Molpadiodemas constrictus, 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 : 153-157

publication ID

https://doi.org/ 10.24199/j.mmv.2005.62.5

persistent identifier

https://treatment.plazi.org/id/116087F5-FFAE-FFEA-FC91-7F39FB771862

treatment provided by

Felipe

scientific name

Molpadiodemas constrictus
status

sp. nov.

Molpadiodemas constrictus View in CoL sp. nov.

Figures 3c–e View Figure 3

Material examined. Holotype. North Atlantic Ocean , Puerto Rico Trench, 20°08'N, 65°27'W, 7086 m, RV Gilliss, 20 Jan 1973, USNM 1022814 About USNM . GoogleMaps

Paratypes. Type locality and date, USNM 1022815 About USNM (20) ; NMV F101857 About NMV (5).

Other material. Type locality and date, USNM 1022816 About USNM (90) ; NMV F101856 About NMV (10).

Description. Up to 62 mm long; body rounded anteriorly, frequently strongly tapered and narrow posteriorly, dorsoventrally depressed, low convex dorsally, flat ventrally frequently with longitudinal median depression, body typically with one rarely two deep transverse constrictions most frequently posterior to calcareous ring, body rounded ventrolaterally sometimes subacute; body wall thick, firm, soft, semi-gelatinous; even cover of very small tube feet all over body, some very thin erect, about 0.2 mm long, some lying on body, cylindrical, thin, typically 0.8 mm long, 0.15 mm diameter, up to 1.5 mm long, rarely contiguous; longitudinal muscles flat, broadly attached, narrow, slightly thickened; no ossicles found.

Colour. Body dark mauve-brown (largest), pale grey-brown to translucent (smallest), largest sometimes with dark red-brown markings dorsally, sometimes with even cover of mauve to brown spots ventrally creating a mottled appearance; largest tube feet body colour, smallest off-white.

Etymology. From the Latin constrictus (drawn together,

contracted), referring to the characteristic deep transverse constrictions on specimens.

Distribution. North Atlantic Ocean, Puerto Rico Trench, 7086 m.

Remarks. The transverse constrictions of the body are growth constrictions. They closely resemble similar growth constrictions observed by one of us (M.O’L) in the fissiparous cucumariid species Squamocnus aureoruber O’Loughlin and O’Hara, 1992 . Emson and Wilkie (1980) listed six fissiparous holothurian species, four of them aspidochirotids. M. constrictus is judged to be fissiparous.

The material was at some stage preserved in formalin solution, which might account for the complete absence of ossicles. Amongst Molpadiodemas species the distinguishing characters of M. constrictus are: body form typically with a transverse constriction; distinct posterior taper; body colour frequently with dark markings dorsally and mottled ventrally; minute thin erect tube feet; absence of ossicles.

NMV

Museum Victoria

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