On a major radiation of freshwater snails in Tasmania and eastern Victoria: a preliminary overview of the Beddomeia group (Mollusca : Gastropoda : Hydrobiidae)

Abstract

A total of 67 taxa, forming part of a major radiation of freshwater hydrobiid snails in Tasmania and eastern Victoria, are described. Four genera are recognised within the radiation: Beddomeia (47 taxa), Phrantela (13 taxa), Nanocochlea, gen. nov. (three taxa) in Tasmania and Victodrobia, gen. nov. (four taxa) in eastern Victoria. Fifty-nine of the species-group taxa are newly described, three of these being given subspecific status. Species-group taxa are separated using morphological data based on 78 characters from the shell, radula, non-genital and genital anatomy.

Individual taxa appear to occupy a rather small range of habitats, although within the radiation species are found in many different environments ranging from large rivers to tiny seeps and springs or caves. Nearly all taxa occupy very small geographic ranges, 38 being known only from single localities. Maps indicating the distributions of described taxa and additional populations with similar shell morphologies (but otherwise unworked) are presented.

A preliminary phylogenetic hypothesis based on a cladistic analysis, and an overview of the biogeography of the group are presented and conservation considerations are discussed.