Planigales (Marsupialia : Dasyuridae) of eastern Australia's interior: a comparison of morphology, distributions and habitat preferences, with particular emphasis on South Australia

Abstract

Correct species identification is an essential step in characterising an organism’s geographic range and ecological requirements. In this study the morphology, distribution and habitat preferences of eastern Australia’s three species of inland planigales, Planigale ingrami, P. tenuirostris and P. gilesi, were compared, particularly to establish consistent differences between the morphologically similar Planigale ingrami and P. tenuirostris, which earlier molecular evidence had suggested were easily misidentified. Specimens that had previously been characterised genetically were examined to find diagnostic morphological characters for each species. External measurements indicated that P. tenuirostris was larger than P. ingrami, but size ranges overlap considerably. Several external characters, including basal width of the supratragus and foot morphology, differentiate each species; however tail length was not a reliable distinguishing character. Bivariate plots of several skull characters also enabled species identification. Competition within each species may be reduced by sexual dimorphism in dental morphology, while differences in skull shape may indicate past character displacement between Planigale species. In South Australia P. ingrami and P. tenuirostris are broadly sympatric with P. gilesi but not with each other. There appears to be ecological habitat separation between all three species, with P. ingrami being the most restricted in distribution and habitat requirements, P. gilesi occurring in similar habitats but in a wider range of vegetation communities, and P. tenuirostris being the least tied to flood-prone habitats.