Mexican beaded lizard beaded lizard under the Convention on International Trade in Endangered Species as an Appendix I animal, making it illegal to export the species. Mexican beaded lizard The Mexican beaded lizard ("Heloderma horridum") is a species of lizard in the family Helodermatidae, one of the two species of venomous beaded lizards found principally in Mexico and southern Guatemala. It and its congener (member of the same genus) the Gila monster ("Heloderma suspectum") are the only lizards known to have evolved an overt venom delivery system. The Mexican beaded lizard is larger than the Gila monster, with duller coloration, black with yellowish
Mexican beaded lizard with large specimens exceeding . Maximum weight known is Although males are slightly larger than females, the lizards are not sexually dimorphic. Both males and females are stocky with broad heads, although the males' tend to be broader. The beaded lizard's scales are small, beadlike, and not overlapping. Except for the lizard's underside, the majority of its scales are underlaid with bony osteoderms. Their base color is black and marked with varying amounts of yellow spots or bands, with the exception of "H. alvarezi", which tends to be all black in color. The beaded lizard has a short tail which