New fossil stoneflies (Plecoptera: Arctoperlaria) from Australia testify ancient dispersal across Pangea

Abstract

The stonefly suborders Arctoperlaria and Antarctoperlaria reflect the current division of the diversity of this insect order between the Northern and Southern Hemispheres. However, there are several exceptions to this pattern, the most notable being the family Notonemouridae, which is phylogenetically deeply subordinate within the northern Arctoperlaria, but distributed in South Africa, South America, and Australia. Various hypotheses have been proposed regarding the circumstances of their dispersal to the south. Some estimated their origin as relatively recent, with long-distance dispersal to the southern continents in the Late Cretaceous or early Paleogene. On the other hand, fossils of Notonemouridae have been dated to the Middle Jurassic, proving the lineage is very ancient. However, all known notonemourid fossils originate from Asia and the timing of their dispersal to the south cannot be precisely estimated. Here we report new fossil stoneflies from the Late Jurassic Talbragar Fish Beds, Australia, described as Talbragaria australisgen. et sp. nov. and attributed to Notonemouridae. This finding represents the first fossil evidence of the northern suborder Arctoperlaria in the Southern Hemisphere, and confirms the north-to-south dispersal of Notonemouridae across Pangea prior to the continental break-up.