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Fifteen species of the Gondwanan genus Atopobathynella have been described so far from four countries. The position of the genus within the family Parabathynellidae and its species relationships are controversial due to the different characters and species considered by different authors, however most of the phylogenetic reconstructions are based solely on morphological characters. In the past few decades, the arid zones of Western Australia, including the Pilbara region, have been recognized as a hotspot for subterranean fauna. Material is constantly collected to produce Environmental Impact Assessments to protect and manage the subterranean environment. In 2009 the Cleaverville Iron Formation, in the Pilbara region, northern Western Australia, was proposed to be mined, therefore subterranean fauna sampling was conducted as per legislation. Preliminary molecular studies of stygofauna identified two distinct Parabathynellidae lineages from two ridges, however no morphological descriptions were carried out at that time. In this study, we describe two new species from Yarrie and Callawa ridges, respectively: Atopobathynella yarriensis sp. nov. and A. degreyensis sp. nov.. The new species show differences in male antennal organ, ventral tooth of mandible, number of teeth on distal endite of maxillula, absence or presence of epipod of thoracopod I, number of setae on article 4 of thoracopod II, length of distal external seta of exopod of all thoracopods, outer lobe of male thoracopod VIII, number of spines on uropodal sympod and furcal rami, length of the external dorsal plumose seta of the furcal rami. Additionally, we integrated the morphological data with sequences of three genetic loci, Cytochrome Oxidase c Subunit I (COI), 12S rRNA (12S), and nuclear 18S rRNA (18S), calculating p-distances and constructing a multigene molecular phylogeny to support morphology, and explore the monophyletic status of the genus and the relationship amongst its species. The two new spe

The Hexabathynella genus is the only genus of the family Parabathynellidae that has supposedly a worldwide distribution. Currently, there are 23 species described from five continents. In Australia, only two Hexabathynella species have been named from the eastern coast, however, a few taxa have been collected from Western Australia during stygofauna sampling as part of research studies and legislated compliance-based Environmental Impact Assessments. One of these areas includes Rottnest Island (Wadjemup), located offshore of Perth in Western Australia. Unpublished data on stygofaunal communities inhabiting the groundwater of the island refer to discrete abundances of copepods and syncarids, but no species description has been carried out. In this study, we describe two new species: Hexabathynella quokkai and H. bisetosa, expanding the characterization of the subterranean aquatic community at Rottnest Island, and using a COI, 18S and 12S sequence-based phylogeny to test the monophyletic status of the genus. Our findings shed new light on the distribution of Hexabathynella and its reported cosmopolitan distribution.