Prototrochus linseae, O’Loughlin & VandenSpiegel, 2010

O’Loughlin, P. Mark & VandenSpiegel, Didier, 2010, A revision of Antarctic and some Indo-Pacific apodid sea cucumbers (Echinodermata: Holothuroidea: Apodida), Memoirs of Museum Victoria 67, pp. 61-95 : 73

Prototrochus linseae sp. nov.

Figures 1a , 7 ; table 2

Material examined. Holotype. Antarctica, Scotia Sea , South Shetland Is, 62.53°S 61.83°W, 192 m, BAS stn LI–EBS–4, 4 Mar 2006, NMV F168631 .

Paratypes. Type locality and date, NHM 2010.50 (1) ; RBINS IG 31 459 (2, SEM).

Other material. South Shetland Is, 61.61°S 55.22°W, 1544 m, BAS stn EI–EBS–1, 12 Mar 2006, NHM 2010.53 (1).

Diagnosis. Myriotrochid species up to 7 mm long; 10 tentacles; lacking tentacle rods; scattered myriotrochid wheels only in body wall; wheel ossicle diameters 125–137 µ m, spokes 10–11, teeth 22–24, spokes/teeth % 45, hub diameters 30–34 µ m, hub diameter/wheel diameter % 24.0–24.7, teeth length/wheel diameter % 12.9–13.0.

Colour (preserved). Body pale yellow-brown to off-white, translucent; tentacles yellow.

Distribution. Antarctica, Scotia Sea, South Shetland Is, 192– 1544 m.

Etymology. Named for Katrin Linse (British Antarctic Survey), in appreciation of her role in the BAS BIOPEARL expeditions and the collection of specimens studied here, and with gratitude for her gracious collaboration in making BAS specimens available for this study and providing relevant data.

Remarks. Most of the 12 species referred to their new genus Prototrochus by Belyaev and Mironov (1982) lack tentacle ossicles, as does Prototrochus linseae sp. nov. Most of the species lacking tentacle ossicles are from the deep trenches (6450–10700 m in Belyaev and Mironov 1882). Only Prototrochus bipartitodentatus ( Belyaev and Mironov, 1978) has been recorded from the Antarctic (South Sandwich Trench, 7700–8100 m). It has external teeth around the rim of the wheels that Prototrochus linseae does not. Belyaev and Mironov (1982) list three shallower species (540–3000 m), two from the Mediterranean Sea and Prototrochus australis (Belyaev and Mironov, 1981) from the Tasman Sea. O’Loughlin and VandenSpiegel (2007) list three additional species from the Tasman Sea: Prototrochus burni O’Loughlin, 2007 *, Prototrochus staplesi O’Loughlin, 2007 * and Prototrochus taniae O’Loughlin, 2007 * (*all in O’Loughlin and VandenSpiegel 2007). As demonstrated by reference to Table 1 and Figure 10 in O’Loughlin and VandenSpiegel (2007), Prototrochus linseae is distinguished from the four Tasman Sea Prototrochus species by the form of the wheels: smallest wheels; largest teeth; widest uniformly broad spokes, with sharp constriction at the hub; largest hub.

Figures

Figure 1. Colour photos of preserved specimens of apodid species. a, Prototrochus linseae sp. nov. (7 mm long; S Shetland Is; holotype, NMV F168631); b, Kolostoneura griffithsi sp. nov. (12 mm long; insert drawings of tentacle rods, 96–112 µm long; S Orkney Is; holotype, NMV F168634); c, Scoliorhapis biopearli sp. nov. (6 mm long; insert drawing of tentacle rod, 115 µm long; S Shetland Is; holotype, NMV F168633); d, Scoliorhapis massini sp. nov. (20 mm long; Shag Rocks; holotype, NMV F168635); e, Sigmodota magnibacula (Massin and Hétérier, 2004) (15 mm long; S Orkney Is; NMV F168629); f, Taeniogyrus antarcticus Heding, 1931 (15 mm long; S Orkney Is; NMV F168630).

Figure 7. Prototrochus linseae sp. nov. (S Shetland Is; RBINS IG 31 459). a, SEM of plates of the calcareous ring with prominent single anterior projections; b, SEM of wheels from the body wall.