Product Code Database
Heloderma is a genus of lizards that contains five species, all of which are . It is the only extant genus of the family Helodermatidae.
Venom production among lizards was long thought to be unique to this genus, but researchers studying venom production have proposed many others also produce some venom, all placed in the clade Toxicofera, which includes all and 13 other families of lizards.. However, except for snakes, helodermatids, and possibly varanids, envenomation is not considered medically significant for humans.
| 1 | late Eocene (about 35 million years) |
| 2 | late Miocene (about 10 million years) |
| 3 | Pliocene (about 4.4 million years) |
| 4 | Pliocene (about 3 million years) |
The four subspecies of beaded lizards were elevated to full species in 2013.http://www.redlist-arc.org/Article-PDFs/Special%20Mexico%20Issue_ARC_7(1)_74-96_low_res.pdf Reiserer & al., 2013, Taxonomic reassessment and conservation status of the beaded lizard, Heloderma horridum (Squamata: Helodermatidae)
| H. alvarezi | Bogert and Martin del Campo, 1956 | Chiapan beaded lizard | Mexico: northern Chiapas to extreme northwestern Guatemala | |
| H. charlesbogertiT | Campbell and Vannini, 1988 | Guatemalan beaded lizard | Guatemala: the Motagua Valley | |
| H. exasperatum | Bogert and Martin del Campo, 1956 | Rio Fuerte beaded lizard | Mexico: Rio Fuerte, Rio Mayo, southern Sonora, northern Sinaloa, western Chihuahua and the Sierra Madre Occidental | |
| H. horridumT | Wiegmann, 1829 | Mexican beaded lizard | Mexico: southern Sinaloa to Oaxaca | |
| Gila monster | Cope, 1869 | Gila monster | Southwest United States, Sonora |
Members of the genus Heloderma have many extinct relatives in the Helodermatidae, whose evolutionary history may be traced back to the Cretaceous period, such as Estesia. The genus Heloderma has existed since the Miocene, when H. texana lived, and fragments of from the Gila monster have been found in late Pleistocene (8,000-10,000 years ago) deposits near Las Vegas, Nevada. Because the helodermatids have remained relatively unchanged morphologically, they are occasionally regarded as . (2026). 9780253343666, Indiana University Press. ISBN 9780253343666 Although the beaded lizards and the Gila monster appear closely related to the (varanids) of Africa, Asia, and Australia, the wide geographical separation and unique features not found in the varanids indicate they are better placed in a separate family.
The type species is Heloderma horridum, which was first described in 1829 by Arend Wiegmann. Although he originally assigned it the generic name Trachyderma, he changed it to Heloderma six months later, which means "studded skin", from the Ancient Greek words hêlos (ηλος)—the head of a nail or stud—and derma (δερμα), meaning skin.
Conrad, 2008 and Estes et al., 1988 (using morphological data) place the Helodermatidae within Varanoidea along with Lanthanotus borneensis and Varanus. However, Estes et al., 1988 understood the Helodermatidae as having split earlier from Lanthanotus and Varanus, whereas Conrad, 2008 groups them at the same branch point.
In contrast, molecular studies have identified Heloderma as being within the Anguioidea along with Anguidae and Xenosauridae, but specifically sister to Anguidae.
| Wikispecies has information related to Heloderma suspectum |
|
|
