Acodontaster hodgsoni ( Bell, 1908 )

Mah, Christopher L., 2023, New Genera, Species, and observations on the biology of Antarctic Valvatida (Asteroidea), Zootaxa 5310 (1), pp. 1-88 : 40

Acodontaster hodgsoni ( Bell, 1908)

FIGURE 12A – G

Heuresaster hodgsoni, Bell, 1908: 8 .

Acodontaster hodgsoni, Fisher 1940: 115 ; A.M. Clark 1962: 20; H.E.S. Clark 1963: 38.

Diagnosis

Body stellate, R/r=2.3–3.3, Arms triangular in cross-section, but also in outline, overall shape elongate, arm tips acutely tapering. Interradial arcs acute ( Fig. 12A, C ). Disk edge distinct, rounded and compressed. Abactinal plates flattened to weakly convex. Surface covered by granules, flattened, quadrate to polygonal, distinctly angular in shape ( Fig. 12D, G ). Granular cover is continuous and obscures boundaries between adjacent plates. Pedicellariae absent from abactinal surface. Marginal plates forming lateral edge, covered by granules identical, if slightly larger than those on abactinal surface, some with small tubercles ( Fig. 12B ). Actinal surface in chevron-like arrangement, but distal plates adjacent to the inferomarginal series obscured by continuous cover of granules ( Fig. 12E ), identical to similar with those on abactinal and marginal plate surface. Proximally, especially around the mouth, plates covered by numerous, small spines, 5–10 centrally, 15 around the edge. Most central spines conical, pointed, widely spaced. Spine height variable with tallest spines 2–3× the height of others. Simple fasciculate pedicellariae present on adambulacral plates adjacent to the mouth, but otherwise no pedicellariae on actinal surface. Furrow spines 2–5, subambulacral spines 2–3. Furrow and subambulacral spines elongate, thickened, remaining subambulacral spines, 3–6, short, approximately 25% of subambulacral spine height, some forming fasciculate pedicellariae. Oral plates each with a single, stout distal-pointing hyaline spine with two shorter, flanking spines ( Fig. 12F ), furrow spines 7–8, suboral spines 7 to 8 ( Fig. 12G ).

Color in life orange to white.

Comments

A single specimen of this species from 2350 m was examined. A.M. Clark (1962) reported a depth occurrence between 4 to 457 m [540 m for A. hodgsoni stellatus ( Koehler, 1920) ], making this an exceptional occurrence. Unfortunately, only a single specimen was recovered. It is hoped that further specimens will close the large disparity in depth for although plausible, the discontinuity between the known and this new occurrence requires additional verification.

Occurrence

Enderby Land eastwards to the Ross Sea and from South Georgia to Queen Mary Land. 4–457m (540 m). New Depth Occurrence: 2350 m.

Material Examined

USNM 1082873, Southern Ocean, Antarctica, −74.1, −175.025, 2350 m. Coll. R/V Eltanin, 8 Feb. 1968. 1 dry spec. R=7.7 r=2.3.

Figures

FIGURE 12. Acodontaster hodgsoni USNM 1082873. A. Abactinal surface. Inset shows granule cover on abactinal plates. B. Close up of abactinal and marginal plate surface. C. Actinal surface. D. Closeup of abactinal and marginal plates cleared of granules. E. Closeup of actinal surface showing granule covered surface furrow spines. F. Recurved hyaline spines around mouth. G. Actinal surface showing cleared plates and furrow spination.