Molecular phylogenetic analysis of a taxonomically unstable ranid from Sumatra, Indonesia, reveals a new genus with gastromyzophorous tadpoles and two new species

The presence of an adhesive abdominal sucker (gastromyzophory) allows tadpoles of certain species of anurans to live in fast-flowing streams. Gastromyzophorous tadpoles are rare among anurans, known only in certain American bufonids and Asian ranids. To date, Huia sumatrana, which inhabits cascading streams, has been the only Sumatran ranid known to possess gastromyzophorous tadpoles. In the absence of thorough sampling and molecular barcoding of adults and larvae, it has remained to be confirmed whether other Sumatran ranid species living in similar habitats, i.e., Chalcorana crassiovis, possesses this larval type. Moreover, the taxonomic status of this species has long been uncertain and its taxonomic position within the Ranidae, previously based exclusively on morphological characters, has remained unresolved. To study the diversity and relationships of these frogs and to establish the identity of newly collected gastromyzophorous tadpoles from Sumatra, we compared genetic sequences of C. crassiovis-like taxa from a wide range of sites on Sumatra. We conducted bayesian and maximum likelihood phylogenetic analyses on a concatenated dataset of mitochondrial (12S rRNA, 16S rRNA, and tRNA^val) and nuclear (RAG1 and TYR) gene fragments. Our analyses recovered C. crassiovis to be related to Clinotarsus, Huia, and Meristogenys. The DNA barcodes of the gastromyzophorous tadpoles matched adults from the same sites. Herein, we provide a re-description of adult C. crassiovis and propose "C. kampeni" as a synonym of this species. The molecular evidence, morphological features, and distribution suggest the presence of two related new species. The two new species and C. crassiovis together represent a distinct phylogenetic clade possessing unique molecular and morphological synapomorphies, thus warranting a new genus.