Molpadiodemas porphyrus, 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 : 163

Molpadiodemas porphyrus sp. nov.

Figures 2b , 5l, m , 6i–l , 8i–l

Material examined. Holotype. North-west Atlantic Ocean, Carribean Sea, Venezuelan Basin, 13°30'N, 64°45'W, 3459–3503 m, Norda Thru IRCZM, RV Bartlett 1301-82, 27 Nov 1981, USNM E38795 .

Paratypes. Type locality, date, depth, USNM 1008206 (1) ; NMV F101870 (1) ; type locality, 3428–3476 m, USNM E38792 (1) ; NMV F101871 (1) ; type locality, 3422–3464 m, USNM E38797 (2).

Other material. Type locality, date, 3476–3518 m, USNM E38793 (2) ; 3967–4009 m, USNM E38799 (1) ; Caribbean Sea , off Cuba, 2997 m , E2589 (1); South-west Atlantic Ocean , off Brazil, 1227 m , E2584 (14).

Description. Up to 115 mm long; body wall thick, firmly gelatinous; some globigerines attached, no overall cover; to varying degrees flattened dorsoventrally, distinct rounded brim laterally, sometimes with slightly pustulose bulges; body covered with small soft flaccid thread-like tube feet, usually spread, sometimes matted in smaller specimens, readily lost with loss of outer body layer, typically 0.7 mm long, 0.15 mm diameter, pygally up to 1.0 mm long, 0.2 mm diameter; ossicles in tentacles and gonad; tentacle ossicles numerous, variable, curved thin spinous rods (predominant in small specimens), closely finely spinous and smooth unbranched thick to broad plate-like rods, sometimes perforated, sometimes branched and intertwined at ends, spinous or smooth mesh, up to 270 Μm long; gonad ossicles abundant to sparse, small thin rods, bluntly spinous or smooth or knobbed, branched or unbranched, some branching creating narrow mesh, up to 140 Μm long.

Colour. Very soft outer body layer brown, thick semi-gelatinous layer grey with distinct overall violet mauve hue, some sparse violet mauve colour spots; tube feet off-white.

Etymology. From the Greek porphyro (purple), referring to the violet mauve colour hue and colour spots.

Distribution. North-west and South-west Atlantic Ocean, Caribbean Sea, and off Brazil; 1227–4009 m.

Remarks. Amongst Molpadiodemas species, the distinguishing characters are: firm thick gelatinous body wall; lateral brim; grey-mauve colouration; thread-like flaccid tube feet; tentacle ossicles frequently closely bluntly spinous.

Figures

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 5. a–d, Meseres morbillus sp. nov., a, lateral view (USNM 1008093, paratype, 91 mm long); b, tentacles, ventrolateral tube feet “spotting” (NMV F101865); c, tentacles, digits (USNM E49243); d, calcareous ring (radial plate right half) (USNM 1008093, paratype). e–g, M. neovillosus sp. nov.; e, dorsal view (USNM 1008458, paratype, 71 mm long); f, pygal end, tube feet (USNM 1008458); g, ventrolateral tube feet (BMNH 86.10.2.151, holotype). h–k, M. pediculus sp. nov.; h, dorsal view, elongate form (USNM 1008318, holotype, 56 mm long); i, ventrolateral tube feet (NMV F104796, paratype); j, tentacles (holotype); k, broadly attached, relatively narrow, slightly thickened, longitudinal muscles (arrows) (paratype). l–m, M. porphyrus sp. nov. (USNM E38795, holotype, 114 mm long); l, dorsal view, thick rounded brim; m, gonad. n–o, M. translucens sp. nov. (USNM E48652, holotype, 78 mm long); n, dorsal view, longitudinal muscles visible through translucent body wall (arrows); o, tentacles.

Figure 6. Gonad ossicles (SEM). a–b, Meseres atlanticus (USNM E53278). c–d, M. helios sp. nov. (USNM E31106, holotype). e–h, M. neovillosus sp. nov. (USNM 1008458, paratype). i–l, M. porphyrus sp. nov. (USNM E38795, holotype). m–p, M. ustulatus sp. nov. (USNM 1022493, holotype).

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).