The Beaded Lizard is a venomous species found principally in Mexico and southern Guatemala. It and its close relative, the Gila monster are the only lizards known to have evolved an overt venom delivery system. Its venom has been found to contain several enzymes useful for manufacturing drugs in the treatment of diabetes. The Guatemalan beaded lizard is one of the rarest lizards in the world, with a wild population of fewer than 200. The species was first described in 1829 by Arend Wiegmann. Its specific name, horrĭdum, is the Latin word meaning rough or rude.