Capillaster AH Clark, 1909e

Table 1; Figs. 5–6

Type species. Actinometra sentosa Carpenter, 1888.

Other included taxa (7). Actinometra macrobrachius Hartlaub, 1890; Capillaster asterias AH Clark, 1931; Capillaster gracilicirra AH Clark, 1912a; Asterias multiradiata Linnaeus, 1758; Capillaster squarrosus Messing, 2003; Capillaster tenuicirra AH Clark, 1912a; Comatula mariae AH Clark, 1907b.

Diagnosis. Mouth excentric in fully developed individuals; up to 110 arms; IBr2 series united by synarthry; first syzygy at 3+4 on arms arising from IBr; IIBr 2 or 4(3+4); IIIBr and beyond 3(2+3); arms arising from IIBr and beyond with first syzygy at 2+3 and first pinnule on br1; distal intersyzygial interval 4–27; distalmost pinnule comb on P3–P21 (in C. tenuicirrus at intervals as far as mid-arm); comb teeth single, triangular, confluent with outer edge of pinnule; comb not tapering significantly distally, or tapering to a blunt tip (in C. gracilicirrus).

Molecular results. Specimens identified as Capillaster sentosus and C. gracilicirrus and those identified as C. multiradiatus, C. squarrosus, C. tenuicirrus, and C. macrobrachius formed two monophyletic groups in both the parsimony and likelihood analyses (Fig. 6), with a minimum of 5.3% uncorrected COI distance between the clades. Intra specific divergence among specimens identified as C. sentosus and C. gracilicirrus (here referred to as C. sentosus) was less than 1.5%. Specimens within the Capillaster multiradiatus clade (identified as C. multiradiatus, C. squarrosus, C. tenuicirrus, and C. macrobrachius) showed an intra specific divergence of up to 7.3% uncorrected COI distance (n=20). A clear separation in intra type versus inter type COI uncorrected distances was not recovered. Therefore, although this clade may represent multiple different species, we currently do not have molecular or morphological data allowing us to clearly distinguish species.

Distribution. Tropical Indo-western Pacific from northern Australia (Fremantle, WA, to Lady Musgrave Is., QLD), west to East Africa and the Red Sea, east to New Caledonia and Vanuatu, and north to East China Sea west of Amami-Oshima, Japan, and Chuuk Atoll (AH Clark 1931; Rowe & Gates 1995; Messing 1998b; Meyer 1986; Kogo 1998). Depth range: 0–118 (?292) m. Except for C. tenuicirrus (82–118 m), the great majority of records are from shallower than 50 m. A few records from greater than 150 m are likely errors.

Remarks. Capillaster is the only Indo-western Pacific genus with IIIBr and following brachiataxes of 3(2+3) and the first syzygy at 2+3 on free arms arising from IIBr and more distal brachitaxes, a trait shared with western Atlantic Davidaster and Nemaster species. Trawled specimens in the collection at LIPI were attributed to Capillaster cf. gracilicirrus and C. cf. macrobrachius, and specimens dredged at Singapore were attributed to C. cf. tenuicirrus (Messing & Tay 2016), all on morphological grounds. As with Comatula and several other confamilial genera, species-level distinguishing features are often size- and proportion-related, reflecting possible oversplitting of the genus. The LIPI and Singapore specimens are assigned here to either C. sentosus or C. multiradiatus (Fig. 6).

NEOCOMATELLINI Summers, Messing & Rouse 2014