Achiridota smirnovi, 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 : 67-68

Achiridota smirnovi sp. nov.

Figure 2a ; table 2

chiridotid sp. MoV 2019 O’Loughlin et al., 1994: 553, 554.

Material examined. Holotype. Eastern Antarctica, Prydz Bay, Amery Depression, 68º06'S 72º15'E, 788 m, stn ANARE AA93–60 , M. O’Loughlin, 28 Jan 1993, NMV F68687 .

Paratype. Prydz Bay , edge of Fram Bank, 66º55'S 69º12'E, 518 m, stn ANARE AA93–75 , 31 Jan 1993 , NMV F68686 .

Diagnosis. Achiridotid species up to 15 mm long (posterior end of body missing on 11 mm long holotype); 12 peltato-digitate tentacles, 4 pairs of digits per tentacle, pair distally, increasing in size distally; tentacle ampullae cup-like, on anterior edge of non-calcareous ring; lacking ossicles in body wall, tentacles; lacking calcareous ring; single polian vesicle; madreporite on long straight canal; gonad tubules with multiple branching; lacking ciliated funnels.

Colour (preserved). Holotype with reddish-brown flecking on semi-translucent off-white body, red-brown tentacles; other specimen semi-translucent off-white, tentacles pale reddishyellow.

Distribution. Eastern Antarctica, Prydz Bay, 518– 788 m.

Etymology. Named for Alexei Smirnov (Zoological Institute of the Russian Academy of Sciences, St. Petersburg) in recognition of his description of the first myriotrochid species from the Antarctic shelf, and with appreciation of his significant contribution to the systematics of Apodida .

Remarks. Apodid specimens collected from Prydz Bay during the same cruise as these specimens, and preserved in the same way (directly in 70% ethanol), have retained their ossicles in good or slightly eroded condition. It is most unlikely that the complete absence of calcareous parts in the two specimens on which Achiridota smirnovi sp. nov. is based is a result of preservation.

Generic assignment of this new species is problematic because of the absence of a calcareous ring and body wall ossicles. But the tentacles do arise from anterior cup-like depressions around the non-calcareous ring, as in Achiridota H. L. Clark. The species has the Achiridota diagnostic characters of: 12 peltato-digitate tentacles; single polian vesicle; lacking ossicles in tentacles, body wall; lacking ciliated funnels. But the madreporite is situated at the end of a long straight canal, and is not close to the water canal. We assign the new species to Achiridota Clark with reservations because of the absence of a calcareous ring and position of the madreporite distant from the ring canal. These two characters distinguish Achiridota smirnovi sp. nov. from Achiridota inermis (Fisher) and Achiridota profunda Heding. Additional diagnostic distinctions are the presence of 6–8 pairs of tentacle digits in Achiridota inermis (4 pairs in A. smirnovi ), and 7–8 pairs of tentacle digits and unbranched gonad tubules in Achiridota profunda (branched in A. smirnovi ).

Figures

Figure 2. a, drawing of tentacle and part of non-calcareous ring of Achiridota smirnovi sp. nov. (Prydz Bay; holotype, NMV F68687); b, drawing of tentacle and part of calcareous ring of Kolostoneura griffithsi sp. nov. (S Orkney Is; holotype, NMV F168634).