Cystisoma pellucida

Zeidler, Wolfgang, 2003, A review of the hyperiidean amphipod family Cystisomatidae Willemöes­Suhm, 1875 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 141, pp. 1-43 : 9-14

Cystisoma pellucida (Willemöes ­Suhm) ( Figs 1­3 )

Thaumops pellucida Willemöes­Suhm, 1873: 207 ­208. – Willemöes­Suhm, 1874a: 182. Willemöes­Suhm 1874b: 629 ­635, pl. 49, 50.

Cystosoma pellucida – Kingsley 1884: 73 ­74, fig. 99.

Thaumatops pellucida – Bovallius 1886: 8 ­10. Bovallius 1887a: 14. Woltereck 1903: 452 ­454, fig. 1. Stephensen 1918: 64 ­66, figs 19, 24­27. Schellenberg 1927: 622, fig. 31. Spandl 1927: 172 ­ 173, fig. 10.

Cystisoma pellucidum – Barnard 1932: 272 (spec. 1 & 6). Pirlot 1938: 364 ­365. Thorsteinson 1941: 92 ­93. Hurley 1956: 10. Brusca 1967a: 387. Brusca 1967b: 451. Brusca 1973: 14. Brusca 1981a: 19 (key), 39, fig. 5b. Brusca 1981b: 358.

Cystisoma pellucida – Vinogradov et al. 1982: 246 ­248, fig. 121. Zeidler 1992: 96, fig. 9. Vinogradov 1999: 1177, fig. 4.74.

Cystisoma spinosum [misidentification] – Stebbing 1888: 1325 ­1329, pl. 155 (spec. B).

Thaumatops spinosa [misidentification] – Vosseler 1901: 94. Woltereck 1903: 449 ­450, 453 (key).

Type material

The unique type, an ovigerous female measuring 84 mm, could not be found in the BMNH and is presumed lost. Fortunately the description and figures given by Willemöes­ Suhm (1874b) are clearly of C. pellucida as understood by modern taxonomists. As the characteristic features of this species are very distinctive its status is not in doubt, despite the loss of the type. The type locality is off Cape St. Vincent, 35º47’N, 8º23’W, in a trawl from 1090 fathoms.

Material examined (54 specimens)

North Atlantic: 3 lots ( BMNH), 5 lots ( ZMUC), 9 specimens. North Indian: 1 lot ( ZMUC), 1 specimen. South Indian: 10 lots ( ZMUC), 11 specimens. Central Indo­ Pacific: 2 lots ( USNM), 13 lots ( ZMUC), 21 specimens. South Pacific: 6 lots ( ZMUC), 6 specimens. Tasman Sea: l lot (AM), 3 lots ( ZMUC), 4 specimens. Great Australian Bight: 1 lot ( SAMA), 1 lot ( ZMUC), 2 specimens.

Diagnosis (female only)

Body length up to 85 mm. Head about as long as deep; almost as long as first six pereonites combined; oval when viewed laterally, with slightly convex anterior margin when viewed dorsally. Marginal spines, 10­15; anterior ventral spine larger than glandular spine, clearly the largest; oral spines, 3­5 in arched row. Eyes oval, barely separated medially. First antennae subequal in length to head, ending with swollen gland, with one or two tiny terminal articles. Mandibles with only one medial tooth. Pereopod 5 & 6; carpus distinctly shorter than propodus. Urosome (with uropods) slightly longer than pleon. Uropod 1; exopod length twice length endopod, and about half­length of peduncle, slightly swollen terminally with gland. Uropod 3 similar to U1, but exopod length about 0.6x length of peduncle.

Male unknown (see remarks)

Remarks

There has been some confusion regarding the correct citation of this species (e.g. Vinogradov et al. 1982). Willemöes­Suhm’s description of this species was received by the Royal Society of London on 27th February, 1873. An abbreviated version was published in the Societies’ Proceedings in 1873 and a more detailed description with figures in the Transactions in 1874. Thus, the correct citation for this species is Willemöes­Suhm, 1873.

This is one of the most distinctive species of Cystisoma , readily distinguished by the characteristic shape of the first antennae and the exopods of the uropods, because of the presence of a swollen gland. The distal part of the propodus of pereopods 3­7 is also slightly swollen, because of the presence of a gland, but this is not always very obvious, except for pereopod 7 of mature females, in which the propodus becomes considerably swollen terminally, a feature also found in all other species of Cystisoma .

Males of this species could not be determined in any of the collections examined. Willemöes­Suhm (1874b), Pirlot (1938) and Brusca (1967b) refer to males of C. pellucida but do not provide any information as to how they differ from females, if at all! These authors may have mistaken immature females for males, or made an error in identification. However, Vinogradov et al. (1982) also refer to males, and provide some information on sexual differences. They mention that the head of males is relatively lower, the antennae are much longer than the head and the exopod of U1 is only slightly longer than the endopod. Unfortunately this material was not available for study.

Figures

FIGURE 1. Cystisoma pellucida, Great Australian Bight, SAMA C 5541. Female, 75 mm. A, lateral view; B, dorsal view of head. Scale bars = 10.0 mm (A, B), 0.2 mm (Md, Mx 1 & 2).

FIGURE 2. Cystisoma pellucida, Great Australian Bight, SAMA C 5541. Female, 75 mm. Scale bars = 5.0 mm.

FIGURE 3. Cystisoma pellucida, Great Australian Bight, SAMA C 5541. Female, 75 mm. A, oral spines; B, buccal mass; C, second brood plate, medial view; D, second brood plates, ventral view; E, first brood plates, ventral view. Scale bars = 2.0 mm (C­E), 1.0 mm (A, B), 0.5 mm (remainder).