Thamnophis proximus, commonly known as the western ribbon snake, is a species of garter snake in the subfamily Natricinae of the family Colubridae. The species is endemic to the western United States, Mexico, and Central America. The species has six recognized subspecies. Description T. proximus is a slender snake with a very long tail, approximately one-third of the total length of the body. Dorsally, T. proximus is blackish, brown, or olive with three light-colored stripes. Ventrally, it is greenish-white or yellowish-white. The upper labials are whitish and unmarked, contrasting with the dark top and sides of the head. Adults measure in total length (including the tail). Subspecies Six subspecies of the western ribbon snake (T. proximus) are recognized as being valid, including the nominate subspecies. T. p. alpinus – Chiapas Highlands ribbon snake T. p. diabolicus – arid land ribbon snake T. p. orarius – Gulf Coast ribbon snake T. p. proximus – orangestripe ribbon snake, western ribbon snake T. p. rubrilineatus – redstripe ribbon snake T. p. rutiloris – Mexican ribbon snake Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Thamnophis. References External links Thamnophis proximus, Illinois Natural History Survey Discover Life - Colubridae: Thamnophis proximus Encyclopedia of Life - Thamnophis proximus ITIS - Thamnophis proximus Western Ribbon Snake, Reptiles and Amphibians of Iowa. Further reading Behler JL, King FW (1979). The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. . (Thamnophis proximus, pp. 670–671 + Plates 531, 544). Conant R (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. (Illustrated by Isabelle Hunt Conant). Boston: Houghton Mifflin Company. xviii + 429 pp. + Plates 1-48. (hardcover), (paperback). (Thamnophis proximus, pp. 165–166 + Plate 23 + Map 120). Conant R, Bridges W (1939). What Snake Is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains. (With 108 drawings by Edmond Malnate). New York and London: D. Appleton-Century Company. Frontispiece map + viii +163 pp. + Plates A-C, 1-32. (Thamnophis sauritus proximus, pp. 122–123 + Plate 23, figure 69A). Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp., 47 Plates, 207 Figures.