Circeaster Koehler 1909

Circeaster Koehler, 1909 Circeaster Koehler, 1909: 83. Halpern 1970a: 265. Downey 1973: 47, 55, pl. 21A, B. Clark & Downey 1992: 237, A.M. Clark 1993: 250; Mah 2006: 927. Diagnosis Body weakly stellate to stellate, R/r> 2.5. Disk strongly arched, large. Arms elongate, tapering. tips upturned. Interradial arcs linear to curved. Abactinal arm plates two to three times larger than disk plates, variably changing between gradually to abruptly from disk to arm. Abactinal arm and disk plates bare. Superomarginal plates abutted over midline in several species. Marginal plates bare, but variably with spinelets or granules present along dorsolateral/ventrolateral edges and surfaces of marginal plates. Greater density of spinelets/granules on inferomarginals than on superomarginals. Pedicellariae uncommon. Adambulacral furrow spines 6–15. Enlarged subambulacral spine or spines present. Prominent, paddle-like, bivalve, or sunken pedicellariae with jagged teeth present on adambulacral plates. Comments Circeaster includes, at present, 9 species distributed throughout the Atlantic, Pacific and Indian Oceans in deep-sea settings, 320–2160 m. A new subfamily, the Circeasterinae was recently established for Circeaster and related genera (Mah 2024) which all share differently sized disk and arm plates, distinctly coarse granules, blocky marginal plates, large subambulacral spine or spines, and alveolar pedicellariae.