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DONACIDAE |
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Donax brazieri E.A. Smith, 1892 Description:
Shape nearly triangular; umbo slightly posterior to
midline, shell strongly angled posteriorly; anterior margin straight or
slightly convex, posterior margin straight. Exterior polished,
anterior end smooth with weak radial lines, posterior end with lines
becoming stronger, dense, and nodulose on posterior slope. Interior
with muscle scars and pallial line indistinct, pallial sinus long,
reaching three-quarters of shell length. Ventral margin strongly
crenulate. Hinge
strong, left valve with massive triangular cardinal tooth; right valve
with gap between two cardinals to accommodate left valve cardinal, both
valves with a lateral each side. Ligament
external. Shell white or fawn, sometimes tinged with purple, with
darker commarginal bands; umbo darker purple. Periostracum
not seen. Size: Up to 20 mm in length, 16 mm in NSW. Distribution: Known from southern Australia,
from Morris Is, northern Cape York, Qld, southwards and around southern
Australia, to North West Cape, WA. Habitat: Assumed to be shallow subtidal in
sand. Common. Synonymy: This species displays considerable
variation in proportions of length to height over its long range. It was
first described from Richmond River, northern NSW, where the shells are
relatively elongate. The
name Deltachion virilis Iredale, 1930 was applied to shells from
Sydney, which are more triangular in shape than northern NSW shells. Deltachion
electilis Iredale, 1930 was applied to slightly larger shells, up to
20 mm in length, from South Australia (NEW SYNONYM). Fig. 1: Spec.
1 & 2 Sydney, S. Cronulla (C.369007). Spec.
3 Black Rock, north of Richmond River (C.369040) |
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