Psolidium schnabelae O'Loughlin & Ahearn 2008, sp. nov.

Psolidium schnabelae sp. nov.

Figures 3a; 8 a-c

Material examined. Holotype: Eastern Antarctica, MacRobertson Land, slope off Prydz Bay, BANZARE stn 29, 66°28’S 72°41’E, 1266 m, 25 Dec 1929, SAM K2345.

Other material: type locality and date, SAM K2346 (2).

Diagnosis. Psolidium species up to 25 mm long; body form elongate, high; dorsal and lateral scales conspicuous, thin, smooth, up to 2.5 mm wide; dorsal and lateral tube feet 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: multi-layered perforated plates (scales), single-layered marginally, reticulate thickenings extend from margin towards centre of plate, multi-layered centrally, lacking frequent radiating linear thickenings between marginal perforations, lacking smooth white thickening with small perforations, margin with irregular thickenings and perforations, not smooth; up to 4 tube foot canals or marginal indentations per plate; small mesh-like tube foot endplates, about 5 perforations, 40 μ m wide; lacking dorsal and lateral tube foot support plates.

Sole ossicles: throughout sole rare, small, smooth, thin, irregularly shaped rods and perforated plates, up to 10 perforations, up to 240 μ m long, sometimes as regular 4-holed plates with bluntly spined margin, sometimes surface knobs, up to 180 μ m long; near margin of sole and peripheral tube feet thicker irregular rod-plates and very thick irregular perforated plates, up to 300 μ m long.

Tentacles: largest tentacle trunk ossicles predominantly smooth perforated plates, irregularly oval, large central perforations grading to numerous small close ones near margin, finely denticulate margin, plates up to 520 μ m long; some thicker plates with large perforations, plates up to 300 μ m long; few rod-plates, up to 300 μ m long.

Colour (preserved). Body pale brown to off-white; scales haloed, with pale outer edge (single-layer perforated edge of scales with white thickening).

Distribution. Eastern Antarctica, MacRobertson Land, slope off Prydz Bay; 1266 m.

Etymology. Named for Kareen Schnabel (NIWA), with gratitude for her generous and gracious assistance with loan material and data from NIWA.

Remarks. The original BANZARE lot from station 29 comprises three specimens. We are not confident that the two smaller specimens are conspecific with the holotype, and they are assigned to “Other material” with reservation. We note that this species is recorded for a significantly greater depth than the other species of the Psolidium poriferum group. Psolidium schnabelae sp. nov. is distinguished diagnostically by the predominant form of the largest tentacle ossicles with large central perforations grading to small peripheral ones.