Western Racer Coluber mormon  Baird & Girard, 1852
An adult specimen from southern California Image © Michael Rochford, 2005
Taxonomic Comments:
Henry S. Fitch, William S. Brown & William S. Parker (1981 Coluber mormon, a Species Distinct from C. constrictor. Transactions of the Kansas Academy of Sciences 84(4): 196-203) provided much evidence that this taxon and C. constrictor are distinct species. Collins (1991 Herpetological Review 22(2): 42-43), in a peer-reviewed article, recommended that this previously defined, diagnosed, and allopatric taxon be recognized as a distinct species, a more conservative taxonomy than that in previous use. Collins (1997 SSAR Herpetological Circular 25: 1-40) presented this proposed change to his snake systematist group, composed of John E. Cadle, Brian I. Crother, Harry W. Greene, L. Lee Grismer, James A. MacMahon, James R. McCranie, and Samuel S. Sweet, and the majority of those individuals responding recommended that mormon be so recognized. Collins (1997) followed that recommendation. Liner (1994 SSAR Herpetological Circular 23: 1-113) considered this taxon a species distinct from C. constrictor, as proposed by Collins (1991 Herpetological Review 22(2): 42-43). Powell, Collins and Hooper (1998 A Key to the Amphibians and Reptiles of the Continental United States and Canada. University Press of Kansas, Lawrence. vi + 131 pp.) recognized this lineage as a species distinct from C. constrictor. Hammerson (1999 Amphibians and Reptiles in Colorado. Second Edition. University Press of Colorado, Niwot. xxvi + 484 pp.) considered this taxon conspecific with Coluber constrictor, despite the fact that his map clearly shows that the two diagnosed and defined lineages, contrictor and mormon, are completely isolated from each other by the Rocky Mountains. If, as Hammerson stated, the allopatric populations of Coluber in western Colorado and adjacent Utah (see the map on page 339 in Conant and Collins 1998) "tend to be intermediate between" constrictor and mormon, then they should be described as a distinct evolutionary lineage (= species), a logical (and conservative) conclusion based on the best available evidence. Continuing to recognize diagnosed and defined allopatric populations (separated by a major mountain range) as conspecific is unsupported by scientific evidence.