Molecular phylogeographic study of the longicorn genus Xylotoles

Presented by Ethan Seow

Honours Student , The University of Sydney

Supervisors: Prof Nathan Lo (USyd), Prof Simon Ho (USyd), Dr Chris Reid (AM)

The Lord Howe Island Group (LHIG) is an insular archipelago formed by volcanic activity between 6.9 to 6.2 million years ago. Located 600km east of mainland Australia, the biota of the LHIG displays biogeographic affinities with Australia, New Zealand and New Caledonia. Xylotoles is a genus of longicorn beetle (Cerambycidae) primarily distributed in New Zealand but also described from the LHIG and Norfolk Island. It belongs to a taxonomic complex with similar longicorns from the Southwestern Pacific, such as Stenellipsis, Mesolita and Enicodes. Ethan conducted time-calibrated phylogenetic analysis on the Xylotoles based on mitochondrial and nuclear ribosomal data and demonstrate that the genus as a whole is not monophyletic, with LHIG and Norfolk Island Xylotoles forming a clade closer to Australian Stenellipsis than congeners from New Zealand.

This clade began radiating between approximately 55-32 million years ago, greatly predating the emergence of the LHIG. Ethan’s findings suggest multiple colorizations of the LHIG, either from mainland Australia or from older, now submerged islands in the Lord Howe or Tasmantid volcanic groups. Finally, Ethan describes novel species of Xylotoles and Stenellipsis from the LHIG and show that at least one c.f. Xylotoles from the LHIG belongs to the unrelated genus Sybra.