Argentine black and white tegu
|Argentine black and white tegu|
|Specimen in Buenos Aires Zoo|
(Duméril and Bibron, 1839)
Salvator merianae Duméril & Bibron, 1839
The Argentine black and white tegu (Salvator merianae), also called the Argentine giant tegu, is the largest species of tegu lizard. They are an omnivorous species which inhabits the tropical rain forests, savannas, and semi-deserts of east and central South America.
Argentine tegus have unusually high intelligence. It has been observed and recorded that some will regularly and clearly seek out human affection, just as a dog or cat might. Some form a strong attachment to their keeper. Some have been reported to come on command; they can also be house-broken.
Like many other reptiles, Argentine tegus go into brumation (a form of hibernation) in autumn when the temperature drops. They exhibit a high level of activity during their wakeful period of the year.
As household pets
Argentine tegus make amenable pets, as they tend to become attached to their owners and are generally quite docile as adults. They are intelligent and can even be house-broken.
A healthy tegu can live for 15 to 20 years in the wild, and possibly even longer in captivity. However, as with most reptiles, if they are not handled regularly they will show more aggressive behaviour.
Salvator merianae has recently been shown to be the first known partially warm-blooded lizard, having a temperature up to 10 °C (18 °F) higher than the ambient temperature. However, unlike true endotherms such as mammals and birds, these lizards only display temperature control during their reproductive season (September to December), and for that reason are said to possess seasonal reproductive endothermy. Because convergent evolution is one of the strongest lines of evidence for the adaptive significance of a trait, the discovery of reproductive endothermy in this lizard not only complements the long known reproductive endothermy observed in some species of pythons, but also supports the hypothesis that the initial selective benefit for endothermy in birds and mammals was reproductive 
As hatchlings, they have an emerald green color from the tip of their snout to midway down their neck with black markings. The emerald green becomes black a couple of months after shedding.
Adult males are much larger than the females and can reach 3 feet (92 cm) in length at maturity. They may continue to grow to lengths of 4 – 4.5 feet (120 to 140 cm).
The females are much smaller, but may grow up to 3 feet in length, from nose to tail. They have beaded skin and stripes running down their body. Adult females can reach a weight of 2.5 – 7 kg.
Tegus are omnivorous lizards. In the wild, juvenile Argentine tegus have been observed eating a diet consisting primarily of insects, spiders, wild fruits and seeds. As tegus outgrow their juvenile state they begin to move towards a higher protein diet, frequently scavenging eggs from other reptiles, and even eating small birds. However, even adult Argentine tegus continue eating insects and wild fruits as they grow older, as these foods hold essential nutrients to the tegu.
In captivity, tegus are generally fed high protein diets including things like: raw or cooked chicken, turkey, eggs, insects, small rodents, and fruits. Many captive tegus have an unwillingness to eat fruit. However, there is also some discrepancy as to whether or not the ingestion of unfertilized bird eggs can have an adverse effect on a Tegu’s ability to produce biotin.
These tegus were originally known as Tupinambis teguixin, but were reclassified because subsequent studies showed that they and the gold tegu are distinct from each other. The Argentine black and white tegu was reclassified as Salvator merianae.
The species is called the "Argentine black and white tegu" to distinguish it from the "Colombian black and white tegu", which is another name for the gold tegu. Unscrupulous pet dealers will sometimes pass off gold tegus as black and white tegus.
T. merianae and T. teguixin can be distinguished by skin texture and scale count:
- T. merianae have two pairs of loreal scales between the eyes and the nostrils.
- T. teguixin have only a single pair of loreal scales.
- T. merianae also have a smoother skin texture.
- Embert, D., Fitzgerald, L. & Waldez, F. (2010). "Salvator merianae". IUCN Red List of Threatened Species. Version 2014.3. International Union for Conservation of Nature. Retrieved 22 January 2015.
- Tattersall, G. J.; Leite, C. A. C.; Sanders, C. E.; Cadena, V.; Andrade, D. V.; Abe, A. S.; Milsom, W. K. (2016-01-22). "Seasonal reproductive endothermy in tegu lizards". Science Advances 2 (1): e1500951. doi:10.1126/sciadv.1500951.
- Hutchison, V.H.; Vinegar, A (1966). "Thermoregulation in a brooding female Indian Python, Python molurus bivittatus". Science 11 (3711): 694–695.
- Farmer, C.G. (2000). "Parental Care: The Key to Understanding Endothermy and Other Convergent Features in Birds and Mammals". American Naturalist 155 (3): 326–334. doi:10.1086/303323.
- Farmer, C.G. (2003). "Reproduction: The Adaptive Significance of Endothermy". American Naturalist 162 (6): 826–840. doi:10.1086/380922.
- http://www.uco.es/organiza/servicios/publica/az/php/img/web/17_12_32_15NotaRendimientoBasso.pdf pp2
- Kiefer, Mara C., and Ivan Sazima. "Diet of Juvenile Tegu Lizard Tupinambis meriamae (Teiidae) in Southeastern Brazil." Amphibia-Reptilia 23 (2002): 105-08. Eco Evo. Koninklijke Brill NV. Web. 9 Dec. 2013.