Molpadiodemas violaceus ( 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 : 165

Molpadiodemas violaceus ( Théel, 1886) comb. nov.

Table 3, Figures 1e, i , 2f , 7g –i , 8u–x

Pseudostichopus villosus var. violaceus Théel, 1886: 172 , pl. 10 fig 6b (raised to species status here).

Pseudostichopus villosus Théel, 1886: 170–171 (part; syntypes from Challenger stns 61, 147, 325; non Pseudostichopus villosus Théel, 1886 ).

Material examined. Holotype. Pseudostichopus villosus var. violaceus Théel, 1886 . Southern Ocean , off Shackleton Ice Shelf, 62°26'S, 95°44'E, 3612 m, Challenger stn 156, BMNH 86.10 .2.156.

Other material. Pseudostichopus villosus Théel, 1886 . Syntypes. North-western Atlantic Ocean , 34°54'N, 56°38'W, 5212 m, Challenger stn 61, BMNH 86.10 . 2.145 (2); southern Indian Ocean , off Crozet I., 46°16'S, 48°27'E, 2926 m, Challenger stn 147, BMNH 86.10 . 2.154 (1); south Atlantic Ocean , off Argentina, 36°44'S, 46°16'W, 4846 m, Challenger stn 325, BMNH 86.10 .2.150 (1).

Weddell Sea, S of South Orkney Is, 3587–3660 m, USNM E48600 (1); 1008106 (4); NMV F101844 (2).

South Atlantic Ocean, Scotia Sea, South Orkney Is, 2196 m, USNM E49337 (2); 3250–3285 m , E48651 (11); NMV F101843 (2); Burdwood Bank , 3514–3642 m , USNM E48627 (1); 4026–4063 m , E48654 (2); South Sandwich Is , 5435–5453 m , E48637 (6); NMV F101842 (2); 4758 m , E48626 (1); 1190–1469 m, 1022456 (3); Drake Passage , 3788–3944 m , USNM 1008117 (1); 2324–3020 m , E48591 (1).

South Pacific Ocean, Chile, depth unknown, USNM E48636 (1); Peru-Chile Trench, 6006 m, E48611 (1); 6146–6354 m, 1022608 (2); NMV F101848 (1); 5069–5173 m, USNM 1022609 (1); SE Pacific Basin, 4731 m, E48630 (3); 4773 m, E49334 (1); 3859 m, E48657 (3); 4572–4848 m, E49366 (1); 3694 m, E48605 (2); 4682 m, 1022455 (1).

Description. Up to 220 mm long; body wall leathery, pliable, surface folded and wrinkled, sometimes mucilaginous; sparse small grit and globigerine attachments; body rounded in transverse section, tapered anteriorly, posteriorly, frequently sac-like; ventrolateral margin rounded, not distinctive, lacking brim, mouth terminal ventral; even cover of small soft cylindrical tube feet all over body, never erect, evident in small specimens only, slightly larger anteriorly and pygally, may be matted, typically 1.0 mm, long, 0.3 mm diameter, frequently withdrawn in small pits, not evident on smooth leathery body wall of largest specimens; ossicles in tentacles abundant, rare in gonad; tentacle ossicles variable, predominantly bluntly tapered rarely curved unbranched smooth thick rods with distinct knob-like central swelling, some rods lacking central swelling, some rods with bifurcate or intertwined ends, some with lateral and terminal perforations, rare blunt spines and knobs, rods frequently 250 Μm long, up to 350 µm long; gonad ossicles rarely present, straight and irregular sometimes bluntly spinous short thin rods, some with central swelling, some branching creating perforations, never mesh ossicles, up to 150 Μm long.

Colour. Brown to grey-brown to off-white; tube feet brown to pale brown to off-white.

Distribution. Atlantic, southern Indian and Pacific, and Southern Oceans, Weddell Sea, Scotia Sea, SE Pacific Basin, 2196–6354m.

Remarks. Théel (1886) established ten syntypes for Pseudostichopus villosus , and a holotype for P. villosus var. violaceus . Three of the ten syntypes of P. villosus are conspecific with the type of P. villosus var violaceus .

Amongst Molpadiodemas species, the distinguishing characters are: leathery body wall; tube feet inconspicuous in large specimens, when small even cover of soft cylindrical tube feet with some anterior and pygal matting; tentacle ossicles frequently thick smooth bluntly-tapered rods, many with large knob-like central swelling; rare presence in gonad of short, thin rod ossicles.

Figures

Figure 1. Characters of pygal-furrowed Synallactidae. a, ventral mouth and anus (M. helios sp. nov., USNM E31104, paratype, 91 mm long); b, ventral peltate tentacles, polian vesicle (P. mollis, TM H2004; anterior end dissected off); c, respiratory tree (P. mollis, TM H2004); d, drawing of dorsal posterior pygal furrow; e, posterioventral view of pygal furrow and anus (M. violaceus, BMNH 86.10.2.150); f, anterior dorsal madreporite (arrow) (P. peripatus, USNM 1008159); g, drawing of calcareous ring (radial plate right, as in P. spiculiferus); h, calcareous ring (M. crinitus sp. nov., USNM E48644, paratype); i, calcareous ring (M. violaceus, BMNH 86.10.2.145).

Figure 2. Characters of Molpadiodemas. a, drawing of transverse section of mid-body, hair-like tube foot cover, flat broadly attached longitudinal muscles (as for M. villosus); b, flat longitudinal muscles, gonad (upper left), respiratory tree (upper right) (M. porphyrus sp. nov., NMV F101871, paratype, 90 mm long); c, complete cover of tube feet (M. translucens sp. nov., USNM 1008072, paratype); d, drawing of part of gonad, branched tubules from common origin; e, gonad, flat longitudinal muscles (arrows) (M. villosus, BMNH 86.10.2.155, paralectotype); f, branched gonad tubules (M. violaceus, BMNH 86.10.2.145).

Figure 7. a–c, Meseres ustulatus sp. nov.; a, ventral view (USNM 1022566, paratype, 55 mm long); b, ventrolateral tube feet (USNM 1022493, holotype); c, tube feet (NMV F101858, paratype). d–f, M. villosus; d, ventral view (BMNH 86.10.2.147, lectotype, 90 mm long); e, ventrolateral tube feet (lectotype); f, posterior tube feet (NMV F98745). g–i, M. violaceus (BMNH 86.10.2.156, holotype, 142 mm long); g, ventrolateral view; h, tube feet of M. crinitus (left, NMV F101872, paratype) contrasted with M. violaceus (right, NMV F101848); i, tentacles (USNM 1022608).

Figure 8. Tentacle ossicles (SEM). a–d, Meseres morbillus sp. nov. (USNM E49251). e–f, M. neovillosus sp. nov. (USNM 1008458, paratype). g–h, M. pediculus sp. nov. (USNM 1008318, holotype). i–l, M. porphyrus sp. nov. (USNM E38795, holotype). m–p, M. translucens sp. nov. (USNM E48652, holotype). q–t, M. villosus, q–r (USNM E48640), s–t (USNM E9929). u–x, M. violaceus, u–v (USNM 1022608), w–x (USNM E49366).