Echinaster sentus

Echinaster sentus (Say)

Asterias sentus Say, 1825:143.

Othilia aculeata Gray, 1840:281; 1866:12.

Echinaster spinosus [part] Muller and Troschel, 1842:22.–Verrill, 1867:343,–Ives, 1890:325.–H. L. Clark, 1898a:6.

Othilia spinosa.–A. Agassiz, 1869:308.

Echinaster sentus.–Lutken, 1871:60 [284].–Perrier, 1875a: 366.–A. Agassiz, 1877:97, pl. 10: figs. 1–6.–Rathbun, 1879: 147.–Verrill, 1915:36, pl. 29: fig. 2.–Tommasi, 1970:17, figs. 46–48.

The small disc and five thick, stumpy arms of this species are distinctive. The rows of plates are: carinal, adradial, superomarginal, inferomarginal, and adambulacral. Each plate bears a large cqnical acute spine, and many plates, particularly the secondaries (which lack a spine), bear a small round flat patch of glassy tubercles. The papular areas are large and the papulae numerous, less numerous on the actinal surface. The adambulacral plates bear one or two slender spines within the furrow, and one or two heavier, subacute spines, one behind the other, on the marginal and actinal surfaces.

The mouth plate bears a heavy, blunt apical spine, 2 or 3 smaller marginal spines, and a small acute suboral spine. The adambulacral marginal spines are webbed together longitudinally. The madreporite is small, round, with radiating gyri, and small spinules. Scattered over the entire dorsal surface, not confined to the papular areas, are large discrete globules of a dark reddish brown, of unknown nature and function (photoreceptive pigment spots ?).

This species is widely distributed from North Carolina to Brazil, in shallow water.

MATERIAL EXAMINED.—Oregon Stations: 1936 (2) [R=62 mm, r=15 mm, Rr=1:4]; 1937 (3) [R=70 mm, r=20 mm, Rr=1:3.5]; 1938 (3) [R=67 mm, r=16 mm, Rr=1:4]; 1934 (5) [R=75 mm, r=18 mm, Rr=1:4].