Psolidium ravum Hickman, 1962

O’Loughlin, P. Mark & Ahearn, Cynthia, 2008, Australian species of Psolidium Ludwig (Echinodermata: Holothuroidea: Psolidae), Memoirs of Museum Victoria 65, pp. 1-22 : 17-18

Psolidium ravum Hickman

Table 1 , Figures 1e , 8d–e

Psolidium ravum Hickman, 1962: 60-61 , figs 75–86, pl. 2 fig. 7.— Dartnall, 1980: 51, 77.— Rowe, 1982: 458, 464, fig. 10.29c.—Rowe (in Rowe and Gates), 1995: 318–19.

Material examined. Syntype: SE Tasmania, Derwent Estuary, Ralphs Bay , dredged, 13 m, 28 Aug 1959, AM J7202 (1).

Other material: N point of Trial Bay, near Kettering, 3 m, under rock, 31 Mar 1991, SAM K2180 (1) ; Hobart , AM G248 (3) ; Frederick Henry Bay, Primrose Sands, Renard Point , under rock, 3–4 m, K. L. Gowlett Holmes, 25 Aug 1999, K2178 (1) ; Bass Strait, Lulworth , Black Rock Point, M. O’Loughlin et al., 22 Nov 1982, NMV F97439 (1) ; Tamar R., Greens Beach, M. O’Loughlin, 7 Mar 1981, NMV F97440 (1) . Victoria, Bass Strait, Ninety Mile Beach , 10 km W of Seaspray, J. Watson, 1977, AM J11171 (1) ; Portland, 500 m E of Whalers Point Lighthouse , 10 m, under rocks, P. Berents and R. Springthorpe, 10 May 1988, AM J21980 (1) ; Saxon Reef , 10 m, J. Watson, 24 Feb 2007, NMV F125379 (1) . South Australia, Spencer Gulf, Yorke Peninsula, Port Elizabeth , 7 m, K. Sheard, 23 Feb 1941, SAM K2182 (1) ; Pt Turton jetty , 3–4 m, N. Holmes, 31 Aug 1986, SAM K2186 (1) ; W Eyre Peninsula, Streaky Bay, Pt Westall, littoral , M. O’Loughlin, 15 Jan 1991, NMV F97438 (1) ; Nuyts Archipelago, Franklin I , 12–15 m, W. Zeidler and P. Aerfeldt, 23 Feb 1983, SAM K2183 (1).

Description. Psolidium species up to 40 mm long (preserved); body form oval to elongate; body height low to moderately high; dorsal and lateral scales thick, up to 2 mm wide, covered with thick integument; dorsal and lateral tube feet conspicuous, numerous.

Sole: peripheral band of tube feet, 4-5 wide, not always continuous anteriorly and posteriorly, lacking series of distinctly separate outer small tube feet; regular, close series of mid-ventral radial tube feet, 2 wide.

Dorsal and lateral ossicles: multi-layered perforated ossicles (scales), thick, irregular form; deeply cupped crosses with distal spinous to digitiform spinelets, rare partially or fully closed cups, 32–72 μ m long, typical size range 40–56 μ m long; small to large buttons, up to 12 perforations, thick, smooth, irregular form, up to 216 μ m long, intergrade with multi-layered ossicles.

Ventral ossicles: predominantly large single-layered perforated plates, up to 16 perforations, rarely up to 38 perforations in larger specimens, variable thickening, irregularly round to elongate, smooth, irregular margin, up to 360 μ m long; perforated plates with variable surface and peripheral knobs rare; perforated plates with 4 perforations rare; moderately deep to deeply cupped crosses with distal spinous to knobbed spinelets, rare partially or fully closed cups, typical size range 40–48 μ m long, rarely up to 56 μ m long.

Tentacle ossicles include rosettes, irregularly oval, densely branched, up to 96 μ m long in larger specimens.

Colour. Live: grey dorsally and laterally. Preserved: dark brownish-grey to off-white dorsally and laterally; sole brown to grey-brown.

Distribution. SE Tasmania (Derwent Estuary), Bass Strait, to W South Australia (Nuyts Archipelago); 0– 15 m.

Remarks. Although not reported by Hickman (1962), the syntype and all of the specimens determined here to be P. ravum have rosettes in the tentacles. The specimen from the Eyre Peninsula ( NMV F97438 ) ventrally has more abundant plates with 4 perforations, but the external morphology and presence of cupped crosses dorsally and ventrally are typical of P. ravum . The specimens from Frederick Henry Bay ( SAM K2178) and Kettering (K2180) have similar morphological appearances to P. laperousazi sp. nov., but the dorsal and ventral ossicles are typical of P. ravum . Knobbed to spinous plate margins in the sole of the specimens from Port Elizabeth ( SAM K2182) and Portland ( NMV F125379) are similar to those of P. karenae sp. nov. and P. granuliferum H. L. Clark , but the external morphology and presence of dorsal and ventral cupped crosses and cups are typical of P. ravum . Small ossicles were absent from specimens from Nuyts Archipelago ( SAM K2183) and Yorke Peninsula (K2186) (probably formalin preservation history), but the specimens have the typical external morphology of P. ravum . The distinguishing characteristics of Psolidium ravum Hickman, 1962 are the conspicuous dorsal and lateral tube feet, the predominance of cupped crosses over cups dorsally and ventrally, large rosettes in the tentacles, and absence of dark spots on the sole.

Figures

Figure 1. Photos of live specimens of Psolidium Ludwig, 1886 (a–d, in situ by K.Gowlett-Holmes; e, in aquarium by L.Altoff):a, P. granuliferum H. L. Clark, 1938, Port Davey, Tasmania (14 mm long preserved; SAM K2174, PK0259); b, P. karenae sp. nov., Yorke Peninsula, South Australia (17 mm long preserved; holotype SAM K2177, PK0105); c, P. laperousazi sp. nov., Kangaroo I, South Australia (13 mm long preserved; paratype SAM K2179, PK0253); d, P. marshae sp. nov., Kangaroo I (10 mm long preserved; SAM K2173, PK0273); e, P. ravum Hickman, 1962, Portland, Victoria (17 mm long preserved; NMV F125379).

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).