Taxonomic Status of Some Neotropical Garter Snakes (Genus Thamnophis)
Taxonomic status of some neotropical garter snakes (genus Thamnophis) by Robert G. Webb, Bull. Southern California Acad, of Sci. 81(1):26-40. Study of the black-necked garter snake, Thamnophis cyrtopsis, and of three other taxa of garter snakes from south of the Isthmus of Tehuantepec, Mexico, indicates that 1) T. cyrtopsis collaris (Jan) occurs in the Mexican state of Chiapas and in Guatemala, 2) T. cyrtopsis var. fulvus (Bocourt) is a valid species occurring in Chiapas, Guatemala, Honduras, and El Salvador, 3) T. sumichrasti cerebrosus Smith has been incorrectly referred to the species sumichrasti and cyrtopsis, and seems to have affinities with T. marcianiis, and 4) T. sumichrasti salvini Smith, Nixon and Smith is a synonym of T. cyrtopsis collaris.
Webb, Robert G.
"Taxonomic Status of Some Neotropical Garter Snakes (Genus Thamnophis),"
Bulletin of the Southern California Academy of Sciences:
Available at: http://scholar.oxy.edu/scas/vol81/iss1/3