Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Iguanid Classification

©1996, 2002 Melissa Kaplan

Iguania
Your green iguana (Iguana iguana) is related to some 700 other species of iguanids, including the desert iguana (Dipsosaurus) and chuckawalla (also spelled chuckwalla, Sauromalus) of the American Southwest deserts; the spiny-tailed, or black, iguana (Ctenosaura) of North and Central America; the Galápagos iguanas* (marine: Amblyrhynchus and land: Conolophus); the so-called forest chameleons or helmeted iguanas (Corytophanes) and casque-headed iguanas (Laemanctus) of Central and South America; the rock and rhino iguanas found on scattered Caribbean islands (Cyclura); even iguanids on such far flung islands as Madagascar (called swifts: Chalarodon and Oplurus) and Fiji (Brachylophus).

The family Iguanidae is wide-ranging throughout the New World, stretching from southern Canada to southern Argentina, from the Galápagos through the West Indies. The family includes four other familiar new world lizard genera: the anoles (Anolis), spiny, or fence, lizards (Sceloporous), the island-dwelling curly-tailed iguanas (Leiocephalus), and the South American swifts (Liolaemus). Iguanids may be distantly related to the Old World agamid species, which includes such lizards as the Northern African and Middle Eastern spiny-tailed, or dab, lizards (Uromastyx spp.) and the Philippine and Chinese water dragons (Physignathus spp.). Whether iguanids evolved from agamids, or agamids from iguanids, or whether they are a classic example of convergent evolution, is still a matter of debate.

The Iguaniae subfamily, while being a sometimes disputed classification, contains the large, strictly herbivorous iguanids. Other traits of these lizards include their relatively large body size and diurnal habits. All are ectotherms who behaviorally thermoregulate their body temperatures, and all lay eggs in deep burrows. They typically live in dry or rainless or essentially rainless areas, and may be subjected to seasonal unavailability of foods or seasonal swings in the nutritional content of their food sources.

Classification of the Green Iguana
Also known as: common green iguana; giant green iguana

If you are planning a trip to the Galápagos (and even if you are not)...
Along with the modern-day guide books you read, I highly recommend taking the time to read William Beebe's account of his 1923 trip to the Galápagos. Noted biologist and explorer, Beebe and a team of scientists and others, including artists, photographer, taxidermist, hunter, specimen preparers and curator to catalog everything, made a whirlwind trip to most of the islands in the archipelago. Sailing from New York on March 1, 1923, on the steam yacht Norma, the privately funded expedition returned to New York on May 16, sailing 9,000 miles. Their expedition catalogued, by photo, drawing, painting, and specimen collection and recording, material and live animals and plants for the New York Zoological Society and the American Museum.

This trip, only 88 years after Darwin's visit to Galápagos (recorded in his Diary of the Voyage of the H.M.S. Beagle, is remarkable not only for the breadth of work done in a very short time, and for the fact that, in a world where it may take years after the fact for conference proceedings to be published, within six months after their return, nearly twenty-two scientific papers were already published or nearly ready to be so. Beebe's book records their voyage of discovery and some of their adventures while doing so, in a beautifully written work. The fact that we now know that some of their early suppositions were incorrect (such as the blowing of steam by the marine iguanas), these do no lessen the pleasure of this work and the world they found and so ably recorded.

Beebe, William. Galápagos: World's End. Originally published 1924; reprint edition published 1988. 520 pages, 114 illustrations. Dover Publications. Available through: Amazon.com, Amazon.co.uk, B&N.com, and Booksamillion.com

Darwin, Charles. Voyage of the Beagle: Journal of Researches into the Natural History and Geology of the Countries Visited during the Voyage of H.M.S. Beagle. Reprint edition published 2001. 496 pages; illustrated. Random House, Inc. Available through: Amazon.com, Amazon.co.uk, B&N.com, and Booksamillion.com

For up-to-date reptile classification information, please visit the EMBL Reptile Database.

For more information on many Iguanine species: Animal Diversity Web

For additional information on iguana classification, please visit Jennifer Swofford's Iguana Pages.

For a complete survey of the Iguana iguana literature, please visit Adam Britton's Iguana Bibliography site.

Sources:

Burghardt, Gordon, A. Stanley Rand. 1982. Iguanas of the World: Their Behavior, Ecology and Conservation. Noyes Publishing, Park Ridge, NJ.

TIGR Reptile Database: Iguania