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Helicorbis australiensis (Smith, 1882)

Diagnostic features

This species differs from members of the genus Gyraulus by its strongly overlapping whorls and peripheral keel that is not centrally placed. The shell is smooth, shiny, and dark red-brown to pale amber when alive. It is small and flat, with a small to medium sunken spire and narrow to medium umbilicus. Some individuals have small internal lamellae.

Classification

Helicorbis australiensis (Smith, 1882)

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Planorboidea

Family Planorbidae

Genus Helicorbis Benson, 1855 (Type species: Planorbis umbilicalis Benson, 1850, Chusan Island, China = Zhoushan Island) (= Segnitila Cotton and Godfrey, 1938)

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

Type locality: Penrith, New South Wales.

Synonyms: Planorbis meniscoides Tate, 1882; Segmentina victoriae Smith, 1882; Segnitila alphena Iredale, 1943; Segnitila idonea Iredale, 1944; Segnitila redita Iredale, 1944; Segnitila brisbanensis Iredale, 1944.

State of taxonomy

We follow Brown (1981) while noting that the taxonomy of this group requires revision (see Notes).

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 (1981) 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

Southern, eastern and northern Australia and a few records from Tasmania.

Notes

This species differs from species of Gyraulus in having the whorls strongly overlapping and the peripheral keel is not centrally placed. The shell is smooth, shining and dark red-brown when alive.

This genus occurs in China, India, Philippines, islands of the western Pacific, as well as in eastern and northern Australia.

Related genera are Hippeutis Agassiz, 1837 and Intha Annandale, 1922 and the relationships of these genera and Helicorbis require re-examination. Some species in these genera are hosts of signifant animal and human parasites. Hippeutis (or Intha) umbilicalis (Benson, 1836), an Asian species that is also known from New Guinea,  has been intercepted by Australian Biosecurity.  

Further reading

Baker, F. C. (1945). The molluscan family Planorbidae. Urbana USA, University of Illinois Press.

Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.

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.

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. 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.

Smith, E. A. (1887). Notes on Australian species of Bithinia, Segmentina, and Fusus and description of a new Melania. Journal of Conchology 5: 235-238.