Phylogenetics, Molecular Species Delimitation and Geometric Morphometrics of All Reddish-Brown Species in the Genus Lewis, 1887 (Coleoptera: Erotylidae: Tritomini).

To date, five species of reddish-brown have been described, but their highly similar body color and other phenotypic traits make accurate taxonomy challenging. To clarify species-level taxonomy and validate potential new species, the cytochrome oxidase subunit I () was used for phylogenetic analysis and the geometric morphometrics of elytron, pronotum, and hind wing were employed to distinguish all reddish-brown species. Phylogenetic results using maximum likelihood and Bayesian analyses of sequences aligned well with the current taxonomy of the species group. Significant KP divergences, with no overlap between intra- and interspecific genetic distances, were obtained in species. The automatic barcode gap discovery (ABGD), assemble species by automatic partitioning (ASAP), and generalized mixed Yule coalescent (GMYC) approaches concurred, dividing the similar species into eight molecular operational taxonomic units (MOTUs). Geometric morphometric analysis using pronotum, elytron, hind wing shape and wing vein patterns also validated the classification of all eight species. By integrating these analytical approaches with morphological evidence, we successfully delineated the reddish-brown species of into eight species with three new species: sp. nov., sp. nov., and sp. nov. Furthermore, we documented the first record of in China. This study underscores the utility of an integrative taxonomy approach in species delimitation within and serves as a reference for the taxonomic revision of other morphologically challenging beetles through integrative taxonomy.