Breviturma longispina (H. L. Clark 1917)

Ophiocoma longispina H. L. Clark

Ophiocoma insularia var. longispina H. L. Clark, 1917, p. 441.

Ophiocoma brevipes var. longispina H. L. Clark, 1921, p. 131.

Ophiocoma insularia longispina H. L. Clark: Downey, 1969, p. 104.

MATERIAL EXAMINED.—Easter Island: USNM E647 (type, Shore, 21 December 1904, Albatross collection); BPBM, no numbers (3: two specimens from west coast, between Hanga Roa and Hanga Piko, tidepool, 0–2 feet, 25 January 1969, and a specimen having no specified locality, both collected by J. E. Randall). Pitcairn Island: BPBM, no number (1, Sta. PIT VIII, off south coast, coral bottom, 20–25 fathoms, dredge haul 4, 20 October 1967, collected by D. M. Devaney).

DIAGNOSIS (based on specimens having disc diameters of 9–12 mm).—Arm spines long, tapering; sequence: 3-3-4-4(or 5)-4(or 5)-5-5-5-5-5, and four spines as far as segments 29 or 32, decreasing to three spines on distal segments. Upper arm spines longest, 4 to 6 mm, equal to length of four segments (Figure 32). Arm four to five times disc diameter in length. Disc granules small, rounded, closely packed, covering radial shields and extending some distance into interradial region. Upper arm plates broadly rounded and widest distally, inwardly tapering proximally, fanshaped, slightly broader than long in proximal part of arm, becoming longer than broad on distal segments (Figure 28). Lower arm plates in proximal part of arm broader than long, distal border rounded medially (although sometimes with slight central concavity) with moderately acute lateral edges and incurved sides directed toward proximal edge (Figure 35). Tentacle scales two, of about equal length, outer widest, both tapering toward tip (Figure 35). Oral shields longer than broad, ovate. Adoral shields triangular, with widest angle proximally directed (Figure 33). Usually four oral papillae, outer broadest, overlying part of buccal tentacle scale (Figure 33). One to four additional papillae above (oral to) jaw apex. Five to ten dental papillae. Teeth, three or four each jaw, narrow with hylinated tips. Dental plate 2.4 to 2.9 times longer than broad; septa dividing teeth foramina wide and flat; dental papillae region widened, occupying about one third of total length (Figures 25, 34). Oral plates (jaws) : abradial muscle surface with evidence of shallow ridges and grooves, outer margin interrupted (Figure 30); adradial muscle surface J-shaped (Figure 31). Pigmentation: blackish-brown in alcohol, only slightly darker above than below; borders of oral shields and dental and oral papillae whitish.

Size range examined: disc diameter, 9 to 14 mm; arm length, 45 to 60 mm.