Psolidium parmatus (Sluiter)

O’Loughlin, P. Mark & Ahearn, Cynthia, 2008, Australian species of Psolidium Ludwig (Echinodermata: Holothuroidea: Psolidae), Memoirs of Museum Victoria 65, pp. 1-22 : 17

Psolidium parmatus (Sluiter)

Table 1 , Figures 3e–f , 8a–c

Psolus parmatus Sluiter, 1901: 102 –03, pl. 6 fig. 14.

Material examined. Holotype (very poor condition): Indonesia, Banda Sea , Siboga stn 259, 5°29.2'S 132°52.5'E, coral sand, 487 m, V.ECH. H1300.

Other material. Western Australia, Ningaloo North, Southern Surveyor SS 2005/10 stn 163, 21.94°S 113.84°E, hard substrate, 133 m, 12 Dec 2005, NMV F112156 (1) ; Adele, SS05/2007 stn 161, 14.5622°S 122.9182°E, hard rubble, 95 m, 4 Jul 2007, F151835 (1); Kulumburu, SS05/2007 stn 176, 13.2247°S 123.3957°E, 400 m, F151836 (1).

Arafura Sea, Southern Surveyor SS 05/2005 stn 42, 9°7.018'S 133°24.725'E, 204 m, 18 May 2005 , F109377 (1); SS05/2005 stn 43, 9°5.312'S 133°2.989'E, 226 m, 19 May 2005, F109378 (1).

Description. Psolidium species up to 13 mm long (preserved); dorsal and lateral scales up to 2.0 mm wide, scales each with numerous blunt calcareous vertical projections; dorsal and lateral tube feet not conspicuous amongst projections.

Sole with peripheral band of tube feet, single outer series of smaller tube feet, inner single series of larger ones; lacking mid-ventral radial series of tube feet.

Dorsal and lateral ossicles: single to multi-layered perforated plates (scales), lace-like secondary surface developments to multi-layering, tube foot canals; each scale with numerous thick, bulbous calcareous spires, constricted basally, rounded distally, about 200 μ m high, 136 μ m widest diameter, finely spinous surface; irregular branched pointed rod “thorn” ossicles, up to 160 μ m long; shallow concave cups, perforations large, typically 4 around central cross, frequently 4 smaller corner perforations, cups knobbed around margin and on cross, cups typically 120 μ m long; lacking rosettes.

Sole ossicles: shallow concave cups, perforations large, typically 4 around central cross, frequently 4 smaller corner perforations, cups knobbed around margin and on cross, cups typically 112 μ m long; “thorn” ossicles up to 96 μ m long; lacking rosettes.

Colour (preserved). White dorsally, laterally, ventrally.

Distribution. Indonesia (Banda Sea), Arafura Sea, to NW Western Australia (Ningaloo North); 95– 487 m.

Remarks. Tube feet pass through the dorsal and lateral scales of Psolus parmatus Sluiter, 1901 . The species is re-assigned here to Psolidium Ludwig. The distinctive species characteristic of Psolidium parmatus (Sluiter) is the presence of numerous blunt vertical calcareous projections on each of the dorsal and lateral scales. These projections resemble “shields” in profile, and hence the species name chosen by Sluiter (parma, Latin for “small shield”).

Figures

Figure 3. Photos of preserved specimens of Psolidium Ludwig, 1886 (by L. Altoff): a, P. marshae sp. nov., Geographe Bay, Western Australia (dorsal view; 8 mm long; holotype WAM Z31173); b, P. mccallumae sp. nov., slope off Point Cloates, Western Australia (lateral view; 7 mm long; holotype NMV F126891); c–d, P. nigrescens H. L. Clark, 1938, Gunnamatta Bay, New South Wales (40 mm long; AM J6821); c, lateral view; d, ventral view (sole); e–f, P. parmatus (Sluiter, 1901), Adele slope, Western Australia (9 mm long; NMV F151835); e, lateral view; f, ventral view (sole).

Figure 8. Photos of ossicles from Australian species of Psolidium Ludwig, 1886 (by Mark O’Loughlin and Chris Rowley): a–c, P. parmatus (Sluiter, 1901); a, dorsal scale with tube foot canal (holotype V.ECH.H1300); b, pillars on edge of part of scale (NMV F109378); c, dorsal “thorns” (holotype V.ECH.H1300); d–e, P. ravum Hickman, 1962 (SAM K2180); d, dorsal cupped crosses; e, cupped cross and plate from sole; f, P. spinuliferus (H. L. Clark, 1938), tentacle rods and dendritic branch endplates (top right) (AM J24096).