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Posticobia brazieri (Smith, 1882)

Diagnostic features

This species differs from other New South Wales tateids in its short, broad shell. Like species of Fluvidona and Austropyrgus, adults have a slightly thickened aperture, and an operculum bearing several pegs. It may be very common. Some populations mostly consist of smooth-shelled individuals, whereas others have a distinct keel on the periphery of the last whorl.

Classification

Posticobia brazieri (Smith, 1882)

Common name:  Brazier's pebble snail

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha 

Superfamily Truncatelloidea

Family Tateidae

Genus Posticobia Iredale, 1943

Original name: Hydrobia brazieri Smith, 1882. Smith, E.A.1882. On the freshwater shells of Australia. Journal of the Linnean Society of London, Zoology 16 (92): 225-316.

Type locality: Clarence River, South Grafton, New South Wales.

Biology and ecology

On wood, stones, sediment and water weed; often abundant. Assumed to feed by scraping bacteria and microalgae. Solitary hemispherical capsules with single egg. Direct development. Populations are in slightly brackish to freshwater.

Distribution

Found mainly in the coastal rivers of the eastern half of the Northern Territory and in coastal rivers and lakes of Queensland and New South Wales. A few widely scattered populations are also known from South Australia and western Victoria.

Further reading

Clark, S. A. (2009). The genus Posticobia (Mollusca: Caenogastropoda: Rissooidea: Hydrobiidae SL) from Australia and Norfolk Island. Malacologia 51: 319-341.

Clark, S. A., Miller, A. C. & Ponder, W. F. (2003). Revision of the snail genus Austropyrgus (Gastropoda: Hydrobiidae): a morphostatic radiation of freshwater gastropods in southeastern Australia. Records of the Australian Museum 28: 1–109.

Ponder, W. F. (1981). Posticobia norfolkensis (Sykes), an apparently extinct fresh-water snail from Norfolk Island, Australia (Gastropoda, Hydrobiidae). Proceedings of the Linnean Society of New South Wales 105: 17-21.

Ponder, W. F., Clark, S. A. & Dallwitz, M. J. (2000). Freshwater and estuarine molluscs: an interactive, illustrated key for New South Wales. Melbourne, CSIRO Publishing.

Smith, B. J. (1992). Non-marine Mollusca. Pp. i-xii, 1-408 in W. W. K. Houston. Zoological Catalogue of Australia, 8. Canberra, Australian Government Publishing Service.

Smith, B. J. & Kershaw, R. C. (1979). Field guide to the non-marine Molluscs of South-eastern Australia. Canberra, A.N.U. Press.

Shea, M. 1995. Freshwater molluscs of Sydney. Australian Shell News 88: 4-6.