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CARDITIDAE CUNINAE |
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Cuna cuneata (Laseron, 1953) Description: Shell small. Prodissoconch relatively small, dome-shaped, rim thickened. Shape triangular, higher than long, umbo on midline, anterodorsal slope weakly convex, posterodorsal slope weakly concave. Escutcheon wide, lunule narrower. Exterior with 20-21 radial ribs that do not radiate from prodissoconch area but are perpendicular to hinge area, crossed by commarginal growth lines. Interior smooth apart from muscle scars; margin with about 20 denticles. Hinge strong. Ligament internal. Shell opaque white. Size: Up to 2.2 mm in length. Distribution: Known only from Sydney, NSW. Habitat: Known from beach washup and down to 26 m. The AMS collection holds only 4 lots of this species, suggesting it is rare. Comparison: This species is similar to Cuna saza, but the two species differ in the geometry of the rib radiation; in C. saza the ribs radiate from the prodissoconch, while in C. cuneata they are perpendicular to the hinge area, a condition that is unusual for any bivalve. Synonymy: None Fig. 1: Off Long Reef, Collaroy, NSW (C.90562, SYNTYPES). SEM image by Peter Middelfart, Australian Museum. |
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