Psolidium spinuliferus (H. L. Clark)

Table 1, Figures 4a, 8f, 9a–d

Psolus spinuliferus H. L. Clark, 1938: 509–11, fig. 53.—H. L. Clark, 1946: 414.— Cannon and Silver, 1987: 29.—Rowe (in Rowe and Gates), 1995: 319.

Material examined. Northern Territory, Darwin Harbour, North Shell I, 12°29'48"S 130°53'12"E, coral rubble covered with sponges and some algae, 5 m, P.A.Hutchings, 16 Jul 1993, stn NT 346, AM J24096 (1) . Western Australia, Perth, Cottesloe, Mudurup Rocks, c 70 m S of groyne, reef flat, Sargassum zone, on reef flat under thin veneer of sand, 31°59'51"S 115°45'01"E, 0–1 m, J. Keesing, 6 Feb 2007, WAM Z37479 (1); Trigg I, c 100 m N of ‘island', inshore mixed algal zone mid-platform with thin veneer of sand overlaying reef, 31°52'29"S 115°45'04"E, 0–1 m, J. Keesing, 19 Feb 2007, Z37478 (1); Waterman, Sargassum zone, mid-platform, 31°51'15"S 115°45'05"E, 0–1 m, J. Keesing, 14 Feb 2007, Z37468 (5); from mixed localities, Cottesloe and Trigg I, inter-tidal platforms, on reef flat under thin veneer of sand, J. Keesing, Feb 2007, Z37469 (1) .

Description. Psolidium species up to 20 mm long (preserved); dorsal and lateral body scales thin, single-layered, with spires, scales up to 1.5 mm wide; tube feet dorsally and laterally pass through scales, not conspicuous amongst spires.

Sole: peripheral band of tube feet, outer single series of smaller tube feet, inner single to zig-zag series; mid-ventral radial series irregular, double to zig-zag to scattered.

Dorsal and lateral ossicles: single-layered, thick, perforated plates (scales), irregularly oval, some with secondary thickening, most with vertical digitiform spire near margin; spires up to 400 μ m long, 120 μ m diameter, distally spinous.

Sole ossicles: knobbed plates, numerous, predominantly regular 4-holed thin plates, smooth to finely knobbed marginally, typically 80 μ m long; lacking cupped crosses, cups, rosettes.

Tentacle ossicles include: thick perforated plates, elongate, variable form, some with secondary layer development, up to 352 μ m long; numerous rosettes, large to small, frequently with 4 central perforations, densely branched, oval to elongate and distally rounded, up to 160 μ m long, intergrade with elongate plates.

Colour(live and preserved).White, dorsally and ventrally.

Distribution. Northern Territory (Darwin), to Western Australia (Perth); 0– 22 m.

Remarks. The dorsal and lateral tube feet are not conspicuous, and were not noticed by H. L. Clark (1938). Psolus spinuliferus H. L. Clark, 1938 is reassigned here to Psolidium Ludwig. The distinguishing characters of Psolidium spinuliferus (H. L. Clark) are the predominantly single-layered scales with vertical digitiform marginal spire. The type specimen (MCZ no. 1669) was taken off the Eighty Mile Beach near Broome in northwestern Australia, at 18– 22 m.