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Gyraulus (Gyraulus) essingtonensis (Smith, 1882)

Diagnostic features

The shell shape varies from depressed with a keel and fringe to high-whorled with only an obtuse angle on the periphery. The spiral sculpture also varies within and between samples, from very weak spiral  ridges and is sometimes reticulate. Some strongly sculptured forms are similar to G. hesperus but that species differs anatomically (prostate with more lobes) and has a more elevated shell.

Classification

Gyraulus (Gyraulus) essingtonensis (Smith, 1882)

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Planorboidea

Family Planorbidae

Genus Gyraulus Charpentier, 1837

Original name: Planorbis essingtonensis Smith, E.A. (1882). Smith, E.A. (1882). On the freshwater shells of Australia. Journal of the  Linnean Society of London, Zoology 16: 255-316.

Type locality: Port Essington, Northern Territory.

Synonyms: Glyptanisus coranus Iredale, 1943

Biology and ecology

This species lives in water weeds and other vegetation in waterholes, ponds, billabongs, swamps and sluggish streams and rivers from the Red Centre to tropical northern Australia. Feeds on detritus. Egg mass presumably a jelly strip containing small eggs. Development direct.

Brown (2001) described the anatomy of this species.

Additional information on the biology and ecology of members of this family can be found in Fauna of Australia, vol. 5B, p. 1072-1074.

Distribution

This species occurs in northern and central Australia, from the Gulf of Carpentaria to the Pilbara, possibly extending as far south as Perth - it also extends very far inland, to the Northern Territory-South Australian border.

Notes

This species exhibits extreme variability in size, sculpture, peripheral angulation and whorl count; it could possibly be conspecific with G. gilberti according to Brown (2001).

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.

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.