Actinocucumis solanderi O’Loughlin, 2014

P. Mark O’Loughlin, Melanie Mackenzie & Didier Vandenspiegel, 2014, New dendrochirotid sea cucumbers from northern Australia (Echinodermata: Holothuroidea: Dendrochirotida), Memoirs of Museum Victoria 72, pp. 5-23 : 20-22

Actinocucumis solanderi O’Loughlin sp. nov.

Zoobank LSID. http://zoobank.org:act:804F4A5E-37B6-441BBBC7-BBA118 E61036

Figures 11 , 12 .

Material examined. Holotype. N Australia, Joseph Bonaparte Gulf, 13.82°S 127.32°E, 73 m, 12 Jun 2013, WAM Z27850 (KGR specimen 29384; UF tissue lot MOLAF1438 ).

Paratype. Joseph Bonaparte Gulf , 11.04°S 129.81°E, RV Solander, 52 m, Geoscience Australia, 9 Jun 2009, NMV F202991 (1) (GA lot SOL4934 lot 23BS14; UF tissue lot MOLAF1508 ).

Description. Form elongate, sub-cylindrical, slightly pentagonal with raised radial ridges tending to create 5 oral and 5 anal valves, mouth anterior, anus posterior, slightly tapered and up-turned orally and anally, up to 55 mm long (preserved); hard, thick, calcareous body wall; 20 dendritic tentacles, about 10 large dorsally, about 10 small ventrally; tube feet conspicuous, extended, predominantly on radii in irregular paired series, largest in mid-body on radii, diameters about 1.0 mm, small tube feet (with endplates) and papillae (lacking endplates) on radii and encroaching on inter-radii, diameters about 0.3 mm; lacking anal scales; calcareous ring comprising non-fragmented radial and inter-radial plates, lacking posterior prolongations, radial plates sub-rectangular with larger anterior median notch and smaller lateral notches, inter-radial plates with long anterior taper to blunt point; single polian vesicle; gonad tubules with multiple branches; respiratory trees extending throughout the coelom.

Ossicles throughout the dorsal, ventral and peri-anal body wall are densely crowded small, thick irregular tables and reduced tables, and large, elongate smooth perforated plates; tables frequently box-like with round disc about 30–40 µ m wide with single perforation, disc width similar to spire height, spires about 25–35 µ m high with 4 pillars joined mid-spire and apically, short blunt spines apically, tables often reduced with incompletely formed and irregular disc and spire; body wall tables inter-grade in form with elongate tube foot support tables; perforated plates numerous in body wall, surface and margin smooth, up to about 240 µ m long. Tentacles with tables, rods and rod-plates, lacking rosettes; table discs irregularly round to elongate oval, central disc single perforation and few large or many small outer perforations, disc margin undulating to denticulate, discs up to about 80 µ m long, spires welldeveloped with four-pillar base, blunt spines distally and sometimes along spire, spires up to 50 µ m high; curved rods perforated along rod, margin denticulate; rod-plates thick, wide, perforate distally, sometimes bifid distally, up to 440 µ m long. Tube feet with endplates about 450 µ m in diameter; tube foot support ossicles elongate tables with narrow curved discs up to 450 µ m long and four pillar spires variably developed. Introvert with abundant tables as in tentacles.

Colour preserved off-white to grey to pale brown with a hint of residual crimson dorsally, dark brown to black small spots spaced all over body; tube feet off-white with brown disc.

Distribution. N Australia, Joseph Bonaparte Gulf, 52– 73 m.

Etymology. Named for the research vessel of the Australian Institute of Marine Science, the RV Solander, from which the King George River expedition and cruise SOL 4934 were conducted and these type specimens collected.

Remarks. The distinguishing morphological character of Actinocucumis solanderi O’Loughlin sp. nov. is the presence in the body wall of abundant small, thick, box-like tables and tables that are reduced to varying degrees.

Figures

Figure 11. Photos of preserved specimens of Actinocucumis solanderi O’Loughlin sp. nov. A, right lateral view of the preserved holotype (mouth right, 45 mm long, WAM Z27850); insert with sketch of a transverse section of the new species showing slight radial ridges and large and small tube feet and papillae; B, right lateral view of the preserved paratype (mouth left, 55 mm long, NMV F202991); C, dorsal view of tentacle crown with small tentacles ventrally (paratype NMV F202991); D, photo of the calcareous ring of the holotype; insert with sketch of the calcareous ring.

Figure 12. SEM images of ossicles from the holotype of Actinocucumis solanderi O’Loughlin sp. nov. (WAM Z27850). A, oral disc and tentacle tables, spires with 4 pillars, and tentacle rods and curved perforated rod-plates (scale bars 10 µm); B, mid-dorsal body wall reduced tables with four pillar spires (scale bar 10 µm); C, mid-ventral body wall tables, and tube foot elongate support tables and endplate fragment (two top left long scale bars 100 µm, short bars 10 µm; typical box-like table bottom right); D, peri-anal body wall reduced tables (scale bars 10 µm; typical box-like table bottom right).