Summary
The terrestrial amphipod Puhuruhuru patersoni (Amphipoda: Talitridae) was discovered on sub-Antarctic Macquarie Island in 1992. The species is only known to naturally occur on New Zealand's South Island and some associated offshore islands. The possible routes by which the species was introduced to Macquarie Island have previously been considered based on morphology and historic activities between New Zealand and Macquarie Island. Here, we sampled across the known range for P. patersoni and generated mtDNA COI data for these specimens to investigate the likely origin of the Macquarie Island incursion. Our results showed high genetic diversity across the native range and substantially lower genetic diversity on Macquarie Island. Additionally, our phylogenetic reconstructions suggested that the source of the introduction to Macquarie Island is likely to have been from the southern region of New Zealand's South Island.