Spondylus occidens G.B. Sowerby III, 1903

Raines, Bret & Huber, Markus, 2012, 3217, Zootaxa 3217, pp. 1-106 : 39

Spondylus occidens G.B. Sowerby III, 1903

Figures 19 A–F

Spondylus occidens G.B. Sowerby III, 1903: p. 77 , fig. 9.

Spondylus occidens G.B. Sowerby III, 1903 — Dijkstra & Marshall, 2008: p. 76, figs. 64 C–D, J; Huber, 2010: p. 220, figs. 1–2; Spencer et al., 2011: p. 1.

Spondylus mireilleae Lamprell & Healy, 2001: p. 123 . figs. 4 E–D.

Spondylus mireillae [sic] Lamprell & Healy, 2001 — Raines, 2002: p. 34, fig. 41.

Material examined. Several single valves and fragments (7.3 to 12.4 mm) from EI (BK), plus over one hundred specimens throughout the Indo-Pacific ( MHU), the MNHN type material of Spondylus mireilleae as well as fresh material from New Caledonia ( MHU) .

Diagnosis. Shell small to medium, inflated, thin but not fragile, oblique and somewhat equivalve; auricles relatively small, with the left auricle smaller than the right. Exterior surface sculpture variable consisting of nearly 50 primary radial ribs, which are low and flattened umbonally, and become stronger, raised and ovate with narrow interstices at the margins; some specimens may also have a secondary radial riblet within each interstice; or may have ribs which are ornamented with numerous raised, irregular spines, especially when juvenile. Color from yellow to reddish-brown.

Remarks. This species was first reported as S. mireilleae by Raines (2002), however, Huber (2010: 631) synonymized that species with the widely distributed S. occidens based on type and numerous fresh material studied.

This common species was recently addressed by Dijkstra and Marshall (2008: 76) from Norfolk and Kermadec Islands. Although S. mireilleae was not treated, Lamprell (2006: 96) ’s former synonymy of S. jamarci Okutani, 1983 , was resolved by differences in ribbing. However, the numerous S. occidens studied by the junior author throughout the Indo-Pacific demonstrated not only a high variability in ribbing, but also in color which supported instead Lamprell’s synonymy. In the end, only broad genetic data can reliably resolve spondylids.

Habitat. Occasionally found at several locations around EI, in sand and rubble, from 30–50 m.

Distribution. Spondylus occidens is a widely distributed species, which has been recorded from eastern Africa to the Kermadec Islands, including Saya de Malha Bank, (Indian Ocean, and largest submerged bank in the world), Japan, Indonesia, Vanuatu, New Caledonia, eastern Australia, West Norfolk Ridge, and Easter Island. However, it has not been recorded from the Hawaiian Islands— E5.