Davidaster Hoggett & Rowe, 1986

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, Zootaxa 4268 (2), pp. 151-190 : 160

Davidaster Hoggett & Rowe, 1986

Table 1, Fig. 2

Type species. Antedon rubiginosa Pourtalès, 1869 .

Other included taxa (1). Actinometra discoidea Carpenter, 1888 .

Description. Mouth excentric in fully developed individuals; up to 35 (possibly 43) arms; centrodorsal welldeveloped, circular, and with cirri; IBr2 series united by synarthry; first syzygy at 3+4 on arms arising from IBr; IIBr 4(3+4) (rarely 2 united by synarthry); 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; distalmost pinnule comb on P2–P4; combs tapering to a distal point, composed of paired, equal-sized and transversely oriented teeth.

Distribution. Western Atlantic from the Gulf of Mexico, southern Florida and the Bahamas to Recife, Brazil ( Meyer et al. 1978; Tommasi 1965). Depth range: low intertidal to perhaps 150 m (Messing, unpublished data). Records from depths greater than 200 m (maximum 355 m), all attributed to D. discoideus (AH Clark 1931), are chiefly dredge or trawl collections along steep island margins, where depth could not be accurately assessed. Records of D. rubiginosus are no deeper than 60 m.

Remarks. Davidaster includes two rheophobic species found on shallow western-Atlantic reefs ( Meyer 1973a, b). Their depth ranges overlap, but D. discoideus occurs to substantially greater depths ( Meyer et al. 1978; Messing, unpublished). Both typically extend their longer arms from under corals and ledges in a multidirectional posture ( Meyer & Macurda 1980). Both conceal the centrodorsal, although D. rubiginosus may be almost completely exposed at night, and D. discoideus lives deeper within the reef infrastructure in shallower water ( Macurda & Meyer 1977). Morphological distinctions between the two have not been thoroughly quantified, but relative differences generally distinguish local populations. Davidaster rubiginosus is larger and more robust, with up to at least 35 arms up to 37 cm long, whereas D. discoideus is more slender, with up to 23 arms ( Macurda 1975). Previous descriptions have emphasized a dark aboral arm stripe as diagnostic for D. rubiginosus , although D. discoideus may also have an aboral stripe, and D. rubiginosus may be completely black. In general, however, D. discoideus has darker pinnule tips (see Meyer, 1973a, b, for descriptions of all color varieties). An additional species of Davidaster , sister to D. rubiginosus , and co-occurring with both taxa in the southern Caribbean is currently being described (personal communication, David Meyer). As D. rubiginosus is known to breed between October and March ( Mladenov & Braby, 1987), differences in reproductive timing may permit the co-occurrence of multiple closely-related species.

Figures

FIGURE 2. Maximum likelihood tree of Comatellinae inferred from COI. Symbols near nodes refer to bootstrap (BS) and jackknife (JK) support scores, for maximum likelihood (ML) and maximum parsimony (MP) analyses, respectively. An asterisk indicates nodes with> 90 % bootstrap and jackknife support. Other scores are represented BS / JK. A hyphen is given for nodes not recovered in MP analyses. Previous morphological identifications in brackets. Taxa labeled as: location - Genbank accession number. Location abbreviations — Great Barrier Reef, Australia (GBR); Madang, Papua New Guinea (PNG); Raja Ampat, Indonesia (Raja); Rowley Shoals, Western Australia (WA). New COI sequences: Genbank KR 010271 - KR 010293.