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Barbatia pistachia (Lamarck, 1819)

Description: Equivalve, inequilateral. Shape elongate, umbones in front of midline, elevated, widely separated (Fig. 2). Hinge line straight. Anterior and posterior ends broadly rounded, ventral margin sinuate, byssal notch gaping. Hinge with large teeth at ends, becoming smaller towards middle, sometimes completely absent from middle section. Ligament external, spread over ridged area between umbones. Interior with marginal edge smooth, glossy; anterior and posterior muscle scars almost circular; sometimes with widely spaced radial grooves. Exterior sculpture of beaded radial ridges and irregular, coarse, concentric growth ridges. Periostracum dark brown bristles, longer on posterior end and near ventral margin. Shell colour white, fawn or blotched with purple, in life obscured by periostracum.

Size: Up to 80 mm in length. (The measurement of 54 mm given by Lamprell & Healy (1998) is probably the type dimension).

Distribution: Endemic to Australia: Whitsunday Islands, Qld, southwards and around southern Australia to Kimberley region, northern Western Australia, including Tasmania.

Habitat: Lives on rocky shores attached by the byssus to solid substrates, in the low intertidal zone and below. Common.

Comparison: See B. parvivillosa.

Synonymy: Specimens obtained from 75-80 fathoms (137-146 m) off Narrabeen, NSW, were named Barbatia pistachia separata Iredale, 1925 apparently because of their deeper water habitat.

Fig. 1: Balmoral, Middle Harbour, Sydney, NSW (C.093869)

Fig. 2: Same specimen as Fig. 1

 

 


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