Revision of the Oriental <i>Roxasella</i> leafhopper group: phylogeny, morphological evolution, biogeography, and description of 14 new species

Abstract The leafhopper subtribe Paraboloponina inhabits the tropics of the Old World, with many species geographically limited to specific islands within the Malay Archipelago or to mainland South-East Asia. Thus, its distribution offers valuable insights into the biogeographic patterns and evolutionary forces shaping the area. To clarify the phylogenetic relationships of this group, a comprehensive study was conducted involving 70 morphological characters scored for 39 exemplars, including 19 representatives of Roxasella and 19 from 13 allied genera and an undescribed genus. Employing maximum parsimony and maximum likelihood methodologies, analyses of both morphological traits and mitochondrial COI sequences resulted in well-resolved trees, which showed that Roxasella, as previously defined, is polyphyletic. Ancestral character state reconstruction via the Bayesian binary method revealed some homoplasy in diagnostic morphological features traditionally used to diagnose taxa. Reconstruction of biogeographic history suggests that the Roxasella lineage originated in mainland South-East Asia before expanding to the Malay Archipelago, including Borneo, Java, Sulawesi, and the Philippines. Restricting Roxasella to a monophyletic group primarily associated with Borneo necessitates a redefinition of the genus. As a result, three previously assigned species are transferred to two newly established genera, Auranticopona and Philipona. Two novel monotypic genera, Paraphysipona and Sabahanus, are described, each representing unique evolutionary branches. Furthermore, 12 new species of Roxasella are described with four new combinations.