Formerly considered a full species, Trimorphodon biscutatus vilkinsonii is presently regarded as a subspecies of T. biscutatus based on morphological data compiled from eight male specimens from southeastern Arizona and southwestern New Mexico; these specimens were thought to be intermediate between the currently recognized T. b. lambda (from Sonora and Arizona) and T. b. vilkinsonii (from Chihuahua and Texas). We performed univariate and multivariate statistical analyses of a morphological data set compiled for T. b. vilkinsonii, T. b. lambda, and specimens collected from the intermediate zone. Our analyses indicate that T. b. vilkinsonii is clearly distinct from T. b. lambda. Several characters, such as blotch width and interblotch distance, allowed more than 95% of specimens of both taxa to be classified properly. Our data also confirm that specimens sampled from the intermediate zone should be considered T. b. lambda. We find the T. b. vilkinsonii populations represent a separate, distinct lineage, and we elevate this taxon to species level.

The Herpetologists' League
2003
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