The Aruba Rattlesnake, known locally as the Cascabel, is one of the world’s rarest species of rattlesnake and occurs only on Aruba.
Estimates suggest that there are less than 230 adults left in the wild.
I have treated it as a distinct species: Crotalus unicolor, but sometimes it is classified as a subspecies of the South American Rattlesnake: Crotalus durissus unicolor.

Arikok National Park, Aruba, 16 December 2006