Genetic divergences of South and Southeast Asian frogs: a case study of several taxa based on 16S ribosomal RNA gene data with notes on the generic name Fejervarya

To elucidate the genetic divergences of several Asian frog taxa, the mitochondrial 16S rRNA gene (16S) sequences of 81 populations across 6 Asian countries were analyzed. In total, 109 haplotypes were found, and the concept of a 3% difference in 16S sequence corresponding to species threshold was applied to define candidate amphibian species, for which corroborating evidence, such as morphology, ecological characteristics, and/or nuclear gene data, is required. Polypedates leucomystax, Hylarana chalconota, and Hylarana sp. from Chantaburi, Maelippet Siberut, and Langkawi Island, respectively, correspond to 3 candidate species and H. erythraea from Malaysia/Thailand represents a possible candidate species. Hylarana cf. nicobariensis from Muara Siberut, Amolops larutensis from Gombak, and Microhyla okinavensis from Ishigaki Island showed divergences from the topotypic specimen, all suggesting a relevant candidate species. Microhyla heymonsi from Malaysia and M. ornata from 2 regions (Mudigere and Talapu) in India did not fit any congeneric species based on available 16S data, suggesting 3 possible candidate species in total. Two lineages of Duttaphrynus melanostictus from Malaysia denote 2 possible candidate species. Consequently, this study indicates the occurrence of 6 candidate and 6 possible candidate species, and argues that the generic allocation of the Fejervarya–Minervarya–Zakerana complex needs to be studied in detail.