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Ostrea virescens Angas, 1867      Viridescent Oyster

Description: Paraphrased from original description: Shell solid Shape orbicular (i.e., circular). Upper valve smaller, flattened, radially plicate (i.e., folded), with scaley lamellae. Lower valve deep. Hinge area large, triangular, flattened. Interior greenish-olive, palish at margins. Exterior with scaley lamellae, margins crenulate, frilled. Shell colour of upper valve whitish, irregularly striped with purplish brown.

Size: Original description 1¾ inches long, 1½ inches wide (44 mm long, 38 mm long).

Distribution: Holotype from Watsons Bay, Sydney Harbour.

Habitat: Original description “attached to rocks and madrepores (stony corals) at low spring tides”, Watsons Bay, Sydney Harbour”.

Comparison: This species is distinguished by the greenish interior.

Synonymy: Because of the uncertainty in identifying specimens of this species there have been many synonyms proposed. Huber (2015) has used Ostrea stentina Payraudeau, 1826 named from Corsica in the Mediterranean, which assumes the species has a worldwide distribution. However, until this hypothesis is tested by genetic analysis it is preferred to continue with the established local name.

Remarks: Since it was described in 1867 this species has been problematic as no specimens have been reported or are in the Australian Museum collection that even closely resemble the original illustration (Fig. 1). There are, however, about 10 lots of oysters from the Sydney region that show a green interior, and these have been assumed to be this species. One of these specimens is shown in Fig. 2. On the other hand, specimens closely matching the original description are well known from New Zealand and common in harbours there.

Fig. 1: Figure from original description by Angas (1867) from Proceedings of the Zoological Society of London (1867) pl. 44, fig. 13.

Fig. 2:  Brotherson Dock, Botany Bay, NSW. On wharf pylons. (C.398557)


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