Echinocucumis kirrilyae O'Loughlin, 2009, sp. nov.

Echinocucumis kirrilyae sp. nov.

Figures 1a–d; table 1.

Material examined. Holotype. Eastern Antarctica, off Enderby Land, 65°48'S 53°16'E, 180–209 m, BANZARE stn 41, 24–25 Jan 1930, SAM K2457.

Diagnosis. Body 6 mm long (excluding tentacles); body wall calcareous with test of irregular, imbricating, spired scales; body fusiform, lacking oral and anal cones; mouth anterior; anus dorso-posterior; 10 sub-equal sub-digitiform tentacles, with trunk and few short branches; single irregular spaced radial series of latero-ventral tube feet, a few tube feet on anterior and posterior mid-ventral radius; lacking tube feet dorsally and laterally; calcareous ring lacking posterior prolongations (ring fragmented); gonad tubules branched proximally; longitudinal muscles flat.

Body wall ossicles single-layered perforated plates, up to 424 µ m diameter, irregular form around typically 4 large central perforations, tree-like spire arising centrally on plate between large perforations, up to 280 µ m high, thick basal trunk branching openly, distal stout spines. Tentacle ossicles bent and curved rods, with central apical and terminal perforations, margin bluntly spinous; rods up to 272 µ m long.

Distribution. Eastern Antarctica, off Enderby Land, 180– 209 m.

Etymology. Named for Kirrily Moore, Technical Officer in the Tasmania Museum and Art Gallery, with appreciation of her gracious assistance in providing access to Antarctic and Sub-Antarctic holothuroid material.

Remarks. The single specimen is very small, but has distinctive and unique diagnostic characters. The new species is referred with reservations to Echinocucumis Sars, diagnosed most recently by Pawson (1970), because it has: 10 tentacles; calcareous ring lacking posterior prolongations; ventral radial tube feet; body plated with imbricating scales; ossicles single-layered perforated spired plates. It is referred with reservations because: body is fusiform and lacks oral and anal cones; tentacles are sub-digitiform and sub-equal; plates/ scales are less than 500 µ m diameter; spires arise centrally on the plates, between large central perforations. The ossicles show similarities with illustrations by Hansen (1988) of ossicles of very small specimens of dendrochirotid species of Staurocucumis and Psolicucumis. Hansen (1988) noted that the form of ossicles in juveniles raised doubts about the distinction between dactylochirotids and dendrochirotids. The presence of gonads in the type specimen indicates that it is not a juvenile. Echinocucumis kirrilyae sp. nov. is distinguished diagnostically within the dactylochirotids by the tree-like form of the centrally placed ossicle spires, each comprising a trunk with spreading, distally spinous, branches.