The genus Bombina is divided into 3 groups: Korean, European and Indo-Malayan. The Korean and European species form a sister taxon (having a single immediate ancestor). B. microdeladigitora and B. fortinuptialis belongs to the Indo-Malayan clade. Because there is very little difference in the DNA of the two previous mentioned species, it has been suggested that they be reassigned as subspecies of B. maxima. The hypothesis that B. orientalis was the sister group of B. maxima was rejected. It is likely there may be enough difference that they will not be able to breed with B. orientalis; and even if they could it would not benefit either species.

Yu, G., Yang, J., Zhang, M., and Rao, D. (2007). ''Phylogenetic and systematic study of the genus Bombina: New insights from molecular data.'' Journal of Herpetology, 41(3), 365-377.
Zheng, Y., Fu, J. and Li, S. (2009). ''Toward understanding the distribution of Laurasian frogs: A test of Savage’s biogeographical hypothesis using the genus Bombina.'' Molecular Phylogenetics and Evolution, 52(1), 70-83.