Comaster L. Agassiz 1836
Creators: name: Summers, Mindi M.
name: Messing, Charles G.
name: Rouse, Greg W.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Crinoidea
Comatulida
Comasteridae
Comaster

description: Comaster L. Agassiz, 1836
Table 1, Figs. 8–9
Type species. Alecto multifida Müller, 1841.
Other included taxa (2). Actinometra schlegelii Carpenter, 1881; Comaster audax Rowe, Hoggett, Birtles & Vail, 1986.
Diagnosis. Mouth excentric in fully developed individuals; up to 180 arms; centrodorsal small, discoidal or pentagonal; cirri absent or present; aboral surface with irregular plates between bases of adjacent rays; IBr2 united by synarthry; IIBr and beyond 2 or 4(3+4), usually with IIIBr of 2 ossicles exteriorly and 4(3+4) interiorly; first syzygy on undivided arms always 3+4; distal intersyzygial interval 4; distalmost pinnule comb at least P2 (usually P3–P8), sometimes at intervals to P14; combs arising gradually and tapering to a sharp point distally; pinnules on brachitaxes and sometimes P1 with comb of single, nonconfluent teeth; combs on brachial pinnules of paired, confluent, erect, more or less equal-sized and well separated teeth; pairs sometimes joined to form a transverse bar (Fig. 8 D, M). Paired comb teeth may be absent on juvenile specimens (10–13 arms).
Distribution. Tropical Indo-western Pacific from northern Australia (Perth, WA, to Solitary Is., NSW), west to the Maldives, east to Fiji, and north to Sagami Bay, Japan. Depth range: 2– 183 m. All but a very few records are from depths shallower than 50 m.
Molecular results. Specimens identified as Comaster nobilis and C. schlegelii are less than 1.6% divergent in uncorrected distances of COI. As a clade, specimens of nobilis / schlegelii were at least 4% divergent in uncorrected distances of COI from C. audax (Fig. 9). A more comprehensive molecular and morphological analysis of Comaster is in preparation (Owen et. al. in prep.)
Remarks. Species of Comaster are most easily distinguished from other comatulids by the irregular plates between the bases of adjacent rays, which give the aboral surface a solid, paved appearance. Because specimens identifiable as C. nobilis or C. schlegelii exhibit such minimal sequence divergence, we reinstate the former as a junior synonym of the latter, in agreement with AH Clark (1911b, 1911c, 1912b, 1931). Nevertheless, substantial morphological variation exists. Smaller C. schlegelii with numerous cirri are easily distinguished from larger cooccurring “ C. nobilis ” on the Great Barrier Reef. The distinction may be ontogenetic, although accompanied by distinct and consistent color pattern differences. Specimens attributed to “ C. nobilis ” lose cirri with growth. At Raja Ampat, Indonesia, C. schlegelii and “ C. nobilis ” with similar centrodorsal diameters have ~20 versus 1 (plus a few tiny buds) cirri, respectively, whereas a smaller “ C. nobilis ” with the same color pattern as the large specimen has ~20 cirri. Specimens attributed to C. schlegelii from Micronesia, where “ C. nobilis ” has not been collected, retain well-developed cirri, reach a larger size, and perch in the open instead of nestling in crevices as C. schlegelii typically does elsewhere (Messing 1998b).
description: Published as part of Summers, Mindi M., Messing, Charles G. & Rouse, Greg W., 2017, The genera and species of Comatulidae (Comatulida: Crinoidea): taxonomic revisions and a molecular and morphological guide, pp. 151-190 in Zootaxa 4268 (2) on page 171, DOI: 10.11646/zootaxa.4268.2.1, http://zenodo.org/record/580173