Snake, that is.
It’s a rare event when I plan a herping excursion to an area seeking specific forms and actually manage to find at least one of them. The Kisatchie Corn Snake shown here recently managed to somewhat relieve that nemesis.
Long known to herpetological hobbyists as the “Kisatchie Corn Snake” from its prevalence in west-central Louisiana’s Kisatchie National Forest, this form has remained taxonomically controversial over the years. Until relatively recently, the Kisatchie Corn has generally been regarded as simply a drably colored population of the usually garish Corn Snake (Pantherophis guttatus), although some have suggested that it is in fact an intergrade population between eastern (P. g. guttatus) and western (P. g. emoryi, the Great Plains Rat Snake) races of a more widely distributed single Corn Snake species.
Adding to the controversy is the recent description of this form as a full species, Slowinski’s Corn Snake (Pantherophis slowinskii) by Frank T. Burbrink (2002 [PDF]). Burbrink’s data is based largely upon mitochondrial DNA sequencing and a strongly held conviction that large rivers – especially those such as the Mississippi – should constitute evolutionary barriers, despite the well-known fact that all snakes can swim.
While Burbrink’s mtDNA analysis did reveal a clade indigenous to the west-central Louisiana area but closely related to the eastern group, his findings are diminished by the fact that he had no tissues from other areas where this form allegedly occurs in much closer proximity to the very similar Great Plains Rat Snake (P. emoryi), such as southern Arkansas, SE Oklahoma, and eastern Texas (Burbrink, in fact, states that P. slowinskii occurs no further south in Texas than the Brazos River, which we now know it does, perhaps expressing his fixation with rivers again).
At any rate, this turn of events reinforces my contention that one should avoid rushing to adopt the latest taxonomic innovations. Burbrink’s paper is only a single test of this hypothesis. Proper scientific methodology requires that sound theories (in the scientific sense) should not be synthesized from only a single investigation. Indeed, in such controversial situations, adoption of taxonomic change could – and should – await further research that would either validate or refute Burbrink’s conclusions.
Despite all of this, both of the organizations purporting to seek standardization of common names and taxonomic nomenclature in American herps (Center for North American Herpetology and the SSAR-HL-ASIH Committee [PDF]) immediately accepted Burbrink’s alteration of the taxonomy in this group (it should be pointed out that Burbrink is a member of the latter group – perhaps not the best tactic in avoiding the appearance of conflict of interest).
As for my personal opinion, I have no trouble in recognizing this distinct population taxonomically, however I feel that it is currently more appropriate at the subspecies level (i.e., Pantherophis guttatus slowinskii) than as a full species.
Ironically, though, the category of subspecies is currently out of favor among reptile taxonomists, some even curiously arguing that it is “uninformative.” Composed mostly of molecular systematists enslaved by the dogmas of cladistics, modern phylogeneticists apparently ignore the subspecies category simply because their espoused doctrines and methodologies lack techniques to deal with it.
Burbrink, Frank T. 2002. Phylogeographic analysis of the corn snake (Elaphe guttata) complex as inferred from maximum likelihood and Bayesian analyses. Molecular Phylogenetics and Evolution 25 (2002): 465-476.