Thyone tourvillei 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 : 306

Thyone tourvillei O’Loughlin sp. nov.

Figures 17f , 24

Material examined. Holotype. Eastern Tasmania, 37 km NE of Cape Tourville, RV Franklin stn SLOPE 85, 41º56'S 148º35'E, upper continental slope, 124 m, G. C. B. Poore et al., 30 Oct 1988, NMV F174902 (1, small, damaged, 15 mm long).

Paratype. Eastern Bass Strait , VIMS, RV Tangaroa , 81–T–1 stn 170, 38º52.6'S 148º25.2'E, 140 m, mud / sand, 15 Nov 1981, NMV F76627 (1, small, damaged, 6 mm long) .

Diagnosis. Thyone species 15 mm long (preserved body and partly extended tentacles), up to 3 mm diameter, body cylindrical, rounded ends, body wall soft; external anal scales not detected; 11 tentacles (some lost in holotype), large pairs, small singly; complete close cover of tube feet, single contiguous series on each side of longitudinal muscle interior attachments, more scattered inter-radially, diameter about 0.2 mm; composite calcareous ring; radial plates tapered anteriorly with terminal split, long paired composite posterior prolongations, narrowing distally; inter-radial plates tapered to anterior point, not composite, lacking posterior extensions, contiguous posterolaterally with composite radial posterior extensions; stone canal and madreporite lie on calcareous ring; single polian vesicle.

Mid-body wall with tables, regular, discs oval, up to 64 µ m long, 4 narrow perforations in cross formation centrally, 4 larger corner perforations, single pillar spire with apical spines, spire 24 µ m long; tube feet with endplates and endplate support tables and plates; endplates with small central perforations, transversely elongate perforations marginally, marginal denticulations, diameters up to 144 µ m; tube foot support tables with curved narrow disc, frequently 4 central perforations, 2 distally, discs up to 88 µ m long, single pillar spire 24 µ m long; tube foot support plates, slightly curved, sub-rectangular, larger perforations centrally, smaller distally, digitiform projections on one edge, up to 160 µ m wide; tentacles with rods, tables, rosettes; rods up to 280 µ m long, up to 4 distal perforations, up to 2 spines along shaft; rosettes up to 80 µ m long.

Colour (preserved). Body and tube feet off-white, tentacles pale brown.

Type locality. Eastern Tasmania, off Cape Tourville , 124 m.

Distribution. Eastern Bass Strait and Tasmania, 124– 140 m.

Etymology. Named for the type locality, Cape Tourville, in eastern Tasmania; in turn named for the French naval commander Comte de Tourville by the explorer Nicolas Baudin.

Remarks. Both the holotype and paratype of Thyone tourvillei O’Loughlin sp. nov. are damaged, but calcareous components are well-preserved and the specimens sufficiently intact to provide distinctive diagnostic characters for the new species. The diagnostic characters of this new species are not those of any current phyllophorid genus.

Thandar 1989 erected subfamily Sclerothyoninae Thandar, 1989 with two monotypic genera Sclerothyone Thandar, 1989 and Temparena Thandar, 1989 to accommodate two previously erected species. In both genera the calcareous ring is not tubular and is similar to that in the new species Thyone tourvillei . But in both Thandar genera the tube foot distribution is radial only, there are eight large and two small tentacles, and the tables have spires with two pillars. Neither genus is suitable for referral of the new species.

We refer this new species to Thyone Oken on the basis of tube feet and ossicle characters, but with considerable reservation because of the single pillar spire tables, Sclerothyoninae-like calcareous ring, and uncertain tentacle state. We are reluctant to erect a new genus on damaged and very small specimens, with uncertainty about tentacle characters, and with a major revision needed of genus Thyone . Thyone tourvillei 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 24. SEM images of ossicles from holotype of Thyone tourvillei O’Loughlin sp. nov. (NMV F174902). Mid-body wall tables with single pillar spires (top); rods and rosettes from tentacles (bottom).