Widespread amphibians are frequently impacted by incorrect species assignments and inaccurate taxonomic labelling in open databases and published studies, leading to confusion regarding species boundaries and missing information for population trends at the ecozone level. We examined three genera in the family Dicroglossidae (Fejervarya, Hoplobatrachus and Quasipaa) across the Indomalaya and Palearctic ecozones, where unresolved species boundaries and the introduction of exotic populations are significant issues. Alternative to conventional phylogeny, we employed the Bayes Factor Delimitation method and nested sampling to assess 18 comparative delimitation models for 15 verified species in GenBank, using 4,044 bp unlinked multilocus data from 487 individual Asian Dicroglossids across both ecozones. Our best-supported model delineated 17 clades across three genera, highlighting Fejervarya as the genus with the shallowest clade assemblages, with two clades within each of the F. kawamurai, F. multistriata, and F. limnocharis species complexes, all diverging below 3.70 Mya in the Northern Indomalaya and Southeastern Palearctic. Through adjusted ecological niche modelling with species delimitation data, we verify that precipitation of the driest month, elevation, and mean diurnal temperature range, are key variables influencing the distribution of F. kawamurai and F. multistriata in mainland East Asia. Cross validation using call analysis supported significant differences in call durations and intervals between F. kawamurai [Clade II] and F. multistriata [Clade II] in their overlapping range in the eastern Yangtze River Basin indicated the existence of subspecies boundaries even in the absence of physical barriers and validated the presence of F. multistriata along the central coast of China, i.e. Shanghai. Our findings also showed the clustering of the southern Palearctic Fejervarya clade, including the population in the Jiangsu Plains, within the Yangtze group of F. kawamurai, and delineated the northern limit of F. multistriata in the vicinity of the Huai River.
