Clarkcomanthus albinotus, Rowe, Hoggett, Birtles & Vail, 1986

Obuchi, Masami, 2020, Shallow-water Comatulids (Echinodermata: Crinoidea: Comatulida) of the Ashizuri-Uwakai Sea, Shikoku Island, Southern Japan, Species Diversity 25, pp. 309-328 : 315

12. Clarkcomanthus albinotus

Rowe, Hoggett, Birtles, and Vail, 1986 [Japanese name: Fushinaga-kuraaku-umishida]

Morphology. Centrodorsal thin, pentagonal, 2.8–3.4 mm across, at almost same level of radial; polar area 0.7–0.8 times of centrodorsal diameter; subradial clefts distinct. No functional cirri, but for few cirrus scars. Radials exposed, length 18–30% of centrodorsal diameter. IBr series composed of 2 ossicles, IIBr of 2 or 4(3+4), and IIIBr of 4(3+4); each ray well separated. Arms 28–31; anterior arms up to 170 mm long, 1.5–1.9 times longer than posterior; first arm syzygy at br 3+4; distal intersyzygial intervals 4. Comparative pinnule length PD > P 1 >>P 2 =P 3 =P 4 =P 5; PD and P 1 enlarged, with longest segments L/ W 1.2; distal pinnules long, almost same length as P 1; segments of pinnules beyond P 3 finely spinose, with distal-oral edge projected like spine . Terminal combs present to P 2, consisting of 6–10 segments; tooth paired; primary tooth confluent with lateral margin, straight, widely spaced from adjacent one; secondary tooth smaller but distinct; terminal and proximal segments diminished tooth. Disk three to five times as wide as centrodorsal.

Posture. Dwelling within cracks or crevices, or between stony corals, with anterior arms in multidirectional posture.

Coloration in life. Arms yellow to dark brown, sometimes whitish at distal half, with pale mid-aboral line on proximal part; pinnules aborally striped with yellow and black, often with red tips.

Distribution. Kii Peninsula, Japan ( Kogo and Fujita 2014) to southern Queensland, Australia ( Rowe et al. 1986).

Remarks. Genus Clarkcomanthus is characterized by the first arm syzygy at br 3+4, reduced centrodorsal with few cirri, and the terminal combs with small teeth confluent or not. The examined specimens were identified by restricted distribution of the terminal combs, the presence of secondary teeth on the combs, and some segments of proximal pinnules longer than wide.