Chiridota kermadeca, O’Loughlin, P Mark & Vandenspiegel, Didier, 2012

O’Loughlin, P Mark & Vandenspiegel, Didier, 2012, Sea cucumbers collected by the Kermadec Biodiscovery Expedition 2011 (Echinodermata: Holothuroidea: Apodida and Dendrochirotida), Zootaxa 3515, pp. 60-66 : 61-63

Chiridota kermadeca sp. nov.

Figures 1 & 2 .

? Chiridota rigida Semper, 1868 .— Benham, 1912: 136 (non Chiridota rigida Semper, 1867 ).

Material examined. Holotype. Kermadec Islands, Stawell Shoal, north of Stella Passage, 30.5297° S, 178.5594° W, 21–24 m, SCUBA, collected S. Keable and A. Reid, 25 May 2011, fixed and preserved 95% ethanol, AIM MA 73394 (female).

Paratype. Same site and preservation history, 20 May 2011, AIM MA 73395 (specimen and slide with cleared calcareous ring plates; male).

Other material. Boat Cove, 10 m, 15 May 2011, fixed 10% formalin, preserved 70% ethanol, AM J24973 (1); AM J25393 (2).

Diagnosis. Apodid species up to 20 mm long, up to 5 mm diameter (preserved, strongly contracted, tentacles not withdrawn); ossicles in transverse oval papillae clusters in the body wall, clusters up to 0.3 mm long, numerous and close over all of dorsal and dorso-lateral inter-radii, few and scattered on both ventral inter-radii; tentacles 10, smaller ventrally, digits 5–6 pairs per tentacle, longest distally; radial calcareous ring plates more broad than high, 2 plates with anterior notches, one notch incipiently closed, plates not perforated, inter-radial plates irregular in form, higher than broad; 4 polian vesicles; gonad tubules in holotype longer than contracted body, filled with eggs; ciliated funnels minute, in single series along both ventral inter-radii and right ventro-lateral inter-radius; body wall ossicles wheels, rods; wheels with 6 spokes, continuous teeth on inner margin, wheels larger dorsally than ventrally, diameters 40–80 µm; rods few, distinctly C-shaped, ends slightly swollen, rugose, not spinous or branched, 36–56 µm long; tentacle rods typically 70 µm long, some blunt spines along rods, 3–4 branches distally, truncate ends with few blunt spines.

Colour (preserved). Alcohol-fixed specimen body dark purplish-brown, with purplish-brown to off-while transverse oval spots (biggest 0.3 mm long), abundant and close dorsally and dorso-laterally, scattered and sparse ventrally; gonad tubules white; formalin-fixed specimen pink, with off-white spots; tentacles off-white.

Distribution. Kermadec Islands, Stawell Shoal and Boat Cove, 10– 24 m.

Etymology. Named for the Kermadec Islands as the type locality and only known distribution for this species.

Remarks. The tentacle number in Chiridota kermadeca sp. nov. is 10, not the typical 12 tentacles for species of Chiridota Eschscholtz, 1829 . This and the remaining combination of morphological characters distinguish the new species from other Chiridota species discussed with keys by Clark (1908) and Heding (1928). It is not Chiridota rigida Semper, 1867 , thought to be widespread in the Indo-Pacific oceans ( A. M. Clark & Rowe 1971), and reported previously by Benham (1912) with some reservation for the Kermadec Islands, by Rowe & Doty (1977) for Guam, by Thandar & Rowe (1989) for southern Africa, and by Rowe & Gates (1995) for Australia. Chiridota rigida has many fewer dorsal ossicle papillae, 12 tentacles, calcareous ring plates with pores, and body wall rods weakly branched, and not distinctly C-shaped. Chiridota kermadeca sp. nov. is not one of the four Chiridota species reported by Pawson (1970) for New Zealand: Chiridota carnelyensis Mortensen, 1925 (white, lacking body wall rods); Chiridota gigas Dendy & Hindle, 1907 (12 tentacles, body wall rods spinous distally, ossicle papillae merge mid-body); Chiridota nigra Mortensen, 1925 (lacking body wall rods, lacking ventral ossicle papillae, black); Chiridota mortenseni Pawson, 1962 (body wall rods spinous, tentacle rods smooth and not extensively bifurcating, radial plates of calcareous ring perforated). It is not Chiridota hawaiiensis Fisher, 1907 (12 tentacles each with 4–5 pairs of digits, ossicle papillae tending to be in 5 irregular longitudinal inter-radial series, body wall rods not distinctly C-shaped). We note that the date of publication of species Chiridota rigida by Semper was 1867.

Figures

FIGURE 1. Photos of holotype of Chiridota kermadeca sp. nov. (AIM MA 73394). a, right dorso-lateral view; b, left ventral inter-radial view, insert with photo of 2 radial plates of the calcareous ring of a paratype (AIM MA 73395); c, tentacle crown.

FIGURE 2. SEM images of ossicles and ring plates from paratype of Chiridota kermadeca sp. nov. (AIM MA 73395). a, rod ossicles from tentacle; b, top and middle showing radial plate (left) and inter-radial plate (right) from the calcareous ring, bottom showing inter-radial plate; c, wheels and rod ossicles from dorsal papilla; d, wheels and rod ossicles from ventral papilla.