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Beddomeia fallax Ponder & Clark, 1993

Diagnostic features

Species of the B. hullii group are found in the northern half of Tasmania. Their shells are small (1.7-3.7 mm in length; most less than 3.5 mm), simple, ovate-conic to broadly conic, with a thin inner lip and no columellar bulge. The periphery of the last whorl of the shell is rounded, subangled or angled and the penis simple.

This species differs from other members of the group  with regards to its radula with sharply pointed median cusps on central and lateral teeth (blunter in other taxa); male genital system with prostate gland extending only 1/3 of length into pallial roof (1/2 or more in other taxa); female genital system with coiled oviduct extending beyond posterior edge of bursa copulatrix (not beyond posterior edge in other taxa) and albumen gland extending into pallial wall about 1/3 of length (more in other taxa).

Classification

Beddomeia fallax Ponder & Clark, 1993

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Beddomeia Petterd, 1889

Original name: Beddomeia fallax Ponder & Clark, 1993 in Ponder, W.F., Clark, G.A., Miller, A.C. and 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. 

Type locality: Heathcote Creek, on Castra Road, Upper Castra, Tasmania.

Biology and ecology

This species lives under stones in a small stream. Egg capsules presumably like those of other species of Beddomeia - dome-shaped, with broad attachment base, covered with minute, mainly white sand grains and other fragments and containing a single egg. Development direct.

Distribution

Only known from Heathcote Creek, Upper Castra and a few nearby locations in mid-northern Tasmania.

Notes

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

This species is on the Tasmanian Threatened species list of Invertebrate Animals as Rare (small population at risk).

Further reading

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.