the crustacean 

fauna of South Africa. No. 6. Further additions to the 

list of Marine Isopoda. Ann. So. African Mus. 1 7. part 

V, no. 11, pp. 319-438, pis. XV-XVII. 

1925. A revision of the family Anthuridae (Crustacea, 

Isopoda), with remarks on certain morphological 

peculiarities. Linnean Soc, Jour. (Zool.) 36: 109-160. 

Beddard, F. E. 1884. Preliminary notice of the Isopoda 

collected during the voyage of H.M.S. "Challenger." Part 

I. Serolis Proc. Zool. Soc. London. Mav, 1884, pp. 330- 

341. 

1886. Preliminary notice of the Isopoda collected 

during the voyage of H.M.S. "Challenger." Part II. 

Munnopsidae. Proc. Zool. Soc. London, December, 1885, 

pp. 916-925. 

1886a. Preliminary notice of the Isopoda collected 

during the voyage of H.M.S. "Challenger." Part III. 

Proc. Zool. Soc. London, No. 7, pp. 97-122. 

1886 b. Report on the Isopoda collected by H.M.S. 

"Challenger" during the years 1873-76, part 2, 

"Challenger" Reports, Zoology, vol. 17, 175 pp., 25 pis. 

Birstein, J. A. 1957. Certain peculiarities of the ultra-abyssal 

fauna at the example of the genus Storthyngura 

(Crustacea Isopoda Asellota). Akad. Nauk. SSSR. 

36 (7): 961-985 (summary in English). 

1960. The family Ischnomesidae (Crustacea, Isopoda, 

Asellota) in the north-western part of the Pacific and 

the problem of amphiboreal and bipolar distribution 

of the deep sea fauna. Zool. Zhurnal SSSR. 39 (1:) 

3-28 (summary in English). 

1961. Microthambema tenuis n. gen., n. sp. (Isopoda, 

Asellota) and relations of some asellote isopods. Crustaceana2 

(2): 132-141. 

Bonnier, J. 1896. Edriophthalmes, in Resultats Scientifiques 

Campagne "Caudan" dans le Golfe de Gascogne. 

Ann. Univ. Lyon 26: 527-689. Paris. 

Dollfus, A. 1901. Etude preliminaire des Gnathiidae 

recueillis dans les camp, de l'Hirondelle et de la Princesse 

Alice. Bull. Soc. Zool. France 26: 239-246. 

Fabricius, J. C. 1775. Systema entomolologiae (not seen 

by writer). 

Gurjanova, E. 1933. Contributions to the Isopod Fauna of 

the Pacific Ocean. II. New Species of Gnathiidea and 

Asellota, pp. 79-88 (Russian), 89-91 (English). Expl. 

Mers U.S.S.R. Leningrad, no. 19. 

1946a. New Species of Isopoda and Amphipoda from 

the Arctic Ocean. Vol. 3. Compendium of Results of 

Drifting Expedition of Ice-Breaker "Cedov" 1937-1940 

(English summary). Chief Office of Northroad, Moscow. 

1946b. Individual and age variability of the marine 

assel and its importance in evolution of the genus 

Mesidothea Rich. Trav. Inst. Zool. Acad. Sci. URSS 

8: 105-144. 

Hansen, H. J. 1895. Isopoden, Cumaceen u. Stomatopoden 

der Plankton-Expedition. Erg. Plankt. Exp. Humb. 

Stft. 2, 4 (3), pp. 1-105. 

1897. Reports on thedredgingsof the Albatross, XXII. 

Isopoda. Bull. Mus. Comp. Zool., Harvard 31: 95-129. 

1916. Crustacea Malacostraca III (V). The Order 

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The Isopods of Abyssal Depths in the Atlantic Ocean

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