Sclerasterias contorta (Perrier 1881)

Sclerasterias contorta (Perrier)

Asterias contorta Perrier, 1881a:1.

Asterias angulosa Perrier [non Muller], 1881a:3; 1884:202.

Orthasterias contorta.–Verrill, 1914:48; 1915:18.

Orthasterias (Stylasterias) subangulosa Verrill, 1914:168, 370. Orthasterias subangulosa.–Verrill, 1915:16, pl. 2: figs. 1, 2, pl. 9: figs. 1, 1a.

Eustolasterias subangulosa.–Fisher, 1923:255.

Eustolasterias contorta.–Fisher, 1923:255.

Sclerasterias subangulosa.–Fisher, 1928a:107, 108.

Sclerasterias contorta.–Fisher, 1928a: 107, 108.

This species has a small disc and five long, narrow arms, angular and straight sided, tapering to an acute point. The disc dorsum has an irregular pentagon of plates, each bearing one or two spines. The carinal plates on the arm form a prominent ridge; they are lobed and bear a single, large, aciculate spine surrounded by a dense wreath of small, blunt, crossed pedicellariae. They connect by a series of elongate ossicles to the prominent superomarginal plates. There is an incomplete series of dorsolaterals, many without spines. Every other superomarginal bears a spine similar to those of the carinals on the abactinal portion of the plate, and each plate may bear, on the abactinal portion, a large round patch of low glassy tubercles. These usually tend to become fewer and smaller with growth. A long lobe on the superomarginal connects it to the corresponding inferomarginal, leaving a wide, bare space, devoid of spines or other ornamentation, between the two series of plates.

The inferomarginal plates bear two spines; those of the outer (or abactinal) series are webbed together and bear, on the abactinal side, a dense patch of pedicellariae similar to those wreathing the upper spines. The inner (or actinal) series of inferomarginal spines are free and without pedicellariae. There is a single row of broad, low actinal plates between the inferomarginals and the adambulacral plates. Between the actinals is a single papula; elsewhere, above the inferomarginals, the papulae occur usually in pairs between the plates, but there may be as many as 5 or 6 in each area. The adambulacral plates bear two long, slender, divergent spines which form a double row down each side of the ambulacral groove. The groove is wide, and the tube feet are in four rows. The small, narrow mouth plates project into the peristome and bear an apical, forward-directed spine and a smaller oblique marginal spine on each half; there are two sets of suboral spines, the first of one spine and the next of two. Large, isolated, lanceolate pedicellariae occur here and there on both surfaces, mostly on or near the disc. The madreporite is of moderate size, irregularly round, and plane to concave.

This species differs from S. tanneri, which occurs from Cape Hatteras north, in having a more prominent carinal ridge, an incomplete row of dorsolaterals, fewer large lanceolate pedicellariae, and one or two spines on the dorsal disc plates, instead of a number of small spines, as well as in having angular, straight-sided arms, pentagonal in cross section (the arms of S. tanneri are almost round in cross section).

This species has previously been recorded from Florida to Barbados in 11–188 fathoms.

MATERIAL EXAMINED.–Oregon Station 4731 (1) [R=90 mm, r=9 mm, Rr=1:10].

Asterias Linnaeus

Asterias Linnaeus, 1758:661. [Type, by subsequent designation, A. rubens Linnaeus (Norman, 1865:126).]

Stellonia Nardo, 1834:716. [Type, by subsequent designation, Asterias rubens Linnaeus (Fisher, 1913:639).]

Uraster L. Agassiz, 1835a:191. [Nomen nov. for Stellonia Nardo.]

Asteracanthion Muller and Troschel, 1840:102. [Type, by original designation, Asterias rubens Linnaeus.]

Atlasterias Verrill, 1909:65. [Type, by original designation, A. rathbuni Verrill.]

Parasterias Verrill, 1914:53. [Type, by original designation, P. albertensis Verrill.]

Large disc; five or six broad, rather short arms; aboral skeleton forms an open network, with spines in nearly regular series on carinal and marginal plates, but irregular elsewhere.

Only one species is known from the Gulf and Caribbean.