Cheiraster (Barbadosaster) echinulatus (Perrier 1875)

Cheiraster echinulatus (Perrier)

Archaster echinulatus Perrier, 1876a:268; 1884:263, pl. 10: fig. 4.

Cheiraster echinulatus.–Perrier, 1894:278.–Verrill, 1915:129, pl. 14: figs. 2, 3, pl. 19: fig. 2, pl. 25: fig. 1.

Pectinaster echinulatus.–Ludwig, 1910:449.

This is the smallest of the Atlantic Cheirasters. Its form is more stellate, and the arms more rigid. The dorsal plates are distinctly paxillate, and each bears 8–25 small spinous peripheral granules and a small acute central spine. Each papular area has 3–8 pores at the base of the arms, often not in any particular arrangement, but sometimes, especially in larger specimens, distinctly bilobed. The superomarginal plates (15–26) are large, rectangular, and encroach considerably on the disc, so that the paxillar areas on the arms are quite narrow. Except for the first two interradial plates, they bear a single erect, acute spine, and there may be other small spines around it, especially on the proximal superomarginals. The rest of the plate is clothed in small spinous granules. The inferomarginal plates bear one large spine and up to eight smaller spines on the upper (or lateral) half of the plate, and the lower (or ventral) half is covered with small spinules.

The marginals may be opposite or alternate. The interradial actinal areas have a single row of 6 or 7 round plates, not extending beyond the second inferomarginal. They are covered with small acute spines. The adambulacral plates project strongly into the furrow and bear a palmate series of about ten long furrow spines. On the actinal face of the plate there are usually two large subequal spines and a few small spinules. On each half of the broadly rounded mouth plate are two stout preoral spines and about eight small lateral spines; the actinal face bears one or two large epioral spines and a row of 2–5 smaller spines. The madreporite is of modest size, and deeply grooved with coarse gyri.

This species occurs principally in the Gulf of Mexico, although the Albatross took it also in the West Indies, according to Verrill. Its depth range is from 65–400 fathoms. I do not believe this species gets much over 35 mm (R), and specimens of less than half this size are fully mature.

MATERIAL EXAMINED.–Oregon Station 5913 (1) [R=35 mm, r=8 mm, Rr=1:4]. Alaminos Stations: 11A/68–A–7 (1) [R=10 mm, r=3 mm, Rr=1:3]; 20/65–A–9 (9) [R=16 mm, r=3 mm, Rr=1:4]; 15/65–A–9 (1) [R=25 mm, r=6 mm, Rr=1:4].