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.