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Beddomeia trochiformis Ponder & Clark, 1993

Diagnostic features

Species in the B. tasmanica group have small shells (length 1.2-2.8 mm) with a depressed spire and open umbilicus. The penis is simple. 

This species differs from other members of the group in possessing a radula with a moderately indented dorsal edge of the central teeth, the latter also with teeth steeper outer edges (40°, compared with 45") and ratio of lateral teeth cutting edge to shaft 0.5 (~0.43 in other taxa); pallial cavity with fewer ctenidial filaments (15-19); female genital system with initial U-bend of coiled oviduct orientated obliquely backwards (not dorso-ventral).

Classification

Beddomeia trochiformis Ponder & Clark, 1993

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha

Superfamily Truncatelloidea

Family Tateidae

Genus Beddomeia Petterd, 1889

Original name: Beddomeia trochiformis 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: Bowry Creek, tributary of Savage River, side road off Corinna Road, Tasmania.

Biology and ecology

Under stones in streams. The white egg capsules are laid on the undersides of stones and are 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

This species and B. franklandensis occur in westward draining rivers in the north western part of Tasmania. It is very common in the type locality.

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.