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Glyptophysa (Glyptophysa) vandiemenensis (Sowerby, 1873)

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 Unpublished molecular data indicate that the species units we are here using appear to be justified, however they are not accompanied by clear-cut morphological characters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 aid in delimiting species. This situation is not ideal, and can only be resolved by additional molecular and morphological studies involving dense sampling.

Diagnostic features

The taxonomy of Glyptophysa is very poorly understood. This is one of several species of relatively smooth shelled Glyptophysa that are variable in shape and in periostracal development (periostracal hairs and spirals can be present), even within a single population. A large number of species-group names are available and it is quite possible that more species occur in Australia. At present we are recognising only three, in addition to G. aliciae.

This species, as currently recognised, is restricted to Tasmania.

This species has a broader shell and greater periostracal development compared with the other Tasmanian species G. (G.) novaehollandica (note that the name G.(G) nitida (Sowerby, 1874)  is the earlest available name for the Tasmanian novaehollandica-like form should it eventually prove to be distinct). G.(G) vandiemenensis superficially resembles some species of Isidorella, a genus that does not occur in Tasmania.

Classification

Glyptophysa (Glyptophysa) vandiemenensis (Sowerby, 1873)

Common name: Isidorella-like Pouched Snail

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Planorboidea

Family Planorbidae

Genus Glyptophysa Crosse, 1872

Subgenus Glyptophysa

Original name: Physa vandiemenensis Sowerby, 1873. Sowerby, G. B. (1873). Monograph of the genus Physa in Reeve, L.A. Conchologia Iconica London, L. Reeve and Co.Vol. 19 Physa pls. 2-10.

Type locality: Tasmania.

State of taxonomy

The taxonomy of Glyptophysa is very poorly understood. A large number of species-group names are available and it is quite possible that more species occur in Australia. This form from Tasmania (G.(G) vandiemenensis) has an inflated shell with a relatively low spire and superficially resemble Isidorella spp.

This species is one of three that we are somewhat tentatively recognising (see statement under Notes) that were previously often referred to as Glyptophysa gibbosa (now treated as a synonym of G. novaehollandica). These taxa are in need of revision, as the species concepts we have used have not been rigorously tested.  

Biology and ecology

On water weeds, wood etc., in ponds, billabongs, swamps and sluggish streams and rivers. Feeds on algae and detritus. Egg mass typically a bean (kidney)-shaped jelly strip containing many small 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

Tasmania.

Notes

This species is similar to the common introduced Haitia acuta (Physidae) in that both have similar-shaped, sinistral shells. Glyptophysa can be distinguished by the shell not being completely smooth (as it is in Haitia), Glyptophysa often - but not always - having some periostracal ornament. Haitia has a mottled mantle which can usually be seen through the semi- transparent shell whereas Glyptophysa has a uniformly dark-coloured mantle. The animal of Haitia has digitations (finger-like processes) along the mantle edge against the columella whereas this is smooth in GlyptophysaHaitia lacks a false gill (pseudobranch) which is present in Glyptophysa and all planorbids. The animal of Glyptophysa, if damaged when alive, has red-coloured blood whereas Haitia does not produce coloured blood.

Glyptophysa differs from the otherwise similar genus Isidorella in the penial apparatus having a penial stylet and an accessory flagellum. Isidorella lacks a stylet and an accessory structure but the penis has two lobes.

Further reading

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

Kershaw, R. C. (1975). Tasmanian aquatic non-marine Mollusca. Part 1. Lymnaea. Tasmanian Naturalist 40: 1-4.

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. (1981). Tasmanian Land and Freshwater Molluscs. Hobart, University of Tasmania.

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