Molecular phylogeny of the genus Apatrobus (Coleoptera: Carabidae: Patrobinae) in western Japan

We performed a molecular phylogenetic analysis of the ground beetles Apatrobus (Carabidae), endemic to Japan, using the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear 28S rRNA (28S) genes. We focused on the species divergence in Kyushu, Shikoku and western Honshu and used 15 of 19 species and three populations with undetermined species in the DNA analysis. The gene trees showed that, of the Apatrobus species studied, A. hayachinensis Nakane from northern Honshu was not included in the monophyletic group of the other Apatrobus species and likely to be of a different genus. Divergence time estimation suggested that Apatrobus species excluding A. hayachinensis diverged 5.2 million years ago and the subsequent divergence of species occurred during the Pliocene and Pleistocene. In each of the main islands, Kyushu, Shikoku and Honshu, two or more distinct lineages occurred and all species had restricted distribution areas, suggesting that ancient dispersal and vicariance among the three main islands resulted in the nested biogeographical pattern of species distribution.