Neotropical rattlesnake (Crotalus durissus) - Most of Central and South America has only one species of rattlesnake, the tropical rattlesnake or cascabel. It is one of the most dangerous of all rattlesnakes, with strongly neurotoxic elements in its venom that produce paralysis of both voluntary and involuntary muscles. The stripes on its neck are a quick way of distinguishing it from our western diamondback rattlesnake (Crotalus atrox).