Shell variation in Australian Notopala (Gastropoda: Prosobranchia: Viviparidae)

Abstract

The viviparid snail Notopala is distributed throughout the rivers and other waterbodies of the northern tropical regions of Australia, extending south into the Lake Eyre and Murray-Darling Basins. Despitearecentexarnination of the WesternAustralian viviparids the taxonomy of a number of species, especially those from the Lake Eyre and Murray-Darling Basins, is unclear. Principal Components Analysis was used on seven shell measurements to determine which morphometric characters best delineate the species. Umbilicus width and aperture lip length explained most of the variation. The results suggest that there are four species of Notopala in Australia: N. waterhousii andN. essingtonensis in the north and northwest, N. sublineaca in the Lake Eyre and Murray-Darling Basins and N. hanleyi in the Murray-Darling Basin. With lheapparentextinction of both species ofNotopala in the natural environment of the Murray-Darling Basin, the population of N. hanleyi surviving in a Murray irrigation pipeline and the population of N. sublineata in the Lake Eyre Basin have significant conservation value.