Henricia elachys, 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 : 22-24

Henricia elachys sp. nov.

Figures 59–62 & 64

Type locality: Alaska, Aleutian Islands, Rat Islands, Rat Island (51º 49.594 N, 178º 27.184 E), 14 m. ( AKALE 07-A0031).

Type material: Holotype, LACM 2007-099.001; 1 Paratype, USNM 1125123 (leg. R.N. Clark, 1 July, 2007).

Diagnosis: Small moderately inflated, R to 2.3 cm, R:r 3–3.2; disc relatively broad, rays broad at base, tapering to slender tips; abactinal skeleton fine, open meshwork; pseudopaxillae round or oval, bearing 16–27 very slender spinules with 1–3 apical thorns. Actinal inter-radial series only about 75% or R. Adambulacrals with 10–16 rather slender spines, in 3 rows, 2 long spines at the furrow edge, followed by 2 lateral rows of 3– 5, and a central row of 2–4. Color in life reddish, mottled with lighter colors.

Description: Small, moderately inflated, R to 2.3 cm (Holotype R = 2.1 cm), r to 0.7 cm, R:r 3–3.2 cm ( Figs. 59 & 60 ); disc broad, rays relatively short, broad at base, tapering to slender tips. Abactinal plates small, round to oval, spaced about 1 diameter or so apart, giving a rather open reticulum; pseudopaxillae ( Fig. 61 ) with 16–27 fairly long, even spinules, bearing 1–3 apical thorns; papular areas large, bearing 2–4 papulae each; madreporite small, round, spinose (spines often in broken ridges). Superomarginals twice or less the size of abactinal plates, bearing 12–17 long spinules; intermarginals limited to a few irregular plates at base of rays; inferomarginals less than twice as large as superomarginals, bearing 21–25 slender spinules in 2–3 rows. Adambulacrals ( Fig. 62 ) with 1 fairly long, bent spine deep in furrow, 10–16 fairly long, stout actinal spines in 2 lateral rows of 3–6, and a (usually) partial central row of 2–4, 1–2 at edge of furrow much longer than others. Oral plates ( Fig. 62 ) with 5 thick, bunt or pointed marginal and 6–9 similar sub-oral spines. Color in life (Fig. 64) reddish, often with lighter mottlings on abactinal surface, actinal surface yellow-cream.

Distribution: The three type specimens all were taken at Rat Island, mixed with the similar appearing H. tumida , but it is probably wide spread in the Aleutians.

Habitat: bedrock and boulders encrusted with coralline red algae, various sponges, hydroids and bryozoans.

Etymology: From the Latin, meaning small.

Remarks: This small species was taken mixed with the similar and very variable H. tumida ( Figs. 63), from which it differs in 1) more open abactinal skeleton; 2) very slender abactinal spinules, those of H. tumida are very thick and blunt; 3) much more numerous (10–16) adambulacral spines, which occur in 3 rows in H. elachys , versus a single (often irregular or staggered) row of 4–8 in H. tumida ( Fig. 63); and 4) smaller, more numerous papulae 2–4 per area versus usually 1, rarely 2, large papulae in H. tumida .

Figures

FIGURES 59 – 62. Henricia elachys, Holotype, LACM 2007 - 099.001. Fig. 59, Whole animal, abactinal view. Bar = 1.0 cm. Fig. 60, Whole animal, actinal view. Bar = 1.0 cm. Fig. 61, Close-up, abactinal surface. Bar = 1.0 mm. Fig. 62, Close-up, adambulacral / oral region. Bar = 5.0 mm.