Phylogenetic relationships within the genus Atopobathynella Schminke (Bathynellacea : Parabathynellidae)

The present study attempts to reconstruct the phylogenetic relationships among species of Atopobathynella Schminke, 1973 in order to elucidate their distributional patterns and to seek a mechanism for the worldwide colonisation of the limnic interstitial by the Parabathynellidae. We describe six new Atopobathynella recently discovered in Western Australia: A. gascoyneensis, sp. nov., A. hinzeae, sp. nov., A. schminkei, sp. nov., A. wattsi, sp. nov., A. readi, sp. nov. and A. glenayleensis, sp. nov. The phylogenetic relationships among these species and four previously known species in the genus are assessed using 28 morphological characters. The analysis yielded two most parsimonious trees 71 steps long with consistency index 0.5070, retention index 0.5270, and rescaled consistency index 0.2672. One of these trees supports the grouping of A. readi, sp. nov. + (((A. wattsi, sp. nov. + A. glenaylensis, sp. nov.) + (A. hospitalis Schminke, 1973 (A. gascoyneensis, sp. nov. (A. schminkei, sp. nov. + A. hinzeae, sp. nov.)))) + (A. valdiviana (Noodt, 1964) (A. compagana Schminke, 1973 + A. chelifera Schminke, 1973))). We discuss the monophyly of Atopobathynella and its phylogenetic position within the family Parabathynellidae. The results of the phylogenetic analysis and the biogeographical data suggest that the ancestors of Atopobathynella colonized groundwater via limnic surface water.