Henricia gemma Clark & Jewett, 2010, spec. nov.

Henricia gemma spec. nov.

Figures 47–52

Henricia sanguinolenta eschrichtii (Müller & Troschel), Fisher, 1911: 276 (pars), non Echinaster eschrichtii Müller & Troschel, 1842: 25.

Type locality: Alaska, Aleutian Islands, Andreanof Islands, Adak Island, Kuluk Bay, Gannet Rocks (51º 52.215 N, 176º 36.383 E), 16 m. (AKALE 07-A0014).

Type material: Holotype, LACM 2007-100.001 (leg. H. Chenelot, 12 July, 2007); Paratype, USNM 1125121 Alaska, Aleutian Islands, Rat Islands, Rat Island (51º 49.288 N, 178º 07.256 E), 14 m (leg. R.N. Clark, 1 July, 2007) (AKALE 07-A0031).

Diagnosis: Small, inflated, R to 3.4 cm; disc large, rays relatively short, thick at base, tapering sharply to a slender tip; abactinal plates small, tightly spaces, bearing 6–18 thorny spinules; adambulacrals with 4–5 large, thick, blunt spines near furrow edge (arranged 1+2-3+2), followed by 10-16 much finer spines in 3 irregular rows. Oral plates with 5 thick marginal and 10–15 similar sub-marginal spines. Color in life uniformly red or yellow.

Description: Small, inflated, R to 3.4 cm (Holotype), r to 1.1 cm, R:r 3–4.3 (Figs 47 & 48); disc broad, inflated, rays short, thick at base, tapering sharply to slender tips. Abactinal plates small, forming a tight reticulation (Fig. 49); pseudopaxillae round to elliptical, bearing 11–32 thorn-tipped spinules; papular areas small, with 1 sometimes 2 papulae per area; madreporite small, located about half way between anus and disc margin, and bearing irregular sub-radial rows of spines. Supreromarginals 2 to 4 times as large as abactinal plates; intermarginal in 2 small, irregular rows, extending about 1/4 of R; inferomarginals about 1/3 larger than superomarginals, and bearing 23–26 spinules. Actinal inter-radial plates about 1/3 or less the size of inferomarginals, extending about 75% of R, a second, smaller series extends only to near the disc margin. Adambulacrals (Fig. 50) with 15–19 spines, a single fairly slender, bunt spine deep in furrow; 1 large thick, blunt spine at edge of furrow with 2 similar spines behind, followed by 2 similar, slightly shorter spines, behind which are 10–14 much shorter, more slender spines (about 1/2 as long) in 3 irregular rows. Oral plates (Fig. 51) with 5 fairly long, stout, blunt marginal spines and 10–16 similar, shorter sub-oral spines, grading shorter aborally. Color in life (Fig. 52) uniform, bright red-orange or yellow.

Distribution: Alaska, Aleutian Islands, Andreanof and Rat Islands, 12– 16 m. Although presently known only from the central Aleutians, because of its similarity to Henricia tumida, further investigation is needed to determine if H. gemma is endemic to this region or is more wide spread in the Aleutians.

Habitat: Subtidal boulders and bedrock, typically on substrate with encrusting coralline algae and sponges.

Etymology: Name is from the Latin, for jewel, in reference to the color of the live animals.

Remarks: Henricia gemma is superficially very similar to H. tumida, with which it shares the same habitat, but may be distinguished by 1) the sharply tapering rays, and 2) much more numerous adambulacral spines, 16–19 versus 6–9 in H. tumida. This species may be wide spread in the Aleutians, but is undoubtedly overlooked because of its similarity to H. tumida. It also bears some resemblance to H. arctica Verrill, 1914, but differs in 1) longer rays which taper sharply to slender tips, those of H. arctica are very short and stubby; 2) more numerous abactinal spinelets, 11–32+ versus 10–15; 3) fewer adambulacral spines, 15–19 grading smaller distally, compared to "several rows of 5–8 spines" (20–32+ in 4 or 5 rows?).