THE GROUND BEETLES OF THE TRIBUS TRECHINI (CARABIDAE) ON THE SOUTHERN KURIL ISLANDS

This article is devoted to the inventory of ground beetles of the tribe Trechini on the southern Kuril Islands. Until the beginning of the XXI century, only one species of tribe was noted from the islands. As a result of our survey in 2008-2018 on the islands of Kunashir, Shikotan, Yuri, and Polonskogo, 764 specimens of ground beetles of the tribe Trechini were collected and studied, belonging to four species from two genera: Blemus discus (Kunashir Island), Trechus nakaguroi (Kunashir Island), T. dorsistriatus (Kunashir, Shikotan, Polon skogo and Yuri islands) and T. nigricornis (Kunashir and Yuri islands). To clarify their taxonomic status, type specimens of T. alexandrovi, T. dorsistriatus, T. nigricornis, Epaphius arsenjevi, and E. plutenkoi, as well as 475 specimens of these species from other parts of their ranges, were studied as comparative materials. Based on the study of this material, the following taxonomic changes were proposed: T. dorsistriatus laferi ssp. nov.; Blemus discus alexandrovi, stat. rest.; T. nigricornis, stat. resurr.; T. nakaguroi sachalinensis, stat. nov.; T. nigricornis arsenjevi, stat. nov.; Epaphius arsenjevi = Epaphius plutenkoi, syn. nov. The holotype of T. nigricornis was designated. Blemus discus alexandrovi has been recorded for the first time in the fauna of the Kuril Islands. The features of distribution and ecology of all species on the surveyed islands are discussed. Current ly, B. discus is found only on the west coast of Kunashir Island, suggesting a recent colonisation of this island. Trechus nakaguroi inhabits only the mountainous dark coniferous forests of the northern Kunashir, which indicates a relict distribution of this species. Trechus dorsistriatus is the most abundant species of Trechini, inhabiting the most diverse biotopes on all the islands of the South Kurile. Trechus nigricornis is an inhabitant of moss mires in river floodplains. Unlike the specimens of this species from the mainland and Hokkaido, all specimens of T. nigricornis from the Southern Kuril Islands are wingless; we associate this with the impos sibility of flying in the cold and foggy climate of the Kuril Islands. The proposed hypothesis on the formation of the Trechini fauna of the South Kurile is based on the geological youth of the Kuril Islands, which makes it necessary to take into account that by the time ground beetles colonised their ranges, most of the currently existing Trechini groups already existed, and their modern distribution was largely determined by climate and landscape changes in the Quaternary period. The compiled identification key includes the four species of the South Kuril fauna and Trechus ephippiatus, repeatedly erroneously indicated from Kunashir Island.

Automated summary

This article summarizes the inventory of ground beetles of the tribe Trechini on the southern Kuril Islands, with four species identified and taxonomic changes proposed based on specimen studies. Each species has different ecological and distribution characteristics on the surveyed islands, possibly influenced by climate and landscape changes.