Comanthus gisleni Rowe, Hoggett, Birtles, and 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 : 312-313

5. Comanthus gisleni Rowe, Hoggett, Birtles, and Vail, 1986 [Japanese name: Gisuren-umishida]

Morphology. Centrodorsal thin, slightly raised from level of radials, 2.0–4.0 mm across; polar area flat, 0.7–0.8 times of centrodorsal diameter. Cirri weak, VII–XIII, up to 14 segments, 8.0 mm long, arranged in single row with gaps; c4–7 longest, L/W usually 1.2, up to 1.8; distal 4–5 segments with aboral transverse ridge. Radials narrowly exposed, length less than 15% of centrodorsal diameter. IBr series composed of 2 ossicles, and II–IIIBr of mostly 4(3+4), rarely 2. Arms up to 29; anterior arms up to 155 mm long, 2.1–2.4 times longer than posterior ones; brachials shorter 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; middle segments of distal pinnules with fringing spines on distal end. Terminal combs present to near arm tip at intervals, consisting of 7–14 segments; teeth single, confluent with lateral margins of pinnule segments, curved inward, basally contacted with adjacent one; terminal segment with discrete large tooth; proximal segment with transverse saucer-shaped tooth. Disk five to six times as wide as centrodorsal.

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

Coloration in life. Uniformly black with orange pinnule tips. Sometimes the aboral side of arms is cream.

Distribution. Nii-Jima Island, northern Izu Islands, Japan ( Kogo 1998) to Great Barrier Reef ( Rowe et al. 1986).

Remarks. This species is closely similar to C. parvicirrus , and distinguished mainly by the presence of the spines fringing the distal ends of the segments of the distal pinnules. Morphologies of examined specimens were mostly consistent with the original description, but the coloration was different. The dark mid-longitudinal line on arms constantly observed in Australian specimens was absent from those examined here.