Home

Collared lizards of the genus Crotaphytus are among the most colorful lizards in North America. They get their name from the pair of black collars that circle the back of the neck. All of the genus Crotaphytus have these collars, though they vary in size and shape between the different species. Collared lizards are characterized by a large head, skinny neck, and a large body with a long skinny tail. There are two forms of collared lizards, the collaris form and the insularis form. The collaris form has a blunt snout, a round tail, and green or blue coloration in males. Both sexes have black oral melanin in which they use during the defense behavior of mouth gaping. The insularis form has a long snout and a wedge shape tail. They lack the oral melanin. Males lack the bright coloration but have enlarged inguinal patches. Axtell (1972) suggested that the insularis forms are primitive character states. The rear limbs of collared lizards are longer than the front limbs, giving them the appearance of a small T-rex. There is strong sexual dimorphism between male and female collared lizards. The maximum size in males is between 111mm to 125mm depending on the species. The maximum size for females is 97mm to 108mm, again depending on the species. Males are the more colorful of the sexes. Their size and coloration evolved due to their territorial behavior and their reliance on vision. Collared lizards were first described in Edwin James' account of Expedition to the Rocky Mountains in 1823. Thomas Say, a member of that expedition, collected and described them as Agama collaris. In 1842, Holbrock placed collared lizards in the new genus Crotaphytus. Until recently, leopard lizards were also included in this genus. They have since been placed in the genus Gambelia. In 1989 Frost and Etheridge put these two genera in the iguanian family Crotaphytidae. With the discovery of new species, scientific names of collared lizards have changed many times. Currently they have been divided into at least eight or nine species.