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THYASIRIDAE |
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Parathyasira resupina Iredale, 1930 Description: Shape shell with single strong posterior fold and a deep, narrow postero-dorsal fissure; height slightly greater than width, umbo central, lunule large, shallow, poorly defined. Exterior with irregular growth ridges, smooth dorsally; very fine, dense radial threads, more obvious towards ventral margin. Furry periostracum present towards ventral margin. Interior smooth, muscle scars not apparent, margin smooth. Hinge without teeth. Ligament mainly internal, long, narrow. Shell colour white. Size: Up to 9 mm high. Distribution: Known from off Coffs Harbour, NSW, southwards to off Port Kembla, NSW. Habitat: Subtidal, 28-130 m depth. Comparison: This is similar to Prothyasira peroniana. It differs by the posterior fold being weaker, by lacking commarginal riblets (although growth ridges are present), and having fine radial sculpture. The ligament is in a deep, narrow fissure (Fig. 2), the equivalent structure being much broader in P. peroniana. Fig. 1: 2.2 km east of Cape Banks, NSW, in 49 m (C.unreg) Fig. 2: 9 km east of Cape banks, NSW, in 98 m (C.unreg) |
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