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

 

‘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 subsequence 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 detailed analysis of Blakistonia phylogeny and biogeography, to elucidate the interrelationships among species, and explore patterns of biogeography across the mesic and arid zones of temperate Australia. We employ a more comprehensive sampling of taxa and a seven-gene molecular dataset to generate a robust phylogeny, thus building upon previous revisionary works and continent-wide biogeographic studies of other mygalomorph spider genera. We recovered three major species-complexes within Blakistonia, one species-poor complex restricted to the temperate mesic zone, and two much more diverse complexes 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 Plio-Pleistocene. Our results further highlight the biogeographic utility of spiny trapdoor spiders for testing patterns of arid zone diversification, and reveal a complex history of speciation in a previously poorly known group.

Harrison S, Austin A, Cooper S, Marsh J, Rix M, Wilson JD, Harvey M. ‘Lifting the lid’ on relationships among Australian spiny trapdoor spiders of the genus <italic>Blakistonia</italic> Hogg (Araneae: Idiopidae: Arbanitinae). Invertebrate Systematics 2025; IS24095. https://doi.org/10.1071/IS24095