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TRIGONIIDAE |
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Neotrigonia gemma Iredale, 1924 Description: Shell solid and heavy. Shape ovate, anterior and ventral margins uniformly rounded, posterior margin truncate or rounded, postero-dorsal margin convex. Exterior bearing regular, conical sharply pointed nodules (Fig. 2); grooves between radials initially unsculptured, developing weak concentric riblets ventrally. Interior nacreous, silver; muscle scars close to hinge; grooved ventrally, with interlocking scalloped margin. Hinge very strong, with 2, narrow, elongate, deep sockets in left valve and 2 matching blade-like teeth in right valve. Shell colour white under a smooth, flaking periostracum. Size: Up to 14 mm in height. Distribution: Endemic to Australia: off North Stradbroke Island, Qld, southwards to off Cape Everard, Vic. Habitat: Subtidal, 50-150 m depth. Comparison: This species differs from N. margaritacea by its smaller size, more ovate shape, regular pointed nodules, and only ever silver colour internally. Fig. 1: Off Port Hacking, NSW, in 75-85 m (C.070417) Fig. 2: Same specimen as Fig. 1. Oblique view showing sculpture. |
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