The Helodermatidae or beaded lizards are a small family of lizards endemic to North America today, but formerly more widespread in the ancient past. Traditionally, the Gila monster and the Mexican beaded lizard were the only species recognized, although the latter has recently been split into several species.
Heloderma is a genus of toxicoferan lizards that contains five species, all of which are venomous. It is the only extant genus of the family Helodermatidae.
The Mexican beaded lizard 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 the other members of the same genus, including the Gila monster, 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 bands. As it is a specialized predator that feeds primarily upon eggs, the primary use of its venom is still a source of debate among scientists. This venom has been found to contain several enzymes useful for manufacturing drugs in the treatment of diabetes, and research on the pharmacological use of its venom is ongoing.
Ctenosaura pectinata is a species of moderately large lizard in the family Iguanidae. The species is native to western Mexico.
Ctenosaura bakeri, also known as the Utila spiny-tailed iguana, Baker's spinytail iguana, swamper or wishiwilly del suampo, is a critically endangered species of spinytail iguana endemic to the island of Utila, one of the Islas de la Bahía off the coast of Honduras in the Caribbean.
The Campeche spiny-tailed iguana is a species of lizard in the family Iguanidae. The species is native to southeastern Mexico and adjacent Guatemala.
Ctenosaura palearis, commonly known as the Motagua spiny-tailed iguana, is a species of spiny-tailed iguana endemic to the Motagua Valley in Guatemala.
The Anguimorpha is a suborder of squamates. The group was named by Fürbringer in 1900 to include all autarchoglossans closer to Varanus and Anguis than Scincus. These lizards, along with iguanians and snakes, constitute the proposed "venom clade" Toxicofera of all venomous reptiles.
Ctenosaura similis, commonly known as the black iguana or black spiny-tailed iguana, is an iguanid lizard native to Mexico and Central America. It has been reported in some Colombian islands in the Caribbean Sea and Pacific Ocean, and has been introduced to the United States in the state of Florida. The largest species in the genus Ctenosaura, it is commonly found in areas such as grasslands and forests.
Cyclura is a genus of lizards in the family Iguanidae. Member species of this genus are commonly known as "cycluras" and only occur on islands in the West Indies. Rock iguanas have a high degree of endemism, with a single species or subspecies originating on an individual island.
The Gila monster is a species of venomous lizard native to the Southwestern United States and the northwestern Mexican state of Sonora. It is a heavy, slow-moving reptile, up to 56 centimetres (22 in) long, and it is the only venomous lizard native to the United States. Its venomous close relatives, the four beaded lizards inhabit Mexico and Guatemala. The Gila monster is sluggish in nature, so it is not generally dangerous and very rarely poses a real threat to humans. However, it has a fearsome reputation and is sometimes killed despite the species being protected by state law in Arizona.
Ctenosaura acanthura, is a species of iguanid lizard found in eastern Mexico and extreme western Guatemala. The standardized English name is the Mexican spiny-tailed iguana. Confusingly however, an earlier edition of standardized names for Mexican herpetofauna called Ctenosaura acanthura the northeastern spinytailed iguana and applied the name Mexican spinytailed iguana to Ctenosaura pectinata, which was called the western spiny-tailed iguana in the second edition. It has also been referred to as the Veracruz spiny-tailed iguana and Gulf Coast spiny-tailed iguana. It is an egg laying species that is mostly herbivorous and a moderately large lizard commonly growing over one meter in total length.
The Motagua Valley thornscrub ecoregion is located in the Motagua valley in eastern Guatemala. Surrounded by mountains and receiving relatively little precipitation, the valley is one of the driest in Central America and is characterized by thorn scrub vegetation. It covers an area of 2330 km2 and belongs to the deserts and xeric shrublands biome, as defined by the World Wildlife Fund.
Abronia campbelli, commonly known as Campbell's alligator lizard, is species of critically endangered arboreal alligator lizard in the family Anguidae. Abronia campbelli is endemic to eastern Guatemala.
Rhadinella xerophila is a very rare snake endemic to the seasonally dry forests and thornscrub of the Middle Motagua Valley in Guatemala. This snake is characterized by its orange auburn head and its small size. This species is related to the group of Rhadinella that have dark dorsal coloration, which mostly or completely obscures a pattern of longitudinal striping characteristic of the majority of species of Rhadinella. This species has dark gray, almost black, dorsal coloration with barely discernible slightly darker striping. Top of the head is mostly blackish with irregular auburn-orange markings on the internasals, prefrontals, frontal, parietals, loreals, postoculars, temporals, and two ultimate supralabials. Most conspicuous features are an orange-auburn Y-shaped marking along frontal-parietal and interparietal sutures, followed by an orange nuchal collar. The closest relative of the new species, based on morphological similarities, appears to be Rhadinella pilonaorum, which occurs in a relatively mesic habitat of pine-oak forest located about 90 km southwest from the type-locality of the new species. It has been recorded only at Heloderma Natural Reserve, El Arenal, Zacapa, Guatemala.
The Rio Fuerte beaded lizard is a venomous species of beaded lizard in the family Helodermatidae. It is found in the tropical forests and shrublands of western Mexico, specifically around the Rio Fuerte and Rio Mayo basins. It is often found in or near abandoned mammal burrows and sources of water.
Heloderma alvarezi, the Chiapan beaded lizard or black beaded lizard, is a species of lizard of the Helodermatidae family. It is found in Mexico and Guatemala.
