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LUCINIDAE |
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Divalucina cumingi (A. Adams & Angas, 1864) Description: A medium-sized and moderately thick lucinid. Shape almost circular plus low umbones, slightly longer than high, umbo on midline. Lunule long and narrow. Anterior dorsal margin slightly concave, posterior dorsal margin straight, other margins smoothly rounded. Exterior with anterior and posterior curved ridges, meeting at anterior quarter. Interior pitted, posterior muscle scar approximately elliptical, anterior long and narrow; pallial line continuous; margin outside pallial line weakly lined. Hinge (Fig. 2) both valves with 2 cardinal teeth, single small anterior lateral and no posterior lateral. Ligament long, external. Shell colour white. Size: Up to 45 mm in length. Distribution: Australia and New Zealand, but see Remarks below. The range is probably from Port Stephens, NSW, southwards and around southern Australia, to south-western WA. Habitat: Known from the shallow subtidal down to 300 m. It lives in sufficiently shallow water to be fairly commonly washed up on beaches. Comparison: The unusual sculpture of two sets of curved ridges distinguishes this species. Remarks: The distribution of this species in eastern Australia is unclear. The Australian Museum holds five lots identified as this species from Queensland, ranging from Mapoon, Cape York, southwards to Heron Island. Proceeding southwards there are then no specimens until Port Stephens, NSW, and then there is a continuous distribution of specimens around southern Australia to South Australia. If these were all the same species it would be a most unusual distribution, as southern Australian species usually do not occur further north than central or northern NSW. Probably the Queensland specimens are of a different species, and the actual northern limit is Port Stephens. Outside Australia, a genetics study is needed to decide on the relationship with specimens from New Zealand. Fig. 1: Kurnell, Botany Bay, NSW (C.075697) Fig. 2: Kurnell, Botany Bay, NSW (C.075697) |
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