Thyone kerkosa 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 : 300

Thyone kerkosa O’Loughlin sp. nov.

Figures 17d , 20

Material examined. Holotype. Southern Australia, Recherche Archipelago, Sandy Hook Island, 34º02'S 122º00'E, Scallop Trawl Survey 1986, L.F.B.E. Triumph, D. Richards et al., 26 July 1986, WAM Z31838 (body with tentacles and ring eviscerated and lost).

Diagnosis. Body 45 mm long (preserved), up to 15 mm diameter, cylindrical, tapered to rounded oral and anal ends, body wall soft, thick; external anal scales not detected; tentacles lost; complete close cover of small tube feet, diameter 0.3 mm; calcareous ring lost.

Body wall with table ossicles only, tables range greatly in form and inter-grade; numerous small tables with discs rounded rectangular with smooth lobed margins, smallest with typically 8 perforations, discs 48–56 µ m long, spires with 2 pillars, short blunt pointed spines apically, spires 16 µ m long; medium-sized tables with elongate oval discs, sometimes bi-lobed, up to about 40 small perforations, no perforations between disc margin and 2 large central perforations adjacent to spire, discs up to 144 µ m long, spires with 2 pillars, up to 3 cross-connections, spires up to 64 µ m long; large tables with irregular narrow tapered discs, 2 large central perforations, up to about 30 small perforations, ends of disc sometimes extended into solid nonperforate ‘tail’, sometimes solid digitiform side branches off discs, discs and tails up to 124 µ m long, spires with 2 pillars, solid, up to 3 small perforations, 2 long laterally extended apical points together as wide as disc length, pillars 48 µ m long; tube feet with endplates and table support ossicles; endplates up to 120 µ m diameter; tables with curved discs; anal ossicles tables, single and multi-layered scales.

Colour (preserved). Body pale brown.

Distribution. SW Australia, Recherche Archipelago.

Etymology. Named from the Greek kerkos (tail), with reference to the elongate tail-like extensions on some narrow table discs and some table spires apically.

Remarks. We are conscious of the limited morphological data available for the single damaged specimen on which we are erecting Thyone kerkosa O’Loughlin sp. nov. But we judge that it is important to establish this distinctive species in a work that is attempting a comprehensive treatment of southern Australian phyllophorid species. We are confident that the species belongs to genus Thyone Oken because of the distribution and size of tube feet, and similarity of the tables to those of another new Thyone species from the Upper Spencer Gulf that has a characteristic Thyone ring and tentacles (see below). Thyone kerkosa is distinguished from other southern Australian Thyone species in the key (above).

Figures

Figure 17. Photos of preserved specimens. a, holotype of Thyone flindersi O’Loughlin sp. nov. (NMV F151847) (insert: form of the calcareous ring plates); b, specimen of Thyone okeni Bell, 1884 (AM J10868); c, holotype of Thyone joshuai O’Loughlin sp. nov. (SAM K2566) (insert: form of the calcareous ring plates); d, holotype of Thyone kerkosa O’Loughlin sp. nov. (WAM Z31838); e, holotype of Thyone spenceri O’Loughlin sp. nov. (SAM K2562) (insert: form of the calcareous ring plates); f, holotype of Thyone tourvillei O’Loughlin sp. nov. (NMV F174902) (insert: form of the calcareous ring plates).

Figure 20. SEM images of ossicles from holotype of Thyone kerkosa O’Loughlin sp. nov. (WAM Z31838). Mid-body wall tables small and large tables with attenuated discs and distal spires, and tube foot endplate (bottom left).