Chama croceata Lamarck, 1819

Raines, Bret & Huber, Markus, 2012, 3217, Zootaxa 3217, pp. 1-106 : 66

Chama croceata Lamarck, 1819

Figures 34 A–F

Chama croceata Lamarck, 1819: p. 96 .

Chama croceata Lamarck, 1819 — Huber, 2010: p. 282, figs. 10–12.

Chama imbricata Broderip, 1835, p. 304 , pl. 39, fig. 2, non Lamarck, 1801

Chama imbricata Broderip, 1835 — Oliver, 1992: p. 105, pl. 26.

Chama savignyi Jousseaume in Lamy, 1921: p. 238 — Huber, 2010: p. 676.

Chama plinthota Cox, 1927: p. 98 . (nom. nov.)

Chama plinthota Cox, 1927 — Lamprell & Whitehead, 1992: pl. 24, fig. 152; Brook & Marshall, 1998: p. 213; Spencer et al., 2011: p. 1.

Chama ratoi Boshoff, 1965 p. 151 , pl. 4, fig. 2— Kilburn, 1973: p. 708.

Chama — Luke, 1995: p. 107. (Lot M 1452 in part)

Material examined. Several single valves (up to 47 mm in length) (BK), including valves collected by the 1957/58 Downwind Expedition ( SIO Benthic Collection, M1452), plus specimens from the Marquesas Islands ( MHU).

Diagnosis. Shell medium to large, occasionally subcircular but usually oblong. The LV is the lower attached valve. Specimens are usually dextral with the umbo pointing anteriorward, but occasionally sinistral with the umbo pointing posteriorward. Exterior surface of commarginal lamellose, and typically covered by incrustations. Typical dorsal ridge. Hinge strongly curved with broad folds and deep teeth. Color extremely variable from yellowish brown to greyish purple. In fresh specimens with the typical vertical or radial dark brown to orange marks below the dorsal ridge, continuing on the lower valve. Margins smooth.

Remarks. Some of the worn Chama material identified by Luke (1995) from the SIO Benthic Collection, M1452 ( Figs. 34 C–F) approaches the shape and ridge, but a firm identification is obviously impossible.

Chama croceata is often erroneously referred to as the preoccupied C. imbricata Broderip, 1835 , or its nom. nov. C. plinthota Cox, 1927 , as well as C. ratoi Boshoff, 1965 , described from Mozambique, and C. savignyi Jousseaume in Lamy, 1921, described from the Red Sea. However, all have proved to be consistent with the type material of C. croceata . Huber (2010: 676) clarified C. croceata type locality as the Red Sea.

The 47.3 mm specimen represents the largest bivalve ever found on Easter Island. Elsewhere, C. croceata grows to 100 mm.

Habitat. Occasionally found at several locations around EI, in sand and rubble, from 30–80 m.

Distribution. Chama croceata is known from the Red Sea to the Kermadec Islands, including the Marquesas Islands, Australia, and Norfolk Island, but is not known from the Hawaiian Islands. Easter Island is now considered a range extension— E5.