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MYTILIDAE |
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Arcuatula glaberrima (Dunker, 1857) Description: Shape equivalve, inequilateral, very elongate, light in weight, with umbo a little behind anterior end. Dorsal margin nearly straight; posterio-dorsal end extended; ventral margin gently curved. Hinge without teeth. Ligament long, occupying most of dorsal margin. Interior smooth, slightly nacreous, muscle scars obscure, external pattern showing through. Exterior with weak concentric growth lines. Colour pale fawn with reddish brown concentric bands and zigzags. Periostracum thin, glossy, fawn. Size: Up to 45 mm in length. Distribution: Albany, WA, around northern Australia to southern NSW. Habitat: Occurs subtidally, down to 73 m depth, occasionally as beach wash-up. Comparison: A species similar to this is Arcuatula senhousia (Benson, 1842), commonly known as the Asian Bag Mussel (Fig. 2). This is a native of the north-western Pacific coasts, with a range from Siberia and the Kuril Islands southwards through Korea, Japan and China. It is similar in shape to A. glaberrima but less elongate and smaller, only reaching up to about 30 mm in length. Arcuatula senhousia has been introduced accidentally by shipping to Australia, New Zealand, the Pacific coast of USA and the Mediterranean Sea. In Australia it is known from the Swan River estuary near Perth and Cockburn Sound, as well as South Australia, Victoria and Tasmania. It has not been recorded from NSW, although it has long been considered that it would find a suitable habitat in estuaries here. Fig. 1: Off Eden, NSW in 73 m (C.31247) Fig. 2: Arcuatula senhousia. Swan River Estuary, WA. (C.148783)
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