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Isidorella Tate, 1896

Disclaimer

This genus is in need of revision, as the species concepts we have used have not been rigorously tested. Unpublished molecular data indicate that the species units we are here using appear to be justified, however they are not accompanied by clear-cut morphological characters that allow separation based on shell characters alone. As the species units appear to be overall concordant with state boundaries, we have used these boundaries to delimit species. This situation is not ideal. and can only be resolved by additional molecular and morphological studies involving dense sampling.

Diagnostic features

Snails with a medium sized subglobose to globose, sinistrally coiled shell. Low to moderately raised spire with unshouldered to weakly shouldered whorls; with or without narrow umbilicus, whorls rounded with indented sutures. Aperture large, ovate. Outer lip and columella are entire without columella twist or plait.  Smooth or with spiral threads and periostracal setae. Isidorella lacks a stylet and an accessory structure but the penis has two lobes.

Classification

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Planorboidea

Family Planorbidae

Subfamily: Bulininae

Genus Isidorella Tate, 1896

Type species: Physa newcombi A. Adams and Angas, 1864 (= Isidorella newcombi (A. Adams and Angas, 1864))

Original reference: Tate, R. (1896) Mollusca in Baldwin, S. (ed.) Report on the Work of the Horn Scientific Expedition to Central Australia Part II – Zoology. Dulau & Co., London and Melville, Muller & Slade, Melbourne; pp.181-226.

Type locality: Ponds, Mt. Margaret, South Australia.

Biology and ecology

Onaquatic vegetation in ponds, billabongs, swamps, and sluggish streams and rivers. Locally common. Capable of aestivation, biology generally unstudied. Development direct.

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

Mainland Australia.

Notes

Some forms of Glyptophysa  - particularly the species G.(G.) vandiemenensis from Tasmania - are very similar to Isidorella species. However, Isidorella lacks a stylet and an accessory structure, and the penis has two lobes. The taxonomy of Isidorella is very poorly understood.

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.

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.

Walker, J. C. (1988). Classification of Australian buliniform planorbids (Mollusca: Pulmonata). Records of the Australian Museum 40: 61-89.