Psolidium emilyae, O’Loughlin & Ahearn, 2008

O’Loughlin, P. Mark & Ahearn, Cynthia, 2008, Antarctic and Sub-Antarctic species of Psolidium Ludwig (Echinodermata: Holothuroidea: Psolidae), Memoirs of Museum Victoria 65, pp. 23-42 : 30

Psolidium emilyae sp. nov.

Figures 1d; 4 c-e

Material examined. Holotype: Eastern Antarctica, Prydz Bay , Four Ladies Bank, ANARE 1991, Aurora Australis stn 25B, 68°31’S 77°27’E, 450-556 m, K. L. Gowlett-Holmes and W. Zeidler, 3 Feb 1991, SAM K2221.

Diagnosis. Psolidium species 14 mm long (preserved); elongate tubular body, transversely rounded form, sole narrower than body width; dorsal and lateral tube feet conspicuous, numerous, cover body closely; dorsal and lateral scales inconspicuous.

Sole: peripheral single series of tube feet; some slightly smalleroutertubefeetinanincompleteseries(partlyconcealed by projecting ventro-lateral scales); lacking mid-ventral (sole) radial series of tube feet.

Dorsal ossicles: thick, smooth, single-layered perforated plates (scales), lacking secondary developments, small perforations, tube foot canals, scales up to 0.7 mm wide; irregular,curvedtubefootsupportossicles,upto4perforations, up 128 μ m long.

Sole ossicles: numerous crosses, predominantly regular, elongate, 4-armed, thick, with distal pairs of swellings on arms, branches rarely joined to create perforations, up to 144 μ m long; few thick perforated plates, up to 10 perforations, margin variably bluntly toothed to slightly knobbed, up to 224 μ m long.

Colour (preserved). Off-white.

Distribution. Eastern Antarctica, Prydz Bay, Four Ladies Bank; 450– 556 m.

Etymology. Named for Emily Whitfield (Marine Research Group of the Field Naturalists Club of Victoria) who first noticed the distinctive cross ossicles in the sole of this species, and in appreciation of her research assistance in Museum Victoria.

Remarks. The cross ossicles in the sole of Psolidium emilyae sp. nov. are diagnostically distinctive among Antarctic and Sub-Antarctic Psolidium species, and tentacle ossicles from the unique small holotype specimen were not examined. P. emilyae is similar morphologically to Psoldium normani sp. nov. from Prydz Bay (see below), but the depth of occurrence of P. normani (105–193 m) is shallower than P. emilyae (450–556 m). A single specimen from Prydz Bay (98–301 m) of the morphologically similar Psolidium gaini Vaney, 1914 , also occurred at a shallower depth than P. emilyae . Ossicles from the sole of specimens of P. gaini and P. normani that were similar in size to the small type specimen of P. emilyae were examined, and found to be similar to those in larger specimens of the two species, and not the crosses typical of P. emilyae .