Remarks concerning Certain Western Garter Snakes of the Thamnophis elegans Complex

Abstract

Thamnophis elegans biscutatus is a valid subspecies of the Klamath Lakes basin distinguishable from its nearest relatives by size, number of scale rows, head shape, and especially by habits and habitat. Thamnophis errans of the Sierra Madre Occidental in Mexico is a distinct species, though closely related to T. elegans vagrans, and perhaps to T. e. hueyi of Baja California. In attempting to prepare species-accounts of garter snakes for the Catalogue of American Amphibians and Reptiles sponsored by the Society for the Study of Amphibians and Reptiles, I have been puzzled and intrigued by several taxonomic problems that require clarification. My own original field studies and museum studies of Thamnophis were carried on mainly in the period 1933-1936. Obviously, in the period of almost half a century that has elapsed, garter snake classification has made notable progress, with new material, new methods and techniques and more intensive studies, all providing greater insight into the relationships within this complex group. However, some of the facts that were revealed from 15 to more than 40 years ago and that still have important bearing on classification, seem to have been overlooked or forgotten. Hence, I offer the present contribution without having much new data concerning the snakes themselves. The present report is concerned with two separate problems. The first concerns the validity of the subspecies Thamnophis elegans biscutatus endemic to the Klamath Lakes basin, and its relationships to the neighboring allopatric subspecies T. e. elegans, T. e. vagrans, and T. couchi hydrophilus. The second involves the status of the Mexican garter snake Thamnophis errans-whether it is a distinct species or intergrades with T. elegans vagrans of the southwestern United States. VALIDITY OF THAMNOPHIS ELEGANS BISCUTATUS