Integrative Taxonomy and Biogeographical History of the Subgenus Abea , With Synonymy of Micronialoe (Coleoptera: Carabidae: Pterostichus )

The ground beetle subgenera Abea Morita and Micronialoe Park, Kwon & Lafer are a small group within the genus Pterostichus , endemic to Japan and Korea. In this study, we apply an integrative approach combining molecular and morphological evidence to resolve their taxonomic problems at subgeneric and specific levels. Phylogenetic reconstruction of Pterostichus and related genera using 28S rRNA supported Micronialoe as a junior synonym of Abea . Examination of more than 250 specimens of Korean Abea revealed eight distinct morphotypes defined by male genitalia, despite high external morphological similarity. Phylogenetic analysis using a concatenated dataset of 28S rRNA and COI recovered seven major clades within Korean Abea , supporting four new species: Pterostichus subterraneus sp. nov., P. bifoveolatoides sp. nov., P. mixtus sp. nov., and P. multispinulosus sp. nov. Genetic divergence analyses under the Kimura 2‐parameter model revealed a barcoding gap in 28S rRNA (0.9%–1.0%) but overlap in COI (1.0%–1.5%). Traditional morphometric analyses of 190 specimens, based on two raw measurements and 13 ratios, did not clearly resolve species boundaries for most species. These results underscore the importance of integrating molecular evidence and male genital morphology for species delimitation within Abea . Our phylogenetic framework further provided insights into subterranean adaptation and genital evolution. Additionally, time‐calibrated analyses and ancestral area reconstruction suggested dispersal of Abea and related subgenera from China to Korea and Japan. Together, these findings provide insight into the systematics and biogeography of Pterostichus ground beetles.