Acar plicata ( Dillwyn, 1817 )

Raines, Bret & Huber, Markus, 2012, 3217, Zootaxa 3217, pp. 1-106 : 17

Acar plicata ( Dillwyn, 1817)

Figures 7 A–F

Arca plicata Dillwyn, 1817: p. 227 .

Acar plicata ( Dillwyn, 1817) — Preece, 1995: p. 350; Brook & Marshall, 1998: p. 211; Okutani, 2000: p. 849, pl. 422, fig. 18; Tröndlé & Boutet, 2009: p. 4; Huber, 2010: p. 130, fig. 5; Spencer et al., 2011: p. 1; Severns, 2011: p. 432, pl. 197, fig. 6.

Byssoarca divaricata G.B. Sowerby I, 1833: p. 18 .

Acar hawaiensis Dall et al., 1938: p. 14 , pl. 1, figs. 5–8.

Barbatia (Acar) divaricata ( Sowerby, 1833) — Kay, 1979: p. 501, figs. 161 E–G.

Barbatia (Acar) — Luke, 1995: p. 106.

Arca sp. — Trego, 1997: p. 199.

Material examined. Over 100 single valves (6 to 16.1 mm) (BK), including material from the 1957/58 Downwind Expedition ( SIO Benthic Collection, M1442).

Diagnosis. Shell small, elongated trapezoidal, inflated, equivalve, inequilateral, not fragile. Umbones elevated. Posterior end comes to a point at the ventral margin. Exterior surface of pronounced commarginal ridges crossed by radiating ribs. Hinge consisting of numerous teeth continuous under the umbones, slanted, and larger distally. Color creamy white to tan.

Remarks. As usual the EI specimens are quite small, but conform well to Indo-Pacific and Hawaiian material. The Barbatia (Acar) and Arca species noted by Luke (1995) and Trego (1997) from the SIO Benthic Collection, M1442 ( Figs. 7 D–F) represent this species as well.

Habitat. Commonly found at many locations around EI, dead in sand, from 50–150 m.

Distribution. Acar plicata is widely distributed from the Red Sea throughout the Indo-Pacific, to include the Society Islands, Tuamotu Archipelago, Pitcairn Islands, Hawaiian Islands, eastern Australia, Lord Howe Island, Norfolk Island, and the Kermadec Islands. Easter Island is now considered a range extension— E5.