The Isopods of Abyssal Depths in the Atlantic Ocean

Measurements: Holotype male length 3.4 mm.,
width pleon 1.0 mm., allotype length 3.2 mm., width
pleon 0.9 mm.
Type locality: South Atlantic, L.G.O. Biotrawl No.
52, types plus six male and six female paratypes, cat.
no. 1-138.
Distribution: Known only from type locality.
Affinities: This species is unique in its sharp
pleonal antero-lateral borders.
Eurycope nodosa, new species
Figure 36 F-H
Synonyms: None.
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.
Measurements: Female holotype length 4.6 mm.,
width pleon 1.4 mm.
Type locality: South Atlantic, L.G.O. Biotrawl No.
53, type and one female paratype, cat. no. 1-137.
Distribution: Known only from type locality.
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
Synonyms: None.
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
mm., width pleon 1.9 mm.
Type locality: South Atlantic, L.G.O. Biotrawl No.
14, type and one female paratype, cat. no. 1-127.
Distribution: Known only from type locality.
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
ABYSSAL ATLANTIC ISOPODS 145
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;
— Hansen, 1916, p. 132; — Wolff, 1956, p. 112.
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)
Depth Range {Meters)
Least Greatest
3423
2490
2012
2258
2788
2305
5230
5850
1256
6475
7246
7210
5670
5345
6156
7305
400
A KEY TO THE SPECIES OF
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