Henricia gemma, Clark, Roger N. & Jewett, Stephen C., 2010

Clark, Roger N. & Jewett, Stephen C., 2010, A new genus and thirteen new species of sea stars (Asteroidea: Echinasteridae) from the Aleutian Island Archipelago, Zootaxa 2571, pp. 1-36 : 19-20

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?).

Figures

FIGURES 47 – 52. Henricia gemma, Holotype, LACM 2007 - 100.001. Fig. 47, Whole animal, Abactinal view. Bar = 1.0 cm. Fig. 48, Whole animal, actinal view. Bar = 1.0 cm. Fig. 49, Close-up, abactinal surface. Bar = 1.0 mm. Fig. 50, Adambulacral region. Bar = 1.0 mm. Fig. 51, Oral region. Bar = 4.0 mm. Fig. 52, Holotype, live, in situ. R = 5 cm.