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Gyraulus (Pygmanisus) scottianus (Johnston, 1879)

Diagnostic features

Can be distinguished from all other Gyraulus species by its slowly increasing rounded whorls, flat open spiral shape, and small size. It is also anatomically distinct (Brown 1998).


Gyraulus (Pygmanisus) scottianus (Johnston, 1879)

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Planorboidea

Family Planorbidae

Genus Gyraulus Charpentier, 1837

Subgenus Pygmanisus Iredale,1943 (Type species: Planorbis scottiana Johnston, 1879).

Original name: Planorbis scottiana Johnston, R. M., 1879. Johnston, R. M. (1879). Further notes on the fresh-water shells of Tasmania. Papers and Proceedings of the Royal Society of Tasmania 1878: 19-29.

Synonyms: Pygmanisus leonatus Iredale, 1943; Pygmanisus pelorius Iredale, 1943; Pygmanisus parvus Cotton, 1943.

Biology and ecology

This species lives on aquatic vegetation in ponds, billabongs, swamps and sluggish streams and rivers. Feeds on detritus. Egg mass presumably a jelly strip containing small eggs. Development direct. Brown (1998, 2001) describes the anatomy of this species.


South-eastern Australia, Tasmania and Lord Howe Island.

Further reading

Brown, D. S. (1981). Observations on the Planorbidae from Australia and New Guinea. Journal of the Malacological Society of Australia 5: 67-80.

Brown, D. S. (1998). Freshwater snails of the genus Gyraulus (Gastropoda: Planorbidae) in Australia: the taxa of Tasmania. Molluscan Research 19: 105-154.

Brown, D. S. (2001). Freshwater snails of the genus Gyraulus (Planorbidae) in Australia: taxa of the mainland. Molluscan Research 21: 17-107.

Hubendick, B. (1955). Phylogeny of the Planorbidae. Transactions of the Zoological Society of London 28: 453-542.

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

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. and Kershaw, R. C. (1979). Field guide to the non-marine molluscs of south eastern Australia. Australian National University Press, Canberra, Australia.

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