Argentine black and white tegu

Argentine black and white tegu
Specimen of Salvator merianae in the Buenos Aires Zoo
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Reptilia
Order:	Squamata
Suborder:	Lacertilia
Infraorder:	Scincomorpha
Family:	Teiidae
Genus:	Salvator
Species:	S. merianae
Binomial name
Salvator merianae A.M.C. Duméril & Bibron, 1839
Synonyms[2]
Salvator merianae A.M.C. Duméril & Bibron, 1839 Teius teguixim — Gray, 1845 Tupinambis teguixin — Boulenger, 1885 Tupinambis merianae — Dirksen & De la Riva, 1999 Salvator merianae — Harvey et al., 2012

The Argentine black and white tegu (Salvator merianae), also called the Argentine giant tegu,^[1] is the largest species of tegu lizard.^[3] 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.

Tegus fill ecological niches similar to those of monitor lizards, and are an example of convergent evolution.

Etymology

The specific name, merianae, is in honor of German-born naturalist Maria Sibylla Merian.^[4]

An adult female black and white tegu.

Description

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.^[5]

Warm-bloodedness

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.^[6] 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,^[7] but also supports the hypothesis that the initial selective benefit for endothermy in birds and mammals was reproductive ^[8][9]

Diet

Tegus are omnivorous. Juvenile Argentine tegus in the wild have been observed to eat a wide range of invertebrates, including insects, spiders, and snails. They also eat fruits and seeds. As they grow they become more predatory and the protein content of their diet rises. They may seek out eggs from other reptiles and from birds' nests, and will eat small birds and other vertebrates. In adulthood Argentine tegus continue to eat insects and wild fruits, and it is assumed that such components include desirable or essential nutrients.

In captivity, tegus commonly are fed high protein diets that include raw or cooked flesh, eggs, insects, and small rodents. The inclusion of fruit in the diet is recommended, though many captive tegus do not readily eat fruit.^[10] However, there is evidence that, as in most husbandry of carnivores, it is good practice to cook most of the egg in the diet, so as to denature the protein avidin, that occurs in the albumen. Raw avidin immobilises biotin, so excessive feeding of raw eggs may cause fatal biotin deficiency.^[11]

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.

Taxonomy

The two prominent loreal scales between the eye and nostril of this black and white tegu, plus its round pupil, identify it as belonging to the genus Salvator.

In 1839 this species of tegu was originally described as Salvator merianae. However, beginning in 1845 and continuing for 154 years, it was confused with Tupinambis teguixin, and was considered a synonym of that species. In 1995 it was again given species status as Tupinambis merianae because subsequent studies had shown that it and the gold tegu, Tupinambis teguixin, are distinct from each other. In 2012 the Argentine black and white tegu was reassigned to the resurrected genus Salvator as Salvator merianae.^[12]

S. merianae 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 or incompetent pet dealers sometimes pass off gold tegus as black and white tegus.

S. merianae and T. teguixin can be distinguished by skin texture and scale count:

• S. merianae has two loreal scales between eye and nostril.
• T. teguixin has only a single loreal scale between eye and nostril.
• S. merianae has round pupils whereas Tupinambis species have reniform pupils.

See also

• Blue tegu
• Gold tegu
• Tegu
• Teius
• Teius teyou

References

1. 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.
2. "Salvator merianae ". The Reptile Database. www.reptile-database.org.
3. www.wildherps.com
4. Beolens B, Watkins M, Grayson M. (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Tupinambis merianae, p. 175).
5. http://www.uco.es/organiza/servicios/publica/az/php/img/web/17_12_32_15NotaRendimientoBasso.pdf pp2
6. 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.
7. Hutchison, V.H.; Vinegar, A (1966). "Thermoregulation in a brooding female Indian Python, Python molurus bivittatus". Science. 11 (3711): 694–695.
8. 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.
9. Farmer, C.G. (2003). "Reproduction: The Adaptive Significance of Endothermy". American Naturalist. 162 (6): 826–840. doi:10.1086/380922.
10. Kiefer, Mara C., and Ivan Sazima. (2002). "Diet of Juvenile Tegu Lizard Tupinambis meriamae (Teiidae) in Southeastern Brazil." Amphibia-Reptilia 23: 105-108. Eco Evo. Koninklijke Brill NV. Web. 9 Dec. 2013.
11. Gerald Hoff (6 December 2012). Diseases of Amphibians and Reptiles. Springer Science & Business Media. pp. 643–. ISBN 978-1-4615-9391-1.
12. HARVEY, MICHAEL B. UGUETO, GABRIEL N. GUTBERLET, RONALD L. Jr. Review of Teiid Morphology with a Revised Taxonomy and Phylogeny of the Teiidae (Lepidosauria: Squamata) Zootaxa 3459: 1–156 (2012)

Further reading

• Duméril AMC, Bibron G (1839). Erpétologie générale ou Histoire naturelle complète des Reptiles. Tome cinquième [Volume 5]. Paris: Roret. viii + 854 pp. (Salvator merianae, new species, pp. 85–90). (in French).

External links

A black and white tegu seen in Florianópolis, Santa Catarina, Brazil.

• Care for Argentine Black and White Tegus