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SEMELIDAE |
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Theora
lubrica
A.A.Gould, 1861 Description:
Shell translucent. Shape elongate-ovate, posterior and
anterior ends rounded, posterior narrower. Umbo in front of midline. Exterior
polished, with weak irregular commarginal growth ridges. Interior
with a strong narrow ridge from umbo to anterior end of shell in both
valves; otherwise smooth, muscle scars and pallial line weakly defined;
pallial sinus extends past midline.
Hinge with single bifid cardinal tooth in left valve, 2
cardinals in right valve; lateral teeth long in both valves. Ligament
in two parts; dorsal part exterior, ventral part on prominent
spoon-shaped projection. Shell colour translucent white. Size:
In NSW, up to 13 mm in length. Distribution:
Endemic to the northwestern Pacific Ocean, from southern Russia
and northern Japan to the Hong Kong region but introduced to Europe,
Mediterranean Sea, west coast of North America, Australia, New Zealand
and Brazil. In Australia, it is known from NSW (Sydney Harbour, Port
Hacking), Vic, Tas, WA (Geraldton Harbour). Habitat:
Lives in burrows in the lower intertidal and subtidal zones in
muddy situations, in harbours and estuaries. Comparison:
See Theora lata. Remarks:
This is an invasive species, probably spread in ship’s ballast
water. It continues to be spread worldwide, most recently being reported
from Brazil and the United Kingdom. Fig.
1:
Port Hacking, Sydney, NSW (C.378035) |
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