Massinium melanieae O’Loughlin, 2012

O’Loughlin, P. Mark, Barmos, Shari & VandenSpiegel, Didier, 2012, The phyllophorid sea cucumbers of southern Australia (Echinodermata: Holothuroidea: Dendrochirotida: Phyllophoridae), Memoirs of Museum Victoria 69, pp. 269-308 : 290

Massinium melanieae O’Loughlin sp. nov.

Figures 13a , 14

Material examined. Holotype. Southern Australia, Great Australian Bight, Southern Surveyor cruise SS01/00 stn 378, 31º50'S 130º46'E, 55 m, 13/ 14 May 2000, NMV F174897 .

Diagnosis. Massinium species up to 42 mm long, up to 24 mm diameter (preserved, tentacles withdrawn), slight oral to anal taper, thin firm body wall; exterior anal scales not detected; 20 tentacles, 5 pairs of large, 5 pairs of small; complete uniform cover of small and large tube feet, diameter up to 0.4 mm; white tubular composite calcareous ring 25 mm long; radials up to 3 mm wide, anterior taper with apical notch; inter-radials up to 2 mm wide, taper to anterior point, distal indentation closed by narrow calcareous posterior bridge creating oblong non-calcareous section; 4 polian vesicles, shorter than calcareous ring; stone canal extending from end of calcareous ring with madreporite free in coelom (dissected condition); cylindrical longitudinal muscles, not divided; gonad tubules thin, branched.

Lacking mid-body wall ossicles; tube feet with endplates only, diameter up to 320 µ m, irregular perforations, small central, larger peripheral; tube feet lacking support ossicles; peri-oral region with abundant regular tables, discs oval to rounded rectangular, up to 96 µ m long, 4 large central and numerous small peripheral perforations, spires up to 24 µ m long, 2 pillars each with up to 5 blunt apical spines, some bifid; tentacle branches with thin rods, knobbed or finely perforate distally, up to 104 µ m long; tentacle trunks lacking ossicles; inner wall of tubular calcareous ring with rods up to 104 µ m long, widened and rounded distally, each end with up to 8 perforations; anal ossicles scales, endplates, tables; scales single-layered, thick, irregular, perforated; endplates about 160 µ m diameter; tables irregular, frequently about 16 disc perforations, 3 or 4 large central, small peripheral, 2 pillars, each with blunt apical spines, most discs up to 72 µ m long, pillars about 40 µ m high.

Colour (preserved). Body off-white with grey-brown irregular patches; tentacle trunks grey, branches grey-brown.

Type locality. Southern Australia, Great Australian Bight, 55 m.

Etymology. Named for Melanie Mackenzie, collection curator in the Department of Marine Biology in Museum Victoria, and valued colleague in echinoderm systematic research.

Remarks. Massinium melanieae O’Loughlin sp. nov. is erected for a single specimen in good condition. The type locality is unlikely to be sampled again in the foreseeable future and we judge that it is important to erect this species. The distinguishing combination of diagnostic characters for Massinium melanieae O’Loughlin is given in the key (above).

Figures

Figure 13. Photos of preserved specimens. a, Massinium melanieae O’Loughlin sp. nov. (holotype NMV F174897); b, Massinium vimsi O’Loughlin sp. nov. (holotype, NMV F76629) (insert: form of the calcareous ring plates); c, Massinium watsonae O’Loughlin sp. nov. (holotype, NMV F97435); d, calcareous ring, stone canal (along alimentary canal) and madreporite, and 2 polian vesicles (top left corner) of Massinium watsonae (TMAG H1988); e, colour morph of Massinium watsonae (NMV F174899) (insert: form of the calcareous ring plates); f, exceptional calcareous ring from specimen of Phyllophorella thyonoides (H. L. Clark, 1938) with posterior prolongations joined as in Massinium species (WAM Z31975) (insert: form of the calcareous ring plates).

Figure 14. SEM images of ossicles from holotype of Massinium melanieae O’Loughlin sp. nov. (NMV F174897). Regular tables from peri-oral body wall (top left); mid-body tube foot endplate (top right); large irregular table from anal region (central right); thin rods from tentacle branches (bottom right).