Paragonaster subtilis (Perrier 1881)

Paragonaster subtilis (Perrier)

Goniopecten subtilis Perrier, 1881a:26; 1884:168, 183, 187, 253–254, pl. 5: figs. 3–4; 1885c:41; 1885a:884.–Sladen, 1889: 726.

Archaster formosus Verrill, 1884:383–384; 1885:519, 543.

Pentagonaster elongatus Perrier, 1885c:38.

Paragonaster cylindratus Sladen, 1889:311, 314–318, 655, 693, 713, 752, pl. 51: figs. 3, 4, pl. 53: figs. 3, 4.–Perrier, 1894:357.–Verrill, 1894:257; 1899:196.

Paragonaster formosus.–Verrill, 1894:257; 1895:137; 1899:196.

Paragonaster elongatus.–Perrier, 1894:35, 357, 362–363, pl. 21: fig. 3, pl. 24: fig. 4.–Verrill, 1899:196.

Paragonaster strictus Perrier, 1894:35, 357, 363–365, pl. 25: fig. 5.–Verrill, 1899:196.

Paragonaster subtilis.–Perrier, 1894:31, 35, 40, 357, 358–362, pl. 23: fig. 5, pl. 24: fig. 3.–Verrill, 1899: p. 196.–Koehler, 1909b:86–87, pl. 4: fig. 2.–Grieg, 1921:20–21.–Mortensen, 1927:79.–Macan, 1938:361.–Madsen, 1951: p. 89.

This stellate species has a relatively small disc and five long, narrow arms. The abactinal plates are paxillate, with a short, stout pedicel and a rounded top bearing large, round, flattened granules centrally and a single row of slender spinelets peripherally. A single row of large, flat, rectangular plates, similarly ornamented, extends out the arms. Papular areas are large, covering most of the disc except a small central and interradial area. There are about eighty-four nearly square superomarginal plates that are mainly in the horizontal plane. They are covered by large, round, flattened granules and are separated medially on the arms by a single row of plates. The inferomarginal plates correspond to the superomarginals and are covered with short, spaced spinules and 6–10 longer lanceolate spines. The actinal areas are small, not extending beyond the third marginal. The plates are covered with short, spaced spinules and some also bear one or two longer lanceolate spines. The pectinate adambulacral plates bear a curved furrow series of 5–8 blunt, cylindrical spines, 1–3 lanceolate spines on the face of the plate, and subambulacral spinules like those of the actinal plates.

The mouth plates are convex and prominent; they are covered with long lanceolate spines, thickly clustered at the apex of the plate and more widely spaced on the actinal face of the plate; the spines ai the apex are quite thorny. The suture between the plates is narrow. The madreporite is small, irregular in shape, and mostly or entirely hidden by the adjoining abactinal plates. It is covered with very coarse deep gyri. The oculars are large, long, oval, and covered with spaced, round granules. There are no pedicellariae. In all of the specimens I have seen, the first pair of tube feet is greatly enlarged and extended toward the mouth. The significance of this feature escapes me.

In the western Atlantic, this species occurs in the Gulf of Mexico and from about 37° to 41° N; it is also known from the Azores, the Cape Verde Islands, and the Bay of Biscay. Its bathymetric range is 2,455–4,375 meters.

MATERIAL EXAMINED.–Alaminos Stations: 29/69-A-13 (5) [R=56 mm, r=12 mm, Rr=1:4.9]; 4A/68-A-7 (1) [R=65 mm, r=13 mm, Rr=1: 5].

Nymphaster Sladen

Nymphaster Sladen, 1885:612. [Nomen nudum.]

Nymphaster Sladen, 1889:294–295. [Type, by subsequent designation, Nymphaster protentus Sladen, 1889 (=Pentagonaster arenatus Perrier, 1881a.–objective synonym). (Fisher, 1917:90).]

Arms long; R/r greater than three; superomarginals contiguous medially throughout length of arm; abactinal plates low-tabulate; adambulacral plates with strongly angular furrow margins, becoming apophyses distally; gonads in single tuft; no internal radiating ossicles.

Two species in this genus occur in the tropical western Atlantic; a third, N. ternalis (Perrier), has been placed in the synonymy of N. arenatus by Halpern (1970a).