SUBSPECIES AND DISTRIBUTION: The only living relative closely related to the Gila monster is the Beaded Lizard, Heloderma horridum, often all called the Mexican Beaded Lizard. There are four subspecies, one properly named the Mexican Beaded Lizard (Heloderma horridum horridum). The other three are the Rio Fuerte Beaded Lizard (Heloderma horridum exasperatum), the Rio Grijalva Beaded Lizard (Heloderma horridum alvarezi, aka the Chiapan or Black Beaded Lizard), and the Motagua Valley Beaded Lizard (Heloderma horridum charlesbogerti), all found in western Mexico (mostly coastal) except the latter which occurs only as a small, isolated, endangered population in the Motagua Valley of Guatemala. Unlike their relatives to the north, these are not desert lizards. Their preferred habitat is subtropical/tropical dry forest.

ANATOMY & BEHAVIOR: The two species of Heloderma differ significantly in several anatomical ways. Like all helodermatid lizards, beaded lizards have a distinctive skin with a pebbly texture that comes from bony nodules (osteoderms) embedded within the their scaly skin. In color, these animals are typically yellow and black or gray. Beaded lizards are longer and lankier than Gila monsters and are better suited to an arboreal life style. They legs are proportionally longer and they are excellent climbers. Although they usually spend most of their time on the forest floor, they sometimes utilize tree holes for shelter and will climb shrubs and trees in search of bird eggs and chicks for food. Curiously, beaded lizards have pink tongues, while those of their close cousins are blackish in color. Heloderma tongues are forked and serve as chemo-receptors, used to "taste" their environment and hunt for prey.

CONSERVATION CONCERNS: Although widely distributed along the western coast of Mexico, habitat preferred by beaded lizards has been said to be the most threatened forest type in the world. Death on roads and loss of their tropical/subtropical dry forest habitat to slash-and-burn agriculture and production of charcoal for cooking fuel are the most serious threats. In southern Mexico, vast tracts of land are being cleared for Agave plantations, a cash crop used in making tequila. In Mexico, many farmers and ranchers fear beaded lizards (escorpion) and regularly kill them on sight.

EDUCATION: During our travels, we found an excellent environmental education program in place at Zoo Miguel Alvarez del Toro (ZooMAT) in Tuxtla Gutierrz, Chiapas, Mexico. In both indoor and outdoor classroom settings, children learn about biodiversity and environmental conservation to help them develop an appreciation for their rich natural heritage. While we were there, herpetologist Antonio Ramirez gave young children the opportunity to touch and learn about their Rio Grijalva Beaded Lizard, Heloderma horridum alvarezi. We had the opportunity to photograph one of these lizards on the edge of Sumidero Canyon in the Valley of Rio Grijalva, Chiapas.