Psolidium gaini Vaney 1914

Psolidium gaini Vaney

Figures 1e; 5 a-c; 6a, b

Psolidium gaini Vaney, 1914: 18–20, pl. 1 figs 7–9, pl. 4 figs 6–14.— Ekman, 1925: 5, 117–19, text-fig. 28.— Ekman, 1927: 414–15.— Grieg, 1929a: 13.— Grieg, 1929b: 9.— Pawson, 1969: 38, map 3.— Arnaud 1974: 651.— Cherbonnier, 1974: 608.— Gutt, 1988: 23, 28, 30, 32, 65, 73, 77.— Gutt, 1991a: 147, 149, 152, 153.— Gutt, 1991 b: 324.

Psolidium sp. MoV 2081.— O’Loughlin et al., 1994: 552, 554.

Material examined. Antarctic Ocean, South Orkney Is, 298–302 m, USNM E40558 (1 specimen); South Shetland Is, Aspland I., 163–180 m, AMLR-03 stn 90, 20 Mar 2003, NMV F104812 (2); Antarctic Peninsula, Joinville I., 210–220 m, USNM E40559 (10); Graham Land, 91 m, E40561 (2); Palmer Archipelago, 85–130 m, E40552 (2); 102 m, E40553 (1); 38–70 m, E40554 (2); 70–150 m, E40555 (2); 55 m, E40562 (1).

Ross Sea, Terra Nova stn 340, 76°56’S 164°12’E, 293 m, BM(NH) 1932.8.11.253 (2); NZOI Endeavour stns A461, 0–550 m, NIWA 43882 (1); A 534, 366 m, NIWA 43884 (2); A 537, 546 m, NIWA 43885 (1); E209B, 163 m, NIWA 43886 (2); Discovery stn 1660, Pennell Bank, 0–351 m, BM(NH) 2008.3183-3189 (7); Tangaroa stn 0802/ 100, 451–447 m, NIWA 45696 (4).

Victoria Land, 640–646 m, USNM E40556 (2); 598–613 m, E40560 (1); 573–576 m, USNM 1082084 (1); 598–613 m, USNM 1112624 (1); Balleny Is, 55-146 m, E40551 (19); 150–157 m, E40557 (1); Tangaroa stn 0602, 140–150 m, NIWA 44712 (1).

Adelie Land, BANZARE stn 90, 66°21’S 138°28’E, 640 m, SAM K2340 (1).

Prydz Bay, Four Ladies Bank, 298–301 m, NMV F68112 (1).

Diagnosis. Psolidium species up to 27 mm long (up to 40 mm in Vaney, 1914); body elongate, transversely rounded form (preserved), sole narrower than body width; dorsal and lateral tube feet conspicuous, numerous, cover body closely; dorsal and lateral scales inconspicuous.

Sole: outer peripheral single series of smaller tube feet; inner peripheral single series of larger tube feet; lacking mid-ventral (sole) radial series of tube feet.

Dorsal ossicles: thick, smooth to irregularly thickened, single-layered, perforated plates (scales), up to 950 μ m long, perforations small, up to 3 canals or marginal indentations for tube feet per scale; irregular, asymmetrical, curved tube foot support plates, 4–8 perforations, digitiform to bluntly spinous (South Shetland Is) to pointed spines (Prydz Bay) on one margin, opposite margin lacking projections, plates up to 176 μ m long.

Sole ossicles: thick, regular, 4-holed buttons, variably knobbed to bluntly spinous marginally, 160–190 μ m long; intergrade with thick, smooth, perforated plates, sometimes slightly concave, sometimes slightly knobbed marginally, sometimes margin upturned, number of perforations variable, size of plates variable; plates up to 14 perforations, up to 184 μ m long, many knobbed marginally (South Shetland Is); plates up to 19 perforations, up to 255 μ m long (Ross Sea); plates up to 17 perforations, up to 224 (rarely 272) μ m long, slight swellings marginally (Prydz Bay).

Distribution. South Georgia, South Orkney Is, South Shetland Is, Weddell Sea, Antarctic Peninsula to Ross Sea to Prydz Bay; 19– 795 m.

Remarks. Vaney (1914) reported the sizes of the two type specimens as 40 and 30 mm long. It is incongruous that none of the numerous specimens seen in this study is longer than 26 mm. Ekman (1925) noted some differences between the specimen that he examined and the description by Vaney (1914), and made a point that what Vaney described as “cups” dorsally, were for him tube foot support ossicles. We agree with Ekman (1925) that there are numerous tube foot support ossicles dorsally, that have the form of irregular curved perforated plates that are superficially cup-like. The dorsal and lateral tube feet in Psolidum gaini, P. emilyae sp. nov. (above) and P. normani sp. nov. (below) are conspicuous because of the presence of support ossicles, whereas the dorsal and lateral tube feet of Psolidium poriferum (below), P. pawsoni sp. nov. (below), P. schnabelae sp. nov. (below), P. tenue (below) and P. whittakeri sp. nov. (below) have at most rare tube foot support ossicles and are inconspicuous.

We noted plates from the sole of Antarctic Peninsula specimens (type region) up to 200 μ m long with up to 13 perforations. Sole plates from Adelie Land specimens were up to 300 μ m long with up to 23 perforations. Other variations are noted in the diagnosis above. The variations are significant, and suggest that there may be more than one species.

Grieg (1929a, b) reported Psolidium gaini from South Georgia (55 m) and Graham Land (60–90 m), and noted reports of P. gaini from the South Shetland Is (19 m) and Emperor William Land (360 m). Gutt (1988) reported P. gaini from the Weddell Sea (260–795 m).