Divarilima aff. sydneyensis ( Hedley, 1904 )

Raines, Bret & Huber, Markus, 2012, 3217, Zootaxa 3217, pp. 1-106 : 47-48

Divarilima aff. sydneyensis ( Hedley, 1904)

Figures 23 D–F

Lima sydneyensis Hedley, 1904: p. 200 .

Divarilima sydneyensis ( Hedley, 1904) — Brook & Marshall, 1998: p. 212; Spencer et al., 2011: p. 1. Material examined. More than fifty single valves up to 4.5 mm (BK).

Diagnosis. Shell small, thin, translucent, semicircular, strongly convex. Umbones well elevated and located anteriorly. The lunule is deeply excavated. Dorsal margin straight and relatively short. Anterior margin relatively short and concave along the dorsal area. Exterior of valves completely covered with delicate punctations which are arranged in such a way to form numerous divaricate or zigzag rows. Interior smooth with pallial sinus running from muscle to muscle. Hinge plate very wide and triangular. Color translucent white.

Remarks. Of the six Divarilima species described from the Indo-Pacific, only D. sydneyensis approaches the EI species. Divarilima abscisa ( Barnard, 1964) , from South Africa was excluded based on morphology and biogeography. Equally excluded was D. elegans Hayami & Kase, 1993 , from Okinawa, which is understood to be distinct from D. abscisa . The Japanese Divarilima iwaotakii ( Habe, 1961) , does not match in either biogeography or morphology.

Nothing similar has been recorded from the Hawaiian Islands, and the deeper water fauna of the Marquesas Islands is barely known. Of the described species, the type species D. sydneyensis from Australia appears to be closest to the EI species. On the other hand, Spencer et al. (2009: 198) recorded five Divarilima from New Zealand, of which, four are unnamed. Moreover, D. sydneyensis may be restricted to the Australia region. This complex group needs much more work and more material. At present it can neither be excluded that the EI species is conspecific with a western species, nor that it represents a valid and endemic Divarilima species.

Habitat. Commonly found at many locations around EI, in sand and rubble, from 100–200 m.

Distribution. Unknown at present. The conspecifity with other western species cannot be excluded. However, D. sydneyensis is reliably known from eastern Australia and Norfolk Island only. The records from New Zealand or Kermadec Islands may refer to undescribed species— E5.