Delimitation of the widely distributed Palearctic species (Hemiptera, Heteroptera, Miridae): insights from molecular and morphological data.

Species delimitation presents a significant challenge in biology, particularly in systematics. Here, an integrative approach is employed to assess the species boundaries of widely distributed Palearctic species. Due to their diversity, wide distribution, and the absence of comprehensive morphological and molecular data for most species, revising is both daunting and time-consuming. Our study focuses on detailed examinations of male and female genitalia, coupled with phylogenetic analyses based on two mitochondrial markers (cytochrome c oxidase subunit I and 16S rRNA) and species delimitation analyses. Eight species with wide distributions are reviewed, Reuter, 1904 is synonymized with (Jakovlev, 1889), and a lectotype for Reuter, 1904 is designated. Morphological and molecular data effectively distinguish all species, revealing distinct clades and relationships. Notably, and form a well-supported clade, while and share a lineage with Nearctic species. and are morphologically similar and form a distinct clade in all phylogenies. Species delimitation analyses confirm the separation of all studied species, and genetic distances suggest the potential existence of cryptic species within and . This study highlights the advantages of integrative taxonomy in delimiting species with intricate and relatively recent phylogeographic histories.