Ophiacantha 2780

F 144772 (holotype), 144774, 146359, 144773, 144770, 82560, 82562, 93272, 82565, 82564.

Family - Ophiacanthidae.

Description

The disc is flat, 6 mm diameter. The radial shields are covered or triangular with rounded corners, separated and parallel to one another, with 2–4 plates between them; 0.5–1 mm long, 1–3 times long as wide, and length 0.1–0.2 times d.d. The dorsal surface is covered by plates, bearing spines/granules, with a visible diameter of 0.3–0.5 mm, overlapping, and 20 plates from the centre to the disc margin (difficult to distinguish plates beneath spines); primary plates not visible. Disc spines or granules of one type, cylindrical or conical, with multiple, more than 3, terminal points/thorns, and glassy transparent shaft. The spines are up to 0.1–0.2 mm long, and 1.5–2 times high as wide; densely distributed (9 per sq mm), covering the radial shields (partially or fully).

The ventral interradial surface is plated, with spines/granules also covering the surface. The oral shields are exposed, teardrop or diamond, wider than long. The adoral shields are exposed, extending to lateral edge of oral shield, separated radially, meeting interradially. Bursal slits extend from the oral shield to the disc margin, not bordered by spines or papillae. The jaw is wider than long, with one, pointed or tapering apical papilla, longer than wide, with thorns. Oral papillae separated by a gap from apical papillae, pointed, thorned. The oral tentacle pore is located inside the jaw (at top of jaw edge), with distal oral papilla similar to other oral papillae.

The specimen has five arms, unbranched, basally constricted, 3–5 times d.d., longest approximately 20–30 mm long, 2 mm wide at the base tapering to the tip. Dorsal arm plates, separated, without spines/granules (sometimes a few spines, 4–5 at the base of arms); fan-shaped, 0.4–0.5 mm long, and 0.7–1 times long as wide. The first ventral arm plates are contiguous with the second plate, diamond or pentagonal, 0.3–0.5 mm long, and 0.8–1 times long as wide. The second ventral arm plates are separated from the third plate, fan-shaped, notched or concave laterally, 0.4–0.5 mm long, and 0.6–0.7 times long as wide. Ventral arm plates of the first free segments separated, heptagonal or hexagonal, 0.3–0.5 mm long, and 0.6–0.9 times long as wide. The lateral arm plates touch one another laterally, or meet on the dorsal and ventral midlines. Tentacle pores along the arm, with one scale, covering the pore, pointed. There are 3 arm spines on the first ventral segment, 5 on the first free segments. The spines are erect, extending around to the dorsal surface, longest dorsally, 2–3 mm long, 12–18 times long as wide, and 2–3 times as long as one arm segment, pointed, cylindrical. There are thorns, in longitudinal series on the surface from the base to the tip of the spine, all along the spine, glassy transparent shaft. Distal ventral arm spines with a prominent longitudinal series of thorns on one side; spines also ventral spine specialised.

Description exported from Delta key and to be finalised when DNA sampling completed. Note species description and image characters may vary slightly in animals of different size within the same species.

Cite this publication as: "T O'Hara (2010). ‘Ophiuroids from deep sea southern Australia. Museum Victoria. Version: 1.0 http://www.museumvictoria.com.au/stars"
Information updated 5 February 2010

MUSEUMVICTORIA