West Coast garter snake

T. validus is found in the Mexican states of Baja California Sur, Chihuahua, Guerrero, Jalisco, and Sonora.[2]

T. validus is viviparous.[2]

There are four subspecies of T. validus which are recognized as being valid, including the nominate subspecies.[2]

• Mexican Pacific Lowlands garter snake (T. v. celaeno) (Cope, 1861)
• T. v. isabelleae (Conant, 1953)
• T. v. thamnophisoides (Conant, 1961)
• T. v. validus (Kennicott, 1860)

Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Thamnophis.

The subspecific name isabelleae is in honor of the American wildlife artist Isabelle Hunt Conant, the wife of the American herpetologist Roger Conant.[3]

• Boulenger GA (1893). Catalogue of the Snakes in the British Museum (Natural History). Volume I., Containing the Families ... Colubridæ Aglyphæ, part. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I-XXVIII. (Tropidonotus validus, pp. 237–238).
• Conant R (1953). "Three New Water Snakes of the Genus [Natrix] from Mexico". Natural History Miscellanea (126): 1–9. (Natrix valida isabelleae, new subspecies, pp. 7–9).
• Conant R (1961). "A New Water Snake from Mexico, with Notes on Anal Plates and Apical Pits in Natrix and Thamnophis ". American Museum Novitates (2060): 1-22. (Natrix valida thamnophisoides, new subspecies, pp. 2–12, Figure 1).
• Cope ED (1861). "Notes and descriptions of new and little known species of American Reptiles". Proc. Acad. Nat. Sci. Philadelphia 12: 339–345. (Tropidonotus celaeno, new species, p. 341).
• Kennicott R (1860). "Descriptions of New Species of North American Serpents in the Museum of the Smithsonian Institution, Washington". Proc. Acad. Nat. Sci. Philadelphia 12: 328–338. (Regina valida, new species, pp. 334–335).