Pseudostichopus elegans ( Koehler and Vaney, 1905 ) O'Loughlin & Ahearn, 2005

O'Loughlin, P. Mark & Ahearn, Cynthia, 2005, A review of pygal-furrowed Synallactidae (Echinodermata: Holothuroidea), with new species from the Antarctic, Atlantic and Pacific oceans, Memoirs of Museum Victoria 62 (2), pp. 147-179 : 170

Pseudostichopus elegans ( Koehler and Vaney, 1905) comb. nov.

Figures 9c , 11c, d

Filithuria elegans Koehler and Vaney, 1905: 81 , pl. 6 figs 1, 2, pl.

12 figs 29–31.— Heding, 1940: 357, 362–363, fig. 18.

Material examined. NE Pacific Ocean, off Oregon, 3021 m, USNM E16815 (1); 1008097 (3); 2510 m, USNM E16505 (3); NMV F97447 (1); 2884 m, USNM E16497 (1); 2710 m, E16490 (4); NMV F97446 (1).

Description. Up to 145 mm long; elongate, subcylindrical, tapering anteriorly and posteriorly, flat ventrally, high convex dorsally, sometimes brim weakly developed; body wall thick, leathery, firm thin outer layer, soft thin semi-gelatinous inner layer; surface smooth dorsally and laterally, rugose ventrally; paired radii with double series of long tapering papillae, very thin distally, longest in upper dorsolateral series, up to 22 mm long, smaller in lower dorsolateral and double ventrolateral series; small tube feet all over body, up to 0.5 mm long, 0.3 mm diameter; ossicles in tentacles, papillae, tube feet; tentacle ossicles abundant tapering rods, long to short, thick to thin, with or lacking central thickening, rare short branching, spinous or smooth, up to 490 µm long; large dorsal papillae with rods similar to tentacles, some more sharply and abundantly spinous, shorter, up to 260 µm long; small papillae and tube feet with thick to thin rods, many with central swelling, bluntly spinous or smooth, short, up to 160 µm long.

Colour. Body violet-brown to reddish-brown to off-white; gonad tubules and respiratory trees pale brown; longitudinal muscles chocolate to reddish-brown.

Distribution. Bay of Bengal, off Andaman Is., 741 m ( Koehler and Vaney, 1905); Indian Ocean, off Sumatra, 750 m ( Heding, 1940); North-east Pacific Ocean, off Oregon, 2510–3021 m (this paper).

Remarks. Koehler and Vaney (1905) and Heding (1940) reported single specimens of Filithuria elegans . Filithuria Koehler and Vaney is considered above to be a junior synonym of Pseudostichopus Théel. The distribution of P. elegans is extended here from the Indian Ocean to the NE Pacific Ocean, to greater depths. Amongst Pseudostichopus species the distinguishing characters of P. elegans are: distinctly long papillae on the paired radii; numerous tapered rod ossicles in the papillae.

Figures

Figure 9. Characters of Pseudostichopus. a, drawing of transverse section of mid-body (as in P. mollis); b, cylindrical longitudinal muscles detached from calcareous ring (P. tuberosus sp. nov., NMV F101864, paratype); c, dorsolateral radial papillae (P. elegans, NMV F97447, papillae up to 8 mm long); d, drawing of part of gonad, unbranched tubules, arising separately along gonoduct; e, two series of unbranched gonad tubules along gonoduct (P. mollis, TM H2004); f, gonad (P. tuberosus sp. nov., paratype, USNM 1008333).

Figure 11. Tentacle ossicles (SEM). a–b, Pseudoshichopus aemulatus (USNM 1025525, paratype). c–d, P. elegans (USNM E16505). e–f, P. mollis (USNM E48656). g–h, P. tuberosus sp. nov. (USNM E16721, holotype). i–l, P. peripatus, i (USNM 12198), j (USNM E38794), k (USNM E38796), l (USNM E49349).