Canyon spotted whiptail

The largest whiptail lizard in the United States (up to 140 mm or 5.5" from snout to vent). It is a slim, reddish brown lizard with a long, thin tail, and a slim, pointed snout. The head, neck, and tail are reddish orange. Young animals have six or seven distinct, light colored stripes on the neck and body. As males age the stripes often begin to break up into spots and additional spots begin to emerge from the dark spaces between the stripes. In some populations large adult males are spotted and lack stripes entirely. The scales on the body are small and granular. The scales on the tail are large, keeled, and rectangular. The scales on the belly are large, smooth, and rectangular. The scales on top of the head are large, smooth, and plate-like. The similar looking Sonoran Spotted Whiptail is smaller, retains its striped pattern into adulthood, and usually does not have an orange tail. The similar looking Red-backed Whiptail has distinct orange coloration on the lower back (but not on the sides), does not have reddish-orange coloration on the neck, and has blue tinting on the limbs. (information from http://www.reptilesofaz.org/ )