This is a study of the populations of Thamnophis sirtalis that occur in Chihuahua, Mexico, and the adjoining U.S. state of New Mexico. Reference is made to previous studies dealing with geographical and systematic relationships. Additional data are provided for the New Mexico subspecies (dorsalis), and the relationship of T. s. parietalis to the New Mexico population is discussed. The Chihuahua population is described as a new subspecies.
Tanner, Wilmer W.
"Status of Thamnophis sirtalis in Chihuahua, Mexico (Reptilia: Colubridae),"
Great Basin Naturalist: Vol. 48
, Article 7.
Available at: http://scholarsarchive.byu.edu/gbn/vol48/iss4/7