Ultraconserved elements, DNA barcoding and morphology unravel the diversity and evolution of the Hypoponera pruinosa group (Hymenoptera: Formicidae) in Indochina and the Indo-Australian region

Abstract The genus Hypoponera Santschi, 1938, is arguably one of the most neglected ant genera in the world, kudos to its nondescript appearance and subtle interspecies differences. Despite its apparent ubiquity in the tropics, little is known about Hypoponera diversity in Southeast Asia and its neighbors, where most species remain undescribed. In this unprecedented integrative study, we used a combination of evidence from nuclear ultra-conserved elements (UCEs) and mitochondrial cytochrome oxidase subunit I (COI), alongside comparisons of morphology, to build species hypotheses and elucidate the evolution of the Hypoponera pruinosa group in Indochina and the Indo-Australian region. Based on phylogenetic analyses of 2,014 UCE loci (unphased and phased) and morphological assessments of putative molecular species units generated via 4 methods (SODA, bPTP, BPP, ≤4% COI clusters), we recognized a total of 26 nominal species in the pruinosa group, 23 of which are new to science. Reciprocal monophyly for most species was strongly supported. Divergence dating and biogeographic analyses revealed that the crown pruinosa group most likely originated in Indochina-Borneo ca. 14.9–13.8 Ma and diversified largely eastwards to neighboring areas from the Late Miocene. We identified two cases of species paraphyly, involving a novel species and the extant H. sabronae (Donisthorpe, 1941); both species were found nested within the geographically widespread H. ­pruinosa clade in UCE-based phylogenies. This study lays the groundwork for a follow-up taxonomic monograph on the pruinosa group, where new species will be formally treated and rigorously described.