Archedota lapidea O’Loughlin, 2007

O’Loughlin, P. Mark, 2007, New apodid species from southern Australia (Echinodermata: Holothuroidea: Apodida), Memoirs of Museum Victoria 64, pp. 53-70 : 57-58

Archedota lapidea O’Loughlin sp. nov.

Figure 1

Material examined. Holotype: Victoria, western Bass Strait , VIMS, NZOI RV Tangaroa , cruise 81-T-1, BSS stn 205G, 39°13’36”S, 143°55’36”E, fine sandy shell, 85 m, 23 Nov 1981, NMV F59193 (with microscope slide of ossicles).

Paratype: Western Bass Strait , Hai Kung, cruise 81-Hk-1, BSS stn 119G, 39°06’42”S, 143°28’42”E, fine sand with abundant sponges, 92 m, 31 Jan 1981, F59194 (1; with 4 microscope slides) .

Description. Up to 17 mm long, 2 mm diameter (paratype); body wall hard, calcareous; anterior dorsal body and tentacles overhang ventral body and tentacles; tentacles withdrawn (both specimens), tentacles digitate, 10, each with predominantly 5 pairs of digits, longest pair distally, shortest pair proximally; calcareous ring with 5 radial 5 interradial plates all fused to form narrow ring; radial plates low, with anterior indentation, rounded posteriorly; interradial plates with concave anterior and posterior indentations; single dorsal madreporite; 1 polian vesicle, ventral; few ciliated funnels along dorsal alimentary canal/mesentery attachment; 2 unbranched gonad tubules, thick, 1 on each side of dorsal mesentery, joined dorsally at shared gonoduct.

Body wall ossicles plates and wheels, lacking hooks: plates densely massed throughout body wall, thick, closely spinous rim and surface, form irregularly oval with 0–6 lobed projections on rim, single wheel-spoked perforation with complex hub, typically 6 spokes, plates 48–88 μ m wide; wheels sparsely present among plate ossicles, intergrade in form with wheel-spoked plates, some with rounded hexagonal form, 6 spokes, inner margin of rim parallel to outer margin, inner margin with continuous teeth, wheel diameter 48 μ m. Tentacles with rod ossicles, ends bifurcate, curved, swollen centrally, tapering distally, rods lacking side branches or denticulations, rods 56 μ m long.

Colour (preserved). Off-white. Distribution. Western Bass Strait , 39°S 143°E, 92– 85 m.

Etymology. From the Latin lapideus (of stone), referring to the stone-like ossicles in the body wall (feminine).

Remarks. The body wall ossicle combination of rare chiridotid wheels, irregular spinous plates with single wheel-spoked perforation, and absence of hooks distinguishes Archedota lapidea O’Loughlin sp. nov. from all other chiridotid species.