Thorpe et al. (2007) used mitochondrial DNA sequences and morphological data to analyse the systematics of the Russell's viper (Daboia russelii)  complex in Asia. Mitochondrial DNA sequence analysis revealed a deep split between populations east and west of the Bay of Bengal, corresponding to the two morphologically defined taxa revealed by Wüster et al. (1992). Since these two clusters of populations are both clearly diagnosable and allopatric, Thorpe et al. recognise two species within the complex, Daboia russelii being the western (India, Sri Lanka, Pakistan, Nepal) and Daboia siamensis the eastern (Myanmar, Thailand, Cambodia, China, Taiwan, Indonesia) form. Despite its wide and fragmented distribution, the halotypes of D. siamensis are very similar, suggesting recent divergence of the present-day populations of the species. The lack of correspondence between mtDNA phylogeny and the syndrome of envenoming from the different populations led the authors to suggest that the extraordinarily variable effects of the venom of the species may be the result of allele fixation during bottlenecks rather than adaptation for different diets.

• Thorpe, R.S., C.E. Pook & A. Malhotra (2007) Phylogeography of the Russell's viper (Daboia russelii) complex in relation to variation in the colour pattern and symptoms of envenoming. Herpetological Journal 17: 209-218.
• Wüster, W., S. Otsuka, A. Malhotra & R.S. Thorpe (1992) Population systematics of Russell's viper: a multivariate study. Biological Journal of the Linnean Society, 47: 97-113. pdf