Mainland diversification and recent island lineages in the reduviid genus <i>Tapirocoris</i> : an integrative taxonomic framework with four new species

The assassin bug genus Tapirocoris Miller, 1954 (Hemiptera: Reduviidae: Harpactorinae: Dicrotelini) is distributed in southern China and adjacent regions. However, gradual morphological variation among its members has long complicated species delimitation and obscured the understanding of their phylogenetic relationship and evolutionary history. Here, we apply an integrative taxonomic framework to revise the classification of Tapirocoris and to reconstruct its spatio-temporal diversification history. Based on mitochondrial COI DNA barcode sequences from 94 specimens collected across 26 localities, multiple species-delimitation methods and phylogenetic inference consistently recovered seven well-supported evolutionary lineages, including three previously known species and four newly described species: T. hainanensis Zhao & Cai, sp. nov., T. rufus Zhao & Cai, sp. nov., T. taiwanensis Zhao & Cai, sp. nov., and T. yuensis Zhao & Cai, sp. nov. Geometric morphometric analyses further confirmed that these lineages are morphologically diagnosable. Divergence time estimation may indicate an early Miocene crown origin of Tapirocoris (∼21.48 Ma), and discrete phylogeographic reconstruction is consistent with repeated range shifts between the South China hilly region and the Yunnan-Guizhou Plateau, forming a mainland diversification backbone. Subsequent directional dispersal events likely contributed to the emergence of insular endemic species in Hainan and Taiwan during the Pleistocene. These interpretations are based primarily on mitochondrial COI data and would benefit from further validation using multilocus or nuclear genomic datasets. In addition, we provide an updated key to the species of Tapirocoris and a world catalogue of the tribe Dicrotelini, establishing practical taxonomic resources and a broader systematic framework for future research.