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MACTRIDAE |
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Mactra jacksonensis E.A. Smith, 1885 Description: Shell small, translucent or opaque. Shape elongate, length greater than height, umbo on or slightly anterior to midline; anterior end broadly rounded, posterior end more pointed; ridge from umbo to postero-ventral margin. Exterior smooth apart from weak commarginal growth lines. Interior white blotched with fawn, sometimes with 3 brown radial rays; usually smooth, pallial lines and muscle scars usually not evident; pallial sinus shallow (Fig. 2). Hinge as for family. Ligament internal. Shell white or fawn externally, brown radial rays sometimes visible externally but usually more obvious internally. Size: Up to 14 mm in length. Distribution: Endemic to Australia: Caloundra, Qld, southwards and around southern Australia, to southwestern WA, including Tas. Habitat: Lives in sand in the shallow subtidal zone, down to 64 m. Commonly found in beach washup. Comparison: Mactra pusilla is similar to this species, but has the umbo behind the midline. Mactra jacksonensis is further differentiated from small specimens of M. pusilla by having a shallow pallial sinus and lacking purple on the umbones and interiorly. Synonymy: Mactra matthewsi Tate 1889 is this species, described from SA. Fig. 1: Port Jackson (Sydney Harbour) NSW (C.016186) Fig. 2: Right valve interior with scars drawn in. Discoloured specimen (C.347027) |
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