Gilbertaster Fisher 1906

Mah, Christopher L., 2023, New Goniasteridae and in situ observations significant to deep-sea coral predation, Memoirs of Museum Victoria 83, pp. 1-35 : 24

Gilbertaster Fisher 1906

Fisher, 1906: 1062; McKnight, 1973: 192; Mah, 1998: 66; H.E.S.

Clark and McKnight, 2001: 49; Mah et al., 2010: 270

Diagnosis. Arms triangular, narrow and tapering. Disk weakly swollen. Thick and pulpy tissue covering abactinal, marginal and actinal plates. Abactinal plates low, polygonal, covered by 1–12 closely articulated angular granules elongate to round in shape, flattened, surface texture smooth to rough. Fasciolar grooves shallow. Secondary plates present. Abactinal plates with angular accessories. Pedicellariae large, bivalved with smooth valves, the length of one to two plates and abundant on abactinal surface. Marginal plates, 50–70 per interradius (arm tip to arm tip), squarish in outline with edges rounded, covered by angular granules similar to those on abactinal surface. Variable surfaces smooth (on Gilbertaster anacanthus ) to roughened (on Gilbertaster caribaea ). Pedicellariae large, bivalve similar to those on abactinal surface on marginal plate surface, many bisecting the width of the plate. Spines absent from superomarginal and inferomarginal plate series. Granules, densely arranged, covering superomarginal and inferomarginal plate series. Superomarginal and inferomarginal plates quadrate at interradius. Fasciolar grooves on marginal and actinal surfaces absent. Fringe of accessories on marginal plates poorly differentiated. Superomarginal plates forming prominent dorsolateral fringe. Actinal plates covered by 1–15 flattened, polygonal, angular granules. Large bivalve pedicellariae similar to those on abactinal and marginal plate surfaces, abundant on actinal plates. Actinal plates with granules but lacking large spines or spinelets. Pedicellariae, bivalved, present on plate series at perpendicular angle, adjacent to ambulacral furrow. Pedicellariae, flat-tong shaped, with serrated blades present on actinal plates. Pedicellariae on raised bases, abundant. Furrow spines two to four (usually three) blunt, thickened spines, horizontally flattened ( G. anacanthus ) to triangular/quadrate in cross-section ( G. caribaea ). Subambulacral spines, 1–4, blunt, flattened. Round to quadrate ( G. anacanthus ) to triangular in cross-section ( G. caribaea ). Pedicellariae, bivalved, enlarged on first adambulacral (similar to others) replacing subambulacral spination and sometimes replacing furrow spination. Subambulacral spines smaller in size, more abundant. Furrow spines round in cross-section.

Comments. Gilbertaster was placed within the Hippasterinae by Mah et al. (2010) and includes two species, the Indo-Pacific G. anacanthus and the tropical Atlantic G. caribaea . Mah (2020) reported on four observations of G. caribaea feeding on primnoid octocorals, identified as Plumarella sp. , consistent with the predatory habits observed in other members of the Hippasterinae.