tegu, (genus Tupinambis), any of about seven large, carnivorous, tropical South American lizards of the family Teiidae. The background colour of most species is black. Some have yellow, reddish, or white bands across the back, whereas others have broad lines extending down the body with irregular markings on the top surface. The scales of the tegu are small, square, and arranged in regular rings around the body. This large lizard has a streamlined body shape with a long tail and powerful legs. Most species are roughly 1 metre (3 feet) long; however, one species, the black-and-white tegu (T. merianae), reaches 1.3 metres (about 4 feet) in total length. Like other teiids, the tegu uses its tongue and Jacobson’s organ (a chemoreceptor organ located on the roof of its mouth) to detect and discriminate chemical cues associated with prey and other individual lizards.
Tegus occur in a wide variety of habitats, including the Amazon Rainforest, savannas, and deciduous semiarid thorn forests. Even though these are large, conspicuous lizards, two new species, T. longilineus and T. quadrilineatus, were described as late as the mid-1990s, and additional undescribed species are known to exist. Several species have been heavily exploited commercially, primarily in Argentina, for their hides—a source of high-quality leather used for making shoes and purses. Tegus are considered a delicacy in parts of South America and are eaten locally. They are also popular in the commercial pet trade, and the release of the black-and-white tegu by pet merchants and owners in Florida since the early 2000s led to their classification as an invasive species there.