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); mantle cavity with fewer ctenidial filaments (15-19); female genital system with initial U-bend of coiled oviduct orientated obliquely backwards (not dorso-ventral).
Beddomeia trochiformis Ponder & Clark, 1993
Class Gastropoda
Infraclass Caenogastropoda
Order Littorinida
Suborder Rissoidina
Superfamily Truncatelloidea
Family Beddomeiidae
Original name: Beddomeia trochiformis Ponder & Clark, 1993. In 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.
Type locality: Bowry Creek, tributary of Savage River, side road off Corinna Road, Tasmania.
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.
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.
All species of Beddomeia are geographically isolated and have restricted ranges.
This species is on the Tasmanian Threatened Species Protection Act 1995 as Rare (small population at risk).
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.
