The freshwater crayfish genus Parastacoides presents an ideal opportunity to study a species-rich genus in a relatively undisturbed area. Parastacoides is endemic to the western regions of Tasmania, thus its distribution is, to a great extent, within the Western Tasmania World Heritage Area. Although the current taxonomic status recognizes one species, consisting of three sub-species, recent unpublished work suggests that the genus is far more diverse, and 14 species will be described. Records from the extensive collection in the School of Zoology, University of Tasmania were examined an d details of vegetation, habitat, substrate and geology were analysed. All species exhibit a broad habitat range, and some are opportunistic exploiter s of novel habitats, such as roadside gravel and under walking track cording. Although patterns of habitat exploitation appear to differ between species , no systematic broad scale variation was apparent. Habitat usage and speciation therefore does not appear to be due primarily to adaptive radiation.