Mexican beaded lizard
Mexican beaded lizard[1] | |
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At Zürich Zoologischer Garten | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Family: | Helodermatidae |
Genus: | Heloderma |
Species: | H. horridum
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Binomial name | |
Heloderma horridum (Wiegmann, 1829)
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Synonyms[4] | |
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The Mexican beaded lizard (Heloderma horridum) is a
Threatened throughout its range by overcollection and habitat loss, it is a CITES protected species. The Guatemalan beaded lizard (H. charlesbogerti) is one of the rarest lizards in the world, with a wild population of fewer than 200.
Taxonomy
The beaded lizards have one close living relative, the Gila monster (H. suspectum), as well as many extinct relatives in the Helodermatidae, whose genetic history may be traced back to the Cretaceous period. The genus Heloderma has existed since the Miocene Epoch, when H. texana ranged over most of North America.[5] Because the helodermatids have remained relatively unchanged morphologically, they are occasionally regarded as living fossils.[6] Although the beaded lizards appear closely related to the monitor lizards (varanids) of Africa, Asia, and Australia, the wide geographical separation and unique features not found in the varanids indicate the beaded lizards are better placed in a separate family.[7]
The species was first described in 1829 by Arend Wiegmann as Trachyderma horridum, but he renamed it Heloderma horridum six months later.[8] Its 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.
Species
The four subspecies of beaded lizards, elevated to full species in 2013, are:[9]
Species | Taxon author | Subsp.* | Common name | Geographic range |
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H. alvarezi | Bogert and Martin del Campo, 1956 | 0 | Chiapan beaded lizard | Mexico: northern Chiapas to extreme northwestern Guatemala |
H. charlesbogertiT | Campbell and Vannini, 1988
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0 | Guatemalan beaded lizard | Guatemala: the Motagua Valley |
H. exasperatum | Bogert and Martin del Campo, 1956 | 0 | Rio Fuerte beaded lizard | Mexico: Rio Fuerte, Rio Mayo, southern Sonora, northern Sinaloa, western Chihuahua and the Sierra Madre Occidental |
H. horridumT | (Wiegmann, 1829) | 0 | Mexican beaded lizard | Mexico: southern Sinaloa to Oaxaca |
Description
Adult beaded lizards range from 57 to 91 cm (22 to 36 in) in length. They are substantially larger than the Gila monster, which only reaches lengths of 30 to 56 cm (12 to 22 in). The snout-to-vent length of a beaded lizard averages 33 to 48 cm (13 to 19 in). The average body mass of an adult beaded lizard is 800 g (1.8 lb), about 45% heavier than the average mass of a Gila monster, with large specimens exceeding 2,000 g (4.4 lb). Maximum weight known is 4,000 g (8.8 lb)
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
Habitat and range
Beaded lizards are found in the Pacific drainages from southern
The Mexican beaded lizard H. horridum is found in Mexico, from
Ecology
Diet
The beaded lizard is a specialized
Venom
The venom glands of the beaded lizard are modified salivary glands located in the reptile's lower jaw. Each gland has a separate duct leading to the base of its grooved teeth. When biting, the beaded lizard hangs on its victim and chews to get its venomous saliva into the wound. Although its jaw grip is strong, its unsocketed teeth are easily broken off at their bases. The beaded lizard's venom is a weak hemotoxin, and although human deaths are rare, it can cause respiratory failure. It consists of a number of components, including L-amino acid oxidase, hyaluronidase, phospholipase A, serotonin, and highly active kallikreins that release vasoactive kinins. The venom contains no enzymes that significantly affect coagulation. Almost all documented human bites (eight in the past century) have resulted from prodding captive lizards with a finger or bare foot.[17]
While invertebrates are essentially immune to the effects of this venom, effects on vertebrates are more severe and varied. In mammals such as rats, major effects include a rapid reduction in carotid blood flow followed by a marked fall in blood pressure, respiratory irregularities, tachycardia, and other cardiac anomalies, as well as hypothermia, edema, and internal hemorrhage in the gastrointestinal tract, lungs, eyes, liver, and kidneys. In humans, the effects of bites are associated with excruciating pain that may extend well beyond the area bitten and persist up to 24 hours. Other common effects of bites on humans include local edema (swelling), weakness, sweating, and a rapid fall in blood pressure. Beaded lizards are immune to the effects of their own venom.[18]
Some compounds in its venom have been shown to have pharmacological properties relating to the possible treatment of
Reproduction
The beaded lizard becomes sexually mature as early as 3 years, and typically mates during summer months. In captivity, breeding generally follows the same pattern, but successful breeding can occur any month of the year. Males engage in
Young lizards are seldom seen. They are believed to spend much of their early lives underground, emerging at 2–3 years of age after gaining considerable size.[22]
Conservation
The beaded lizard is surrounded by myth and superstition in much of its
The beaded lizard is protected by Mexican law under the category A (Threatened), and it dwells within the range of several protected areas.[23] In Guatemala, it is protected by national legislation, and part of its range is within protected areas. It is listed on Appendix II of CITES.[22]
It is estimated that fewer than 200 lizards remain in the
References
- ^ "Heloderma horridum". Integrated Taxonomic Information System. Retrieved 20 September 2008.
- . Retrieved 12 November 2021.
- ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
- ^ Heloderma horridum . Retrieved through: Interim Register of Marine and Nonmarine Genera on 17 June 2022.
- ^ a b c Cogger (1992) p. 156
- ISBN 978-0-253-34366-6.
- ISBN 978-0-7137-2357-1.
- ^ Wiegmann, A.F.A. (1829). "Über die Gesetzlichkeit in der geographischen Verbreitung der Saurier". Isis von Oken. 22 (3–4): 418–428.
- ^ http://www.redlist-arc.org/Article-PDFs/Special%20Mexico%20Issue_ARC_7(1)_74-96_low_res.pdf Archived 2013-10-23 at the Wayback Machine Reiserer & al., 2013, Taxonomic reassessment and conservation status of the beaded lizard, Heloderma horridum (Squamata: Helodermatidae)
- ^ Beck, D. D. (2005). Biology of Gila monsters and beaded lizards (Vol. 9). Univ of California Press.
- ^ Grzimek, Dr. H.C. Bernhard. 1975. Animal Life Encyclopedia. Volume 6 Pgs. 321-322 and 151-152. Van Nostrand Reinhold Company.
- ^ a b c d Angeli, Steven (2005). "Beaded Dragon" (PDF). Reptile Care. 9 (1): 36–39. Retrieved 2008-09-22.
- ^ a b c Beck 2005, pp. 35–36
- ^ JSTOR 1564340.
- JSTOR 1935656.
- ^ Applegate, Robert (1991). Northern California Herpetological Society's Conference on Captive Propagation and Husbandry of Reptiles and Amphibians. Sacramento, California: Northern California Herpetological Society. pp. 39–44.
- ISBN 978-0-87666-567-1.
- ^ Beck 2005, p. 44
- ^ Beck 2005, pp. 41–61
- PMID 1313797. Retrieved 2008-09-21.
- S2CID 5293453.
- ^ a b c d "Protecting the Guatemalan Beaded Lizard". The Nature Conservancy in Guatemala. The Nature Conservancy. 2007. Archived from the original on January 5, 2011. Retrieved 2010-09-14.
- ^ a b "CONSIDERATION OF PROPOSALS FOR AMENDMENT OF APPENDICES I AND II" (PDF). Fourteenth meeting of the Conference of the Parties. Convention on International Trade in Endangered Species of Wild Flora and Fauna. 2007. Archived from the original (PDF) on 2009-02-19. Retrieved 2008-09-22.
Further reading
- Ariano-Sánchez, Daniel (2008). "Envenomation by a wild Guatemalan beaded lizard Heloderma horridum charlesbogerti". Clinical Toxicology. 46 (9): 897–899. S2CID 22173811.
- Ariano, D. y G. Salazar. 2007. Notes on the Distribution of the Endangered Lizard, Heloderma horridum charlesbogerti, in the Dry Forests of Eastern Guatemala: An Application of Multi-criteria Evaluation to Conservation. Iguana 14(3): 152–158.[1]
- Ariano, D. 2006. The Guatemalan beaded lizard: Endangered inhabitant of a unique ecosystem. Iguana 13(3): 178–183. [2]
- Ariano-Sánchez, D.; Muñoz-Alons, A.; Marquez, L.C.; Acevedo, M. (2014). "Heloderma horridum". . Retrieved 12 November 2021. Listed as Vulnerable (VU A2cd v2.3)
- Beck, Daniel D. (2005). Biology of Gila Monsters and Beaded Lizards (Organisms and Environments). University of California Press. p. 247. ISBN 978-0-520-24357-6.
- Berkow, Robert (1992). The Merck Manual (16th ed.). Merck Research Laboratories. ISBN 978-0-911910-16-2.
- ISBN 978-0-8317-2786-4.
External
- IRCF's Guatemalan Beaded Lizard Conservation Project
- Mexican Beaded Lizard at the LA Zoo
- Mexican Beaded Lizard at the Saint Louis Zoo
- Protecting Guatemalan beaded lizards: Conservation Heloderma