The Argentine black and white tegu (Salvator merianae), also commonly called the Argentine giant tegu, the black and white tegu, the huge tegu, and lagarto overo in Spanish is a species of lizard in the family Teiidae. The species is the largest of the “tegu lizards”. It is an omnivorous species which inhabits the tropical rain forests, savannas, and semi-deserts of eastern and central South America.
Tegus are sometimes kept as pets. They are notable for their unusually high intelligence and can also be house-broken. Like other reptiles, tegus go into brumation 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.
As a hatchling, Salvator merianae has an emerald green color from the tip of its snout to midway down its neck, with black markings. The emerald green becomes black several months after shedding. As a young tegu, the tail is banded yellow and black; as it ages, the solid yellow bands nearest to the body change to areas of weak speckling. Fewer solid bands indicates an older animal. A tegu can drop a section of its tail as a distraction if attacked. The tail is also used as a weapon to swipe at an aggressor; even a half-hearted swipe can leave a bruise.
Tegus are capable of running at high speeds and can run bipedally for short distances. They often use this method in territorial defense, with the mouth open and front legs held wide to look more threatening.
Adult males are much larger than the females and can reach 3 ft (92 cm) in length at maturity. They may continue to grow to lengths of 4.0–4.5 ft (120–140 cm).
The females are much smaller, but may grow up to 3 ft in length, from nose to tail. They have beaded skin and stripes running down their bodies. Adult females can reach a weight of 2.5–7.0 kg (5.5–15.4 lb).