until 2002, 10 subspecies of "s. undulatus" were recognized:, but re-evaluation showed paraphyly between the subspecies. these were reclassified as four distinct evolutionary species (the three new species being "s. consobrinus", "s. tristichus", and "s. cowlesi"). the narrowed redefinition of "s. undulatus" has been suggested to still contain two subspecies divided by the appalachian mountains. none is currently formally recognized.