Henricia rhytisma, 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 : 15-17

Henricia rhytisma sp. nov.

Figures 33–38

Henricia sp. C, Clark, 2007. www.jaxshells.org/ henricia 2.htm

Type locality: Alaska, Aleutian Islands, Little Sitkin Island, near Finger Point (51° 58.201 N, 178° 27.184 E), 11 m. ( AKALE 07-0045).

Type material: Holotype, LACM 2007-101.001; Paratype, USNM 1125122. Both specimens from the type locality (leg. Reid Brewer, July, 2007; scuba 11 m)

Material examined: 1, Avatanak Island (54º 05.188 N, 165º 22.839 W) (leg. R.N. Clark, 12 June, 2008; scuba 6 m); 4, Tahoma Bank, SSE of Buldir Island (52º 12.141 N, 176º 12.69 E; NMFS 143- 200401 -158) (leg. R.N. Clark, 14 July, 2004; trawled, R/V Sea Storm, 91 m)

Diagnosis: moderately large, robust, fairly rigid, R to 8.0 cm (Holotype R = 7.9 cm), R:r 5; disc broad, thick, ray thick, inflated at base, tapering to slender tips; abactinal plates with 8–30 short, thick thorny spinelets; adambulacral plates with 8 to 10 thick blunt spines, 1 or 2 at furrow edge largest and usually slightly compressed. Color in life mottled, maroon on tan, cream, orange, yellow or lavender.

Description: Moderately large, robust, relatively rigid, R to 8.0 cm, r to 1.6 mm, R:r 5 ( Figs. 33 & 34); disc broad, thick, rays inflated at base, sharply tapering to slender tips; abactinal plates ( Fig. 35), thick, about as broad as papular areas and crowned with up to 25–30 short, stout, thorn tipped-spinelets, forming a fairly rigid, open, irregular reticulation; papular areas with one to three papulae per area; madreporite small, inconspicous, somewhat closer to anus than disc margin, with subradiating, spinose ridges. Marginal plates larger than abactinal plates, but rather inconspicuous, superomarginals alternating with a series of small, intermarginals to about mid ray, second series of intermarginals extending about 75% of R, inferomarginals large, but inconspicuous, basal series of small actinal interradials often coalescing with them, a primary series of actinal interradials extends along distal to the adambulacrals, to about 3/4 of R; adambulacrals ( Fig. 36) with one deep furrow spine, one or two large, thick, blunt, often compressed spine at edge of furrow, backed by two slightly smaller, similar spines, and four to six smaller, blunt spines in two series or a single staggered series. Oral plates ( Fig. 37) with four or five short, thick, blunt marginal spines and one to four very short, thick suboral spines. Color in life ( Fig. 38), variable, cream, orange, yellow or lavender with a few patched of dark red-brown or maroon abactinally, uniformly pale yellow or cream orally.

Distribution: Alaska, Aleutian Islands, Fox Islands, Avatanak Island (54º 05.188 N, 165º 22.839 W) (leg. R.N. Clark, 12 June, 2008; scuba 6 m) to Tahoma Bank, SSE of Buldir Island (52º 12.141 N, 176º 12.69 E; NMFS 143- 200401 -158) (leg. R.N. Clark, 14 July, 2004; trawled, R/V Sea Storm, 91 m) at depths of 6–91 m with a water temperature of 4.2–5ºC. Henricia rhytisma appears to be endemic to the Aleutian Islands.

Habitat: Subtidal on boulders and bedrock, in areas with high concentrations of sponges, and a moderate current. Frequent in kelp beds [ Eualaria (Alaria) fistulosa , and Nereocystis luetkeana ] in shallow water (<20 m). On rocky substrates in deeper water.

Etymology: From the Greek noun, for patch, in reference to the aboral color pattern.

Remarks: Henricia rhytisma resembles both Henricia asthenactis Fisher, 1910 ( Fig. 39 ) and Henricia aspera Fisher, 1906 ( Fig. 40), with which it co-occurs, all three species having an open reticulation and few adambulacral spines, however the number of the spines, shorter, thicker rays and distinctive coloration distinguish it. The aboral spines of H. asthenactis are relatively long, stout, and sheathed with thick fleshy skin; those of H. aspera are low, stout and unsheathed. Additionally the spines of both of the latter species occur in a single row. The abactinal coloration of H. asthenactis is solid purple, and H. aspera , is uniformly pale orange, cream or purple.

Morphologically H. rhytisma is very similar to the Arctic-circum-boreal H. oculata ( Fig. 41 ), but differs in having 1) more numerous abactinal pseudopaxillar spinelets, 25–30+ compared to 20 (very rarely to 25) in H. oculata ; and 2) more numerous adambulacral spines, 1–2 (at furrow edge)+ 2+ 4–6 in two rows or a single staggered row, compared to 1+ 3–5 in a single irregular row.

Figures

FIGURE 39. Henricia asthenactis, live animal, S of Atka Island (51 º 51.467 N, 174 º 09.4 W) (NMFS 94 - 0201 - 151) trawled R / V Vesteraalen, 152 m (leg. R. Clark, 10 June, 2002). Bar = 5.0 cm.

FIGURE 41. Henricia oculata, live, in situ, Akun Island, 11 m (image: R. N. Clark, June, 2008). FIGURES 42 – 46. Henricia echinata, Holotype, LACM 2007 - 098.001. Fig. 42, Ray, abactinal view. Bar = 1.0 cm. Fig. 43, Ray, actinal view. Bar = 1.0 cm. Fig. 44, Close-up, abactinal surface. Bar = 1.0 mm. Fig. 45, Adambulacral region. Bar = 2.0 mm. Fig. 46, Oral region. Bar = 2.0 mm.