Mexican beaded lizard generic name "Heloderma" means "studded skin", from the Ancient Greek words "hêlos" (ἧλος)—the head of a nail or stud—and "dérma" (δέρμα), meaning skin. Its specific name, "horrĭdum", is the Latin word meaning rough or rude. The four subspecies of beaded lizard, elevated to full species in 2013, are: Adult beaded lizards range from in length. They are substantially larger than the Gila monster, which only reaches lengths of . The snout-to-vent length of a beaded lizard averages . The average body mass of an adult beaded lizard is , about 45% heavier than the average mass of a gila monster,
Isthmian alligator lizard Isthmian alligator lizard The isthmian alligator lizard ("Gerrhonotus rhombifer") is a species of lizard of the Anguidae family. "G. rhombifer" is found in both Costa Rica and Panama. Unlike many lizards near its habitat, individuals have lateral folds. They give birth to live young. "Gerrhonotus rhombifer" had not been seen for fifty years, prior to being rediscovered in 2000 near Golfito, and is one of the rarest species of lizard in Costa Rica. "G. rhombifer" is a broad-headed, long-bodied lizard, which is similar to "Diploglossus monotropis". An adult measures from in total length, with the tail making up approximately two-thirds