Molpadiodemas villosus ( Théel, 1886 ) 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 : 164-165

publication ID	https://doi.org/ 10.24199/j.mmv.2005.62.5
persistent identifier	https://treatment.plazi.org/id/116087F5-FFB9-FFF2-FCA9-7A9CFEDD1934
treatment provided by	Felipe
scientific name	Molpadiodemas villosus ( Théel, 1886 )
status	comb. nov.

Treatment

Molpadiodemas villosus ( Théel, 1886) View in CoL comb. nov.

Table 3, Figures 2a, e View Figure 2 , 7d–f View Figure 7 , 8q–t View Figure 8 , 12a–d View Figure 12

Pseudostichopus villosus Théel, 1886: 170–171 (part; syntypes from Challenger stns 157, 244 only; not Pseudostichopus villosus var. violaceus Théel, 1886 ).

Material examined. Lectotype (designated here). North-west Pacific Ocean , off Japan, 35°22'N, 169°53'E, 5304 m, Challenger stn 244, BMNH 86.10 .2.147. GoogleMaps

Other material. Paralectotype, Southern Indian Ocean , 53°55'S, 108°35'E, 3566 m, Challenger stn 157, BMNH 86.10 GoogleMaps .2.155 (1).

Northern Pacific Ocean, Clarion-Clipperton Fracture Zone, no depth, USNM E48492 (1); Galapagos Is, 3667 m, E9929 (1); South-east Pacific Basin, N of Amundsen Sea, 5042–5045 m, USNM 48659 (3); 4709 m, E49280 (1); 4676 m, E48584 (1); 4740–4742 m, E49333 (5); N of Marie Byrd Land, 4682 m, E48658 (1); Ross Sea, 3495–3514 m, E48583 (4); 2005–2010 m, E48620 (7); NMV F101859 (2).

North Atlantic Ocean, North American Basin, 3264-3356 m, USNM 1006292 (1).

Scotia Sea, S of South Georgia I., 3413–3446 m, USNM E48634 About USNM (1); E48633 (8) ; NMV F98745 About NMV (2); 2742–2758 m , USNM E48640 About USNM (2) ; NMV F101860 About NMV (2); 2384–2416 m , USNM E49257 About USNM (1, with commensal gastropods); South Georgia I., 3166-3255 m , USNM E48609 About USNM (1); South Shetland Is , 681–1409 m , E48571 (2); N of Bellingshausen Sea , 4941 m , E48589 (1).

Description. Up to 110 mm long; body variably elongate and tapered anteriorly and posteriorly; subcylindrical, lacking brim, sometimes sac-like; lacking globigerine or sponge spicule or grit attachments; body wall thick semi-gelatinous to thin firm, surface smooth to wrinkled and pustulose; tube feet small, soft, hair-like, never erect, close to sparse cover over whole body, dorsally typically 1.5 to 2.0 mm long, up to 3.0 mm long, 0.05 mm diameter; tube feet sometimes matted ventrolaterally, anteriorly and pygally, typically 1.0 to 1.3 mm long, 0.2 mm diameter; ventral tube feet frequently withdrawn, if extended typically 0.5 mm long, 0.2 mm diameter; gonad tubules unbranched and multibranched; ossicles in tentacles and gonad; tentacle ossicles abundant, variable form, large, up to 530 µm long, frequently rods perforated entire length, rods variably with mid-rod swelling, thick rods with branches at ends intertwined to create mesh, thick rods with lateral joined branches creating mesh, large mesh ossicles (intertwined, joined rods, not perforated plates), club-shaped rods with minute perforations, smooth thick to thin rods tapered at ends, sometimes blunt spines, some knots of thick irregularly branching rods; gonad ossicles abundant, long thin branched and unbranched irregular rods, many with lateral mesh with large perforations, many thick smooth rods with central knobbed swelling, many central knobs elongating into short thick branches which fuse to create perforations, up to 270 Μm long.

Colour. Greyish-white, sometimes with reddish-brown hue; tube feet off-white, sometimes pale brown ventrolaterally.

Distribution. Atlantic, Indian, Pacific and Southern Oceans, Ross Sea, N of Amundsen Sea, N of Bellingshausen Sea, Scotia Sea; 681–5304 m.

Remarks. Théel (1886) listed ten syntypes of P. villosus (nominal subspecies villosus ), plus a type of his variety P. villosus var. violaceus . All have been examined in this study. Théel noted the “villous” appearance of the specimen from stn 244 and it is this one we have chosen as lectotype. One other, from stn 157, is a paralectotype. Of the others, the one from stn 216 is not conspecific and is described above as the new species, M. neovillosus .

Four of the remaining types are also not P. villosus . The type of the variety and three of the syntypes are referred below to the species Molpadiodemas violaceus ( Théel, 1886) . The seventh syntype (Southern Pacific Ocean, off Chile, 42°43'S, 82°11'W, 2652 m, Challenger stn 302, BMNH 86.10.2.153) is not P. villosus . It was 80 mm long, and had a close cover of globigerines, strong transverse ridges ventrally, an acute serrated ventrolateral margin, and cylindrical longitudinal muscles. No gonad was present. It is probably Pseudostichopus peripatus (Sluiter) , but there is insufficient evidence to confirm a determination. The three remaining syntypes are small, and remain unconfirmed paralectotypes: stn 146, BMNH 86.10.2.148 (1); stn 156 (of two lots from this Station the lot with the P. villosus syntype), BMNH 86.10.2.146 (1); stn 296, BMNH 86.10.1.152 (1).

Dr Frank Rowe (pers. comm.) observed eggs or embryos amongst the tentacles of the paralectotype (stn 157), and considered the possibility of brood-protection. The observation was confirmed during this study.

The distribution of P. villosus given by O’Loughlin (2002) is not valid, since only one of the syntypes is conspecific with the designated lectotype, and most previous determinations of P. villosus are in doubt.

Amongst Molpadiodemas species, the distinguishing characters are: close to sparse body cover of small, hair-like, off-white tube feet, sometimes matted ventrolaterally and pygally; gonad ossicles.