|Based on multigene data, Kubatko et al. (2011. Systematic Biology 60: 393–409) recommended elevating Sistrurus c. catenatus to full species. Complicating matters, Holycross et al. (2008. Copeia 2008: 421–424) had discovered that S. c. tergeminus was subsumed by S. c. catenatus because the type locality of the latter is within the range of the former. Consequently, S. tergeminus was not a valid name and the specific epithet for the eastern form would have been S. massassaugus. A petition to the ICZN (Crother et al. 2011. Bulletin of Zoological Nomenclature. 68: 271–274) elicited an opinion by the ICZN (2013. & Bulletin of Zoological Nomenclature. 70: 282–283) retaining the names S. catenatus and S. tergeminus by designating neotypes for both species. Common names for the relevant taxa are Eastern Massasauga (S. catenatus), Western Massasauga (S. tergeminus), Prairie Massasauga (S. t. tergeminus), and Desert Massassauga (S. t. edwardsii).