Widespread mitochondrial DNA haplotypes of Pteroptyx spp. across present–day river systems in Southeast Asia and their historical dispersal through ancient river networks

Estuarine fireflies from the genus Pteroptyx are widely distributed in Southeast Asia and famous for their nightly displays of bioluminescence by adult fireflies congregating or lekking on mangrove trees. Pteroptyx fireflies also offer insights into the history of the region, as their distribution in many of the isolated rivers they now inhabit are likely a product of dispersal via palaeorivers that formed in Southeast Asia during the Pleistocene. Here, we report the presence of widespread cytochrome oxidase subunit I ( cox1 ) haplotypes among populations of Pteroptyx spp. in estuaries throughout Southeast Asia and suggest possible dispersal routes for these haplotypes vis-à-vis the Siam and Malacca River systems. Separately, reconstruction of the haplotype tree from the cox1 gene indicated that the ancestors of Pteroptyx asymmetria, Pteroptyx bearni, Pteroptyx malaccae, Pteroptyx tener , and Pteroptyx valida either had a Thai, Bornean, or Peninsular Malaysian origin. Previous reconstructions of the phylogenetic and network trees of Pteroptyx sp. did not consider the presence of identical mitochondrial DNA haplotypes in their datasets, and the role palaeorivers had on their dispersal. The perspectives reported here aim to guide future taxonomic, phylogenetic and phylogeographic work on Pteroptyx fireflies in Southeast Asia. ### Competing Interest Statement The authors have declared no competing interest.