Crotalus willardi is a venomous pitviper species found in the southwestern United States and Mexico. It is the most recent rattlesnake species to be discovered in the United States. Its specific name is in honor of its discoverer, Professor Frank C. Willard. Five subspecies are currently recognized. The Arizona ridge-nosed rattlesnake is the state reptile of Arizona.
Description: C. willardi is a rather small rattlesnake with all subspecies measuring one to two feet in length. Color patterns are generally a dark/brown base with pale or white horizontal striping, but vary slightly between subspecies. The distinctive ridges along each side of its nose, which are a series of upturned scales, are unique to its species and are the origin of its name.
Habitat: C. willardi is rarely found outside habitats of high elevation. Wooded mountain ranges, primarily in the southwest, are where this reclusive species is found. Each subspecies range is limited to select mountain ranges, making human encounters rare events.