Comments: Keratin biochemistry suggests that New World members of genus Agkistrodon may not be monophyletic (if such genera as Deinagkistrodon and Calloselasma are recognized as valid) (Campbell and Whitmore 1989). See Chiasson et al. (1989) for information on scale morphology and its implications concerning relationships among Agkistrodon and closely related genera. According to Crother et al. (2008), evidence from MtDNA data suggests that this single species may be composed of multiple independently evolving lineages not concordant with traditional subspecific designations (Guiher and Burbrink, pers. comm.).