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Isidorella hainesii (Tryon, 1866)

Diagnostic features

Shell of about 4-5 whorls, with fine spirals and axials and periostracal hairs. Not umbilicate. Reaches about 16 mm in length.

Classification

Isidorella hainesii (Tryon, 1866)

Common name: Haine’s Pouch Snail.

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Planorboidea

Family Planorbidae

Genus Isidorella Tate, 1896

Original name: Physa (Isidora) hainesii Tryon, 1866. Tryon, G.W. (1866). Descriptions of new and exotic fresh-water Mollusca. American Journal of Conchology, 2: 8-11 [9].

Synonyms: Physa inflata A. Adams and Angas, 1864 (preoccupied); Physa subinflata Sowerby, 1874; Physa crebriciliata Tenison Woods, 1878; Physa pilosa Tenison Woods, 1878; Physa brazieri Smith, 1882; Physa brazieri pallida Smith, 1882; Physa brazieri major Smith, 1882; Aplexa rubida Tate, 1882; ?Physa contorta Clessin, 1886; Physa ciliosa Clessin, 1886; Physa hirsuta Hedley 1917; Isidora newcombi hedleyi Clench, 1926; Isidorella brazieri parludia Iredale, 1944; Isidorella brazieri ludia Iredale, 1944; Isidorella montana Iredale, 1943; Isidorella moola Iredale, 1943; Isidorella rubida Cotton, 1947. 

Biology and ecology

On aquatic vegetation in ponds, billabongs, swamps and sluggish streams and rivers. Locally common. Feeds on algae and detritus. Egg mass a round to oval jelly containing several (up to 35 eggs). 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

Victoria and eastern South Australia, New South Wales and southern Queensland.

Notes

This species differs from I. newcombi in having the narrow umbilicus covered by the lower part of the inner lip and the shell is less globose. Both species sometimes have fine spiral granulose striae but, unlike I. newcombi (which sometimes has them developed on the shell), I. hainesii only has these developed on the periostracum.

Some forms of Glyptophysa spp. are very similar to Isidorella species but the penial apparatus has a penial stylet and an accessory flagellum. Isidorella lacks a stylet and an accessory structure but the penis has two lobes.

This genus is in need of revision, as the species concepts we have used have not been rigorously tested and can only be resolved by additional molecular and morphological studies involving dense sampling.

Further reading

Cotton, B. C. (1943). More Australian freshwater shells. Transactions of the Royal Society of South Australia 67: 143-148.

Gabriel, C. J. (1939). The freshwater Mollusca of Victoria. Memoirs of the National Museum of Victoria 11: 100-139.

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

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