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

Henricia echinata spec. nov.

Figures 42–46

Type locality: Alaska, Aleutian Islands, Andreanof Islands, Adak Island, Bay of Isles (51º 49.023 N, 176º 50.385 W), 13 m. (AKALE 07-0005).

Type material: Holotype, LACM 2007-098.001(leg. R.N. Clark, 1 July, 2007).

Diagnosis: Small, moderately inflated, R to 5.3 cm, R:r 4.8; abactinal skeleton irregular, open meshwork; abactinal plates with 5–11 blunt rather smooth spines; adambulacrals with 8–11 slender, blunt spines, 1 at furrow edge, followed by 2 slightly shorter spines, and 2 irregular rows of 3–4 shorter shorter spines; oral plates with 4–5 marginal and 1 or 2 sub-oral spines; Color in life, red.

Description: Small, moderately inflated, R 5.5 cm, r 1.1 cm, R:r 5.0 cm (Figs. 42 & 43); disc small, rays relatively short, tapering to slender, blunt tips. Abactinal plates forming an irregular, open reticulation (Fig. 44); pseudopaxillae bearing 5–11 short, thick, blunt, smooth spines in two irregular rows; spines to about 0.2 mm long; madreporite small, with irregular spinose ridges; papular area large, with 2–4 papulae per area. Superomarginals about 2–3 times larger than abactinals, and bearing 9–15 spines; intermaginals about half as large as superomarginals, and forming an irregular series extending 35–50% or R; inferomarginals about 1/3 larger than superomarginals, chevron-shaped and bearing 15–21 spines. Actinal iterradial plates less than 1/2 the size of inferomarginal, in a series extending about 75% of R, and bearing 7–12 spines. Adambulacrals (Fig. 45) with a single slender, deep furrow spine, 1 long slender spine at furrow edge backed by 2 similar but somewhat shorter spines, and then 2 rows of 3–4 shorter spines. Oral plates (Fig. 46) with 4–5 long, thick, blunt marginal spines, and 1–2 similar, slightly shorter sub-orals. Color in life uniformly reddish.

Distribution: Alaska, Aleutian Islands, Andreanof Islands, Adak Island, 16 m. Known so far only from the central Aleutians, the Holotype at Adak Island, and an image of a second specimen from Amchitka Island. Further investigation is needed to define the limits of distribution for Henricia echinata, but it may be endemic to the central Aleutians.

Habitat: Rocky substrate with encrusting coralline algae and sponges.

Etymology: From the Latin, for prickly.

Remarks: Henricia echinata is somewhat similar in general appearance to H. asthenactis (Fig. 39), but differs in 1) having the abactinal spines in 2 rows, and lack the thick fleshy membrane; and 2) adambulacrals spines in 2 rows. It bears superficial resemblance to H. rhytisma, but is readily separated by the relatively long, smooth abactinal spines. Henricia echinata also resembles the Arctic-Atlantic Henricia perforata (Müller, 1776), but differs in having much shorter (0.2 mm compared to 0.5–0.7 mm) spines, which are stout and blunt. The spines of H. perforata are slender and pointed (Madsen, 1987).