Taeniogyrus tantulus 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 : 61-62

Taeniogyrus tantulus O’Loughlin sp. nov.

Figures 4c,d, 6, 7

Material examined. Holotype: Victoria, East Gippsland, Ninety Mile Beach, off McGaurans Beach , 800 m offshore, 10 m, fine sand, strong currents, LVWSB: SWOP 1, stn 7, Site 2, 31 Dec 1979, data from J. Carey and J. Watson, NMV F59198 .

Paratypes: Type locality and date, F59199 (11, with many microscope slides).

Other material. Type locality and date, F82710 (many); stn 6, 31 Oct 1979, F80938 (many).

Description. Up to 11 mm long, 2 mm diameter at oral and anal ends (preserved); preserved form commonly with oral and anal ends swollen, mid-body contracted and narrow, anterior dorsal body and tentacles overhang ventral body and tentacles; tentacles digitate, 10, each with 4–5 pairs of digits, longest pair distally, shortest pair proximally; calcareous ring with 5 radial 5 interradial plates fused to form narrow ring; radial plates low, with anterior narrow indentation between 2 low rounded projections, shallow concave posterior indentation; interradial plates with anterior indentation with 1 lateral low rounded projection, shallow concave posterior indentation; single dorsal stone canal, madreporite; 1 polian vesicle, ventral; narrow band of ciliated funnels along mid-dorsal interradius, on both sides of mesentery attachment; 2 unbranched gonad tubules, 1 on each side of dorsal mesentery, joined dorsally at shared gonoduct.

Body wall ossicles wheels, sigmoid hooks: wheels adjacent to longitudinal muscles in interradii of body wall, sparse in ventral interradii, wheels only ossicles anteriorly, wheels with rounded hexagonal form, 6 spokes, inner margin of rim parallel to outer margin, inner margin with continuous teeth, wheel diameters 40–104 μ m; sigmoid hooks absent anteriorly, scattered throughout interradii in mid-body, more numerous and slightly smaller than wheels, outer curved side of some hooks with spinelets, hook lengths 60–80 μ m. Tentacles with rod ossicles: rods not swollen centrally, ends with short lobed branches, rods lacking side branches or denticulations, rods 40–64 μ m long.

Colour (preserved). White, translucent.

Distribution. Eastern Victoria, East Gippsland, offshore sediments; 11 m.

Etymology. From the Latin tantulus (so small), referring to the very small size of specimens of this species.

Remarks. T. tantulus sp. nov. is distinguished in the key (above) from the other species of Taeniogyrus Semper in southern Australia. It is a very small holothuroid, extremely abundant in the off-shore sublittoral sediments of east Gippsland. Data from Jan Watson (pers. comm.) gives estimated populations at Stns 6 and 7 of 13,870 per square m. Jan noted (pers. comm.) that nearby sites had only a few individuals. There was no evidence of internal brood-protection or fissiparity in the many individuals examined, but such reproductive strategies could be seasonal. The only material examined here was collected in mid-summer.