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Austropyrgus gunnii (Frauenfeld, 1863)

Diagnostic features

This species belongs to the Austropyrgus sparsus group, whose members are characterised by the following shell features: small to medium sized shells, conical, with convex to slightly convex whorls. Furthermore, in females, the coiled oviduct is of an inverted U-shape or with two or more bends, loops or twists.

Austropyrgus gunnii differs from the other species of this group in the following combination of characters: shell small to medium in size, spire outline straight, with convex whorls; central teeth with 6–7 lateral cusps; lateral teeth with 6–8 cusps; inner marginal teeth with 32–35 cusps; pallial vas deferens straight or slightly undulating at prostate gland and with several coils or S-shape bends between prostate gland and penis; anterior end of capsule gland blunt.

Classification

Austropyrgus gunnii (Frauenfeld, 1863)

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Austropyrgus Cotton, 1942

Original name: Hydrobia gunnii Frauenfeld, 1863. Frauenfeld, G. R. (1863). Vorläufige aufzählung der arten der gattungen Hydrobia Htm. und Amnicola Gld. Hldm. in der kaiserlichen und Cuming’s Sammlung. Verhandlungen de Zoologisch-Botanischen Gesellschaft, Wien 13: 1017–1032. 

Type locality: Tasmania - here restricted to South Esk River, Cataract Gorge, Launceston, Tasmania.

Biology and ecology

In streams on water weeds, hard substrate (rocks etc.) and crawling on litter and sediment. Can be locally abundant. Assumed to feed by scraping bacteria and microalgae. Lay solitary capsules containing a single egg. Direct development.

Additional information on the biology and ecology of members of this family can be found in Fauna of Australia, vol. 5B, p. 752-755.

Distribution

This species is found throughout the drainage of the South Esk River, northern Tasmania.

Notes

Although most species of Austropyrgus are geographically isolated and have restricted ranges, a few - such as A. gunnii - have wider ranges.

Further reading

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.

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

Smith, B. J. & Kershaw, R. C. (1981). Tasmanian Land and Freshwater Molluscs. Hobart, University of Tasmania.