Trans-Pecos copperhead (Agkistrodon contortrix pictigaster) - Although the copperhead occurs over most of Texas, including West Texas, it is not found in South Texas. Copperheads are related to cottonmouths and cantils. (Compare the shape of this snake's head to that of the Taylor's cantil.) Contrary to popular belief, copperheads have relatively weak venoms and fatalities from their bites are extremely rare.