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Beddomeia Petterd, 1889

Diagnostic features

Small (between about 2.0 mm and 6.3 mm in maximum length), subpupiform to conic to depressed trochiform. Periostracum thin to well developed, colourless to brown. Teleoconch whorls convex, sculpture of faint growth lines; periphery of last whorl usually evenly rounded, sometimes subangled, rarely sharply angled. Aperture ovate, inner lip thin and narrow to thick and broad, columellar swelling absent or present. Outer lip thin, prosocline (rarely orthocline), never opisthocline. Umbilicus wide to small, or closed and represented by chink.

Operculum oval, flat, thin, transparent pale yellow, simple, with eccentric nucleus. Outer surface with simple growth lines

Beddomeia is mainly distinguished from other tateid genera, including other members of the Beddomeia group, on anatomical characters with the main distinguishing feature being the bursa copulatrix in the female genital system being globular and of medium size, and not extending to the posterior pallial wall. The bursal duct arises from the anterior edge of the bursa. Unlike typical tateids, some species of Beddomeia have a posterior pallial tentacle.

Classification

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Beddomeia Petterd, 1889

Type species: Tasmaniella launcestonensis (Johnston, 1879) [= Amnicola launcestonensis] by subsequent designation (Cotton 1942).

Original reference: Petterd, W. F. (1889). Contributions for a systematic catalogue of the aquatic shells of Tasmania. Papers and Proceedings of the Royal Society of Tasmania 1888: 60-83.

Type locality: Still water, though in communication with the South Esk, in caverns, cataract, Launceston, Tasmania.

Synonyms: Brazieria Petterd, 1889; Petterdiana Brazier, 1896; Tasmaniella Ancey, 1898; Pseudampullaria Ancey, 1898; Petterdiella Pilsbry, 1900; Beddomena Iredale, 1943; Valvatasma Iredale, 1943

State of taxonomy

We follow Ponder et al. (1993) in this resource. There are several more Beddomeia taxa in Tasmania than are currently recognised by Ponder et al. (1993).

Biology and ecology

In rivers, lakes, seeps and streams under stable rocks in strong flow or in still water under leaves, under sedges, on roots, on macrophytes, moss, and on submerged logs in side channels and pools. Egg capsules ovoid, dome-shaped, with broad attachment base, covered with minute, mainly white sand grains and other fragments; 0.67-1.33 mm in maximum length; containing a single egg. Development is direct.

Distribution

Northern Tasmania, with two taxa doubtfully included in the genus in south-western Tasmania.

Notes

All species of Beddomeia are geographically isolated and have restricted ranges.

At least one species (Beddomeia tumida) is possibly extinct due to flooding of its habitat for a hydroelectric project. Several other species have very small ranges and some of those are threatened or vulnerable.

Recent work by Wilke et al. (2013) revealed that this genus, like Phrantela and Victodrobia,  are not closely related to other Tateidae.

Further reading

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

Cotton, B. C. (1942). Australian Gastropoda of the families Hydrobiidae, Assimineidae and Acmeidae. Transactions of the Royal Society of South Australia 66: 124-129.

Johnston, R. M. (1879). Further notes on the fresh-water shells of Tasmania (with a description of a new species). Papers and Proceedings of the Royal Society of Tasmania 1879: 19-29.

Ponder, W. F., Clark, G. A., Miller, A. C. & Toluzzi, A. (1993). On a major radiation of freshwater snails in Tasmania and eastern Victoria: a preliminary overview of the Beddomeia group (Mollusca: Gastropoda: Hydrobiidae). Invertebrate Taxonomy 7: 501-750.  

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.

Smith, B. J. & Kershaw, R. C. (1981). Tasmanian Land and Freshwater Molluscs. Hobart, University of Tasmania.

Wilke, T., Haase, M., Hershler, R., Liu, H.-P., Misof, B. & Ponder, W. (2013). Pushing short DNA fragments to the limit: Phylogenetic relationships of 'hydrobioid' gastropods (Caenogastropoda: Rissooidea). Molecular Phylogenetics and Evolution 66: 715-736.