Pantherophis emoryi

Using genome-scale data, Myers et al. (2020) found support for three previously recognized species: P. guttatus, P. slowinskii, and P. emoryi. Subsequently, Marshall et al. (2021) demonstrated support for the same
three taxa but also found P. emoryi could further be divided into the subspecies P. e. meahllmorum and P. e. emoryi, and also suggested that P. slowinskii be considered a subspecies of P. emoryi. Nicholson (2025) note that P. e. slowinskii is sister taxon to the other proposed subspecies of P. emoryi, and that all are distinct evolutionary lineages. They recognize P. slowinskii as a species, and recognize that P. emoryi consists of two taxa. See Burbrink et al. (2024) for reanalysis and evaluation of Marshall et al. (2021) demonstrating species status. Also see Burbrink et al. (2022).

Burbrink (2002) used cytochrome b sequences to examine phylogenetic relationships among E. guttata populations. He identified three partitions of E. guttata and recognized them as species using evolutionary species criteria: (1) Elaphe guttata (red corn snake) (eastern partition ), (2) Elaphe emoryi (Great Plains rat snake) (western partition), and (3) Elaphe slowinskii (Slowinski's corn snake) (central partition). One specimen (Hidalgo County, Texas) of the central partition (based on cytochrome b characteristics) was located outside the presumed geographic area and habitat identified for other members of that partition. Burbrink also found no support for recognition of the nominal subspecies intermontanus and meahllmorum as distinct taxa.

The range extends from southwestern Illinois, Missouri, southern South Dakota, and southeastern Colorado southward to San Luis Potosi and Veracruz, and through most of Texas, with a disjunct population in eastern Utah and western Colorado (Conant and Collins 1991, Burbrink 2002).

This species is represented by a large number of occurrences (subpopulations).

No major threats are known. Locally, habitat destruction has reduced or eliminated some populations, but this species tolerates moderate levels of habitat alteration such as those associated with rural ranching activities.