Biotectonic analysis of Tasmania-New Zealand connections with special reference to Coleoptera

New Zealand and Tasmania share 274 coleopteran genera, most of which are represented by adventive species that are shared between both areas (155 spp.) or have adventive species exclusive to either area (47 genera). Most of the 19 intrinsically shared species are widespread aquatics. Among the genera and higher taxa, we identified 9 taxa endemic to Tasmania – New Zealand (T-NZ) and 9 taxa shared between Tasmania, New Zealand, and southeastern Australia (T-seA-NZ). Time trees, biogeographic studies, and relevant fossil data are not extensive, but indicate that most beetle lineages present in Tasmania and New Zealand extended back into the Cretaceous. For example, the tenebrionid subfamily Zolodininae, known by two extant monotypic genera distributed in Tasmania and New Zealand, is represented by an extinct species present in Burmese amber dated to 99Ma. We conclude that T-seA-NZ lineages may have been originally distributed on a continental block composed of VanDieland (seAustralia/Tasmania/ South Tasman Rise) and the Challenger Plateau/South Zealandia which remained contiguous until the Late Cretaceous separation of Zealandia from Gondwana. The VanDieland block had been geographically isolated from both East Antarctica and Australia as early as the Late Jurassic or Early Cretaceous by rifts associated with the opening of the Southern Ocean between Australia and East Antarctica and spreading along the West Antarctic Rift System (WARS). Some T-seA distributions may be as recent as the Pleistocene when Tasmania and southeast Australia were reconnected during the LGM. The remaining T-NZ groups are relict.