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TELLINIDAE |
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Macomona
deltoidalis
(Lamarck, 1818) Description:
Shape elongate-ovate, umbo slightly behind midline, antero-dorsal
margin convex, postero-dorsal margin straight. Posterior end of both
valves flexed to right, ridge from umbo to posterior margin. Exterior
surface chalky, with irregular concentric growth ridges, most prominent
towards ventral margin. Interior with pallial line, anterior and
posterior muscle scars well defined; pallial sinus very deep, extending
three-quarters of shell length. Margin weakly crenulate. Hinge
with 2 cardinal teeth in each valve, 1 bifid, and 2 lateral teeth in
each valve, the anterior close to cardinals, the posterior remote. Ligament
external, long. Shell colour white internally and externally. Periostracum
thin, persisting near margins. Size:
Up to 44 mm in length. Distribution:
Endemic to Australia: Bowen, Qld, southwards and around southern
Australia, to southwestern WA, including Tas. Habitat:
In sand and muddy sand in sheltered coastal lagoons, river mouths
and estuaries. In Sydney Harbour, extends upstream to Parramatta River.
Common, sometimes abundant. Comparison:
In NSW, three species of Tellinidae are similar in being large
and white with commarginal ribs: Macomona
deltoidalis
Chalky surface, commarginal sculpture irregularly spaced, often
only present towards ventral margin. Shell distinctly twisted. Pseudarcopagia
botanica
Fine, regularly spaced commarginal sculpture over the whole
surface. Shell nearly circular. Pristipagia
gemonia
Sculpture same as P. botanica. Postero-dorsal margin long
and convex. Fig.
1:
North Harbour near Manly, NSW (C.97370) |
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