‘Lifting the lid’ on relationships among Australian spiny trapdoor spiders of the genus Blakistonia Hogg (Araneae: Idiopidae: Arbanitinae)

Since the Eocene the Australian continent has experienced a long history of climatic and biotic change, resulting in evolutionary diversification among numerous old endemic lineages. Spiny trapdoor spiders of the family Idiopidae are one such group, with previous evidence for three independent incursions into the Australian arid zone from temperate mesic ancestors, leading to subsequent range expansion and diversification in those lineages. One of these arid zone incursions occurred in the genus Blakistonia Hogg, 1902, which ranges widely across much of southern, central and temperate mainland Australia. In this study, we undertake a phylogenetic analysis of Blakistonia to elucidate the interrelationships among species and the timing of diversification across Australia. We employ a broader sampling of taxa relative to previous studies, and a seven-gene molecular dataset to generate the largest multi-locus phylogeny of the genus to date, thus building upon previous revisionary works and continent-wide biogeographic studies of other mygalomorph spider genera. We recover three major clades within Blakistonia, one monotypic clade restricted to the temperate mesic zone, and two diverse clades widely distributed through transitional and arid regions of southern Australia. Diversification of arid-adapted clades commenced in the late Miocene, commensurate with the climatic expansion of the arid zone during the Miocene and Plio-Pleistocene.