Pseudostichopus occultatus Marenzeller, 1893

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 : 173-174

Pseudostichopus occultatus Marenzeller, 1893

Pseudostichopus occultatus Marenzeller, 1893 a: 15–17 , pl. 4 fig. 9.— Marenzeller, 1893b: 10, pl. 2 fig. 3a–c.— Perrier, 1902: 337–338.— Mortensen, 1918: 81.— Mortensen, 1927: 387–388.— Deichmann, 1930: 89–90.

Molpadiodemas occultatus .— Heding, 1940: 353–359.

Meseres occultatus .— O’Loughlin, 1998: 497.— O’Loughlin, 2002: 307, tables 1, 3.

Material examined. Syntypes. Mediterranean Sea, Crete, 35°4'N, 24°17'E, 1445 m, 31 Aug 1891, MNHN EcHh 3658 (2); USNM 18294 (2).

Description. Up to 40 mm long; encrusted with shell, sand, sponge spicule attachments; body dorsoventrally depressed, flat ventrally, low convex dorsally, acute ventrolateral margin or thin brim; body wall parchment-like, wrinkled with low reticulate ridges; appendages most evident as papillae dorsolaterally and in ventrolateral band, typically 1 mm long; ossicles in tentacles, pygal lobes, tube feet, respiratory trees; tentacle ossicles thick to thin irregular rods, some with central swellings, rare short branches, rare blunt spines, lacking mesh developments, up to 280 µm long; pygal lobe ossicles irregular perforated plates, partly double-layered, up to 400 µm long; tube foot ossicles smooth tapered rods with central swelling, typically 80 µm long, “endplates” clusters of very irregular twisted branched rods or irregular perforated plates, typically 80 µm wide; respiratory tree ossicles abundant thin, smooth, symmetrically branched, pointed rods, typically 80 Μm long.

Colour. Body surface appearance brown, body wall texture grey.

Distribution. Mediterranean Sea, 415–1445 m ( Marenzeller, 1893 a); North Atlantic, Spain, off Cape Finisterre, 363–510 m ( Marenzeller, 1893b).

Remarks. P. occultatus has the diagnostic characters of Pseudostichopus , and is returned to its original combination. O’Loughlin (2002) described thin, tubular appendages covering the whole body. These are considered here to be epibiotes. Amongst Pseudostichopus species, the distinguishing characters of P. occultatus are: short, thin, smooth, distally pointed, symmetrically branched, respiratory tree ossicles; “endplate” ossicles; irregular, partly double-layered, perforated plate ossicles in the pygal lobes.