First record of Carabus insulicola in Tomakomai, Hokkaido, and identification of source population by DNA analysis

Abstract

Carabus insulicola Chaudoir, 1869 is a Japanese endemic ground-beetle species with a major geographic range from central to northern Honshu. In Hokkaido it had previously been found in Hakodate and Bibai, but here we report a new record from Tomakomai City. We found the species in two isolated urban forests, whereas we did not find it in the large suburban forests. mtDNA analysis of the NADH dehydrogenase subunit 5 (ND5) in two male individuals revealed that nucleotide sequences of the two specimens were identical with the one in the southern Tohoku District, not the one from the northern Tohoku District ̶ just across a narrow strait from Hokkaido. This result strongly suggests that the population in Tomakomai City was introduced from Honshu by human activity. Introduction of and colonization by the species are likely facilitated by: i) active movement of people and goods between the southern Tohoku Distinct and Tomakomai; and ii) the species' preference for forest edges and open habitats, and ability to inhabit urban forests.