Comanthus wahlbergii ( Müller, 1843 )

Obuchi, Masami, 2020, Shallow-water Comatulids (Echinodermata: Crinoidea: Comatulida) of the Ashizuri-Uwakai Sea, Shikoku Island, Southern Japan, Species Diversity 25, pp. 309-328 : 313-314

8. Comanthus wahlbergii ( Müller, 1843) [Japanese name: Makieda-koashi-umishida]

Morphology. Centrodorsal thick discoidal, 3.0– 4.1 mm across; polar area flat, 0.7–0.8 times of centrodorsal diameter. Cirri curved inward, XXV–XXXIV, up to 17 segments, 8.5–12.0mm long, arranged in single, partly two rows; c5–7 longest, L/ W 1.7; distal segments laterally compressed, broader than proximal ones, with weak aboral process. Radials invisible. IBr series composed of 2 ossicles, IIBr of mostly 4(3+4) and partly 2, and IIIBr of 4(3+4). Arms usually about 20, up to 37; anterior arms up to 115 mm long, 1.3–2.0 times longer than posterior; brachials short- er than broad, with distal ends everted; 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; segments finely spinose, especially on distal end . Terminal combs present as far as P 8–10 at intervals, consisting of 7–10 segments; teeth paired; primary teeth confluent with lateral margins of pinnule segments, curved inward, basally contacted with adjacent one; small secondary teeth placed closely to primaries; terminal segment with discrete tooth; proximal segment with transverse saucer-shaped tooth. Disk three to four times as wide as centrodorsal, with fleshy papillae on anal tube.

Posture. Nocturnal. Dwelling within cracks or crevices, or between stony corals. Anterior arms extended in nighttime, exhibiting multidirectional posture.

Coloration in life. Arms brown, distally light yellow, sometimes with dark mid-aboral line in proximal part; pinnules aborally green-yellow, or black with yellow tips; centrodorsal dark brown, with yellow marking on center.

Distribution. Oki Island, Japan ( Kohtsuka and Kogo 2012) to New Zealand ( Rowe et al. 1986), Samoa ( Rowe et al. 1986) to South Africa (A. M. Clark 1972). Guam ( Kirkendale and Messing 2003).

Remarks. The large centrodorsal with complete rows of cirri enables this species to be distinguished from other congeners. This species is distributed throughout the West Pacific and Indian Ocean, and shows wide morphological variation according to each region ( Rowe et al. 1986). One specimen (BIK-EC-CR0013) had as many as 37 arms, which was greater than any previous records and comparable to the form from South Africa, formerly considered as subspecies C. wahlbergii multiradiata Gislén, 1938 . However, it did not differ from others in other morphological characters.