Molpadiodemas morbillus, 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 : 161-162

publication ID	https://doi.org/ 10.24199/j.mmv.2005.62.5
persistent identifier	https://treatment.plazi.org/id/116087F5-FFA6-FFEF-FC91-794CFD101CFD
treatment provided by	Felipe
scientific name	Molpadiodemas morbillus
status	sp. nov.

Treatment

Molpadiodemas morbillus View in CoL sp. nov.

Figures 5a–d View Figure 5 , 8a–d View Figure 8

Material examined. Holotype. Antarctic Ocean, South Shetland Is , Bransfield Strait , Livingston I., 62°38'S, 59°37'W, 681–1409 m, RV Eltanin, USARP Cr 6 stn 430, 7 Jan 1963, USNM E48647 About USNM . GoogleMaps

Paratypes. Type locality and date, USNM 1008093 About USNM (31) ; NMV F101866 About NMV (5).

Other material. Scotia Sea, 55°01'– 59°37'S, 26°00'– 45°05'W, 1071–3040 m, USNM E48601 About USNM (4); E48653 (3); E49243 (10) ; NMV F101865 About NMV (3) ; USNM E49251 About USNM (1); E49253 (12); E49254 (49) ; NMV F101867 About NMV (5) ; USNM 1008094–1008096 About USNM (7); 1022457 (9); 1022461 (1); South Sandwich Trench , 5350 m , USNM 1071583 About USNM (8); South Shetland Is , 884–935 m , USNM 1005127 About USNM (2); 2119–2562 m , E48569 (1); W of Elephant I., 2672–3020 m , E48625 (1); N of Amundsen Sea , 4682 m , USNM 1022460 About USNM (1); 4866–4881 m , E48649 (2); 4709 m, E48650 (1); NW of Amundsen Sea , 4575–4813 m , E48631 (1).

Description. Up to 143 mm long; body tapered anteriorly and posteriorly, frequently rounded in transverse section, sometimes with transverse folds and ridges; ventrolateral margin commonly rounded, sometimes with distinct serrated margin created by transverse folds; body wall firm, soft, thin (small to medium specimens) to thick (largest specimens), surface wrinkled and pustulose; some specimens with grit or globigerine attachments; complete cover of scattered small tube feet, predominantly not extended, frequently evident as a broad ventrolateral band, frequently extended and close pygally, frequently lost with loss of outer body wall, cylindrical not thread-like when extended, not villous or matted, sometimes contiguous pygally, never ventrolaterally, typically 0.5 mm long, 0.2 mm diameter pygally and when extended ventrolaterally, 0.2 mm diameter when contracted; ossicles in tentacles only, abundant to sparse to absent, irregular rods, thick to thin to wide, some perforated, frequently narrow rods with large central knob and pointed ends, some long thin rods with closely intertwined branches at ends, some with short branches, some with blunt spines, up to 300 Μm long.

Colour. Body reddish-brown to brown, smallest grey, largest off-white; tube feet typically dark reddish-brown to chocolate, creating a spotted appearance.

Etymology. From the Latin morbillus (measles), referring to the typically spotted body appearance created by the dark-coloured tube feet.

Distribution. Amundsen Sea, Scotia Sea, 681–4881 m.

Remarks. One specimen was covered by a rhizomatous epibiote with vertical tongue-like stems, that could be mistaken as a character of the species. M. morbillus is similar to M. crinitus (above), from which it is distinguished by: smaller, usually contracted, tube feet (thick and extended in M. crinitus , typically 2.0 mm long, 0.3 mm diameter, up to 3.0 mm long, 0.5 mm diameter); tube feet which are scattered and never contiguous ventrolaterally (often matted ventrolaterally in M. crinitus ); and tube feet which are darker in colour than the body wall (same colour as body wall in M. crinitus ).

Amongst Molpadiodemas species, the distinguishing characters are: conspicuous ventrolateral band of small dark cylindrical tube feet which create a spotted appearance; tentacle ossicles irregularly present, frequently narrow rods, tapered at ends, with central knob; absence of gonad ossicles.