Australian species of Psolidium Ludwig (Echinodermata: Holothuroidea: Psolidae) Author O’Loughlin, P. Mark Author Ahearn, Cynthia text Memoirs of Museum Victoria 2008 2008-12-31 65 1 22 https://museumsvictoria.com.au/collections-research/journals/memoirs-of-museum-victoria/volume-65-2008/pages-23-42/ journal article 10.24199/j.mmv.2008.65.2 1447-2554 8065020 Psolidium nigrescens H. L. Clark Psolidium nigrescens H. L. Clark, 1938: 505-507 , fig. 50.—H. L. Clark, 1946: 414–15 .— Cannon and Silver, 1987: 29 .—Rowe (in Rowe and Gates), 1995: 318. Material examined . New South Wales , Broken Bay , Hawkesbury River , Yeomans Bay , Smith-MacIntyre Grab , mud sediment, G. Phillipson , Oct 1992 (specimen not lodged in museum) ; Port Jackson , Middle Harbour , N bank W of Spit Bridge , 33°48'S 151°15'E , steeply sloping bottom with telestacean bed, live and dead mussels, Tethia sp. and compound ascidians, 8 m , J. K. Lowry , 9 Jun 1981 , J24097 (1); Botany Bay , off Dolls Point , dredged, 7–11 m , D. F. McMichael , Oct 1949 , J6789 (4); Port Hacking , Gunnamatta Bay , 34°04'30"S 151°08'54"E , on shells of Anadara , I. Bennett , 2 Nov 1948 , AM J6821 (6) ; Batemans Bay , Clyde R, edge of channel near southern bank downstream from Princes Hwy road bridge, 35°42'34"S 150°11'3"E , 5 m , clump of hairy mussels, Australian Museum party, 30 Mar 2004 , J24092 (3). Description . Psolidium species up to 40 mm long (preserved); body elongate; dorsal and lateral body scales thick, up to 4 mm wide, covered by fairly thick integument; scales tapered to projecting rounded point orally and anally; dorsal and lateral tube feet conspicuous, up to 5 pass through a scale. Sole with peripheral band of tube feet, about 5 wide, outermost tube feet not smaller; mid-ventral radial series of tube feet predominantly 2 wide. Dorsal and lateral ossicles: multi-layered ossicles (scales) with tube foot canals; thick knobbed buttons, 3-10 perforations, up to 192 μ m long, intergrade with multi-layered ossicles; branched rods with pointed ends (“thorn” ossicles), irregular form, 3-5 arms, flat to 3-dimensional, up to 56 μ m long; rosettes, densely branched, up to 40 μ m long. Sole ossicles:perforated plates, slightly concave, irregularly round, knobbed marginally, up to 14 perforations, up to 152 μ m long; very shallow, marginally knobbed, 4-perforation cups and cupped crosses, typically 96 μ m long; rare rosettes; rare “thorn” ossicles. Tentacle ossicles include: rosettes, up to 40 μ m long; “thorn” ossicles, up to 40 μ m long. Colour (preserved) . Dorsal and lateral body black to brown to dark grey, with fine white spotting over scales; tube feet off-white; sole pale brown to cream, with some fine brown flecking; tentacle trunks dark brown, tentacle dendritic ends off-white. Distribution . Eastern Australia , central New South Wales , Broken Bay to Batemans Bay, estuarine; 0– 11 m . Remarks . The distinguishing characters of Psolidiumnigrescens H. L. Clark, 1938 are the “thorn” ossicles in the body wall, and very dark brown to black colour.