Description and evolutionary biogeography of the first Miocene jumping spider (Aranaea: Salticidae) from a southern continent

Abstract

Abstract Examination of a fossil from a Miocene Konservat-Lagerstätte (c. 11–16 Mya) from Australia shows it to be an astioid jumping spider that is here described as Simaetha sp. indet. Fossilization in the iron oxide–hydroxide mineral goethite led to a high-fidelity preservation of not only the exterior, but of the pharyngeal plate and a neuropile in the cephalothorax. The discovery of the fossil supports the molecular-based hypothesis that the Late Oligocene/Early Miocene radiation of astioid genera occurred in Australasia. Modern Asian genera then would be the result of northward migrations from Australia rather than a movement in the other direction. Biogeographically, the Miocene Simaetha fits within the predicted bioclimatic distribution of the genus today, though the bioclimatic requirements of the fossil species are now found in eastern Queensland rather than in central New South Wales. Simaetha, it seems has retained its original bioclimatic profile for 15 Myr, even though climatic and ecological conditions in Australia have changed significantly. The fossil record now shows the independent evolution of modern genera during the Early Miocene in at least five different salticid lineages on two continents. These salticid radiations occurred at a time of planet-wide, rapid climatic and ecological change.