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Tegu

A tegu is any of several species of large, robust lizards in the family Teiidae, native to tropical and subtropical regions of Central and South America east of the Andes, and belonging primarily to the genera Salvator and Tupinambis.^[1] These diurnal, omnivorous reptiles are characterized by their strong, streamlined bodies, forked tongues for chemosensory detection, and distinctive scale patterns, with adults typically reaching lengths of 1 to 1.5 meters and weights of 4 to 10 kilograms or more.^[2]^[3] The classification of tegus was restructured in 2012 based on an analysis of 137 morphological traits, separating the southern clade into the genus Salvator (with species such as the Argentine black and white tegu, Salvator merianae, and the red tegu, S. rufescens) from the northern clade in the genus Tupinambis (including the gold tegu, T. teguixin, and six other species like T. cryptus).^[4] Salvator species tend to be larger and more omnivorous, while Tupinambis species are often more carnivorous and slightly smaller, though all exhibit ontogenetic color changes—juveniles typically feature banded patterns for camouflage that fade in adults.^[5]^[6] The S. merianae is the most widespread and commonly kept in captivity, prized for its intelligence and relative docility.^[1] Tegus are habitat generalists, occupying diverse ecosystems from rainforests and savannas to disturbed areas and urban fringes, where they burrow, climb trees, and swim proficiently.^[2] Their diet varies by age and species but generally includes fruits, seeds, insects, small vertebrates, bird eggs, and carrion, contributing to their role as ecosystem engineers through seed dispersal and soil aeration.^[3] Behaviorally, they display seasonal dormancy (estivation/brumation) during dry or cold periods, high reproductive output with clutch sizes of 20–50 eggs^[3], and partial endothermy in some species during breeding seasons.^[1]^[7] Due to their appeal in the international pet trade—with millions of skins historically exported—they face conservation pressures, and introduced populations of S. merianae and T. teguixin have established in Florida, where as of 2025 they continue to spread, posing risks as invasive predators.^[2]^[1]^[8]

Taxonomy

Etymology

The term "tegu" originates from the Tupi-Guarani language of indigenous South American peoples, specifically derived from the word "teju" or "teyú," which means "lizard."^[9]^[10] This etymology reflects the lizards' prominent role in the local fauna and culture.^[11] Early European explorers in South America, encountering these lizards during the colonial period, adopted the indigenous nomenclature to describe the species they documented. For instance, Dutch naturalist Georg Marcgrave used variations like "teju" in his 1648 Historia Naturalis Brasiliae, while Carl Linnaeus formalized "Tupinambis teguixin" in 1758, incorporating the Tupi term directly into binomial nomenclature.^[11] This adoption preserved the native linguistic heritage while integrating it into Western scientific literature. In contemporary usage, "tegu" serves as a common name encompassing several large-bodied lizard species within the Teiidae family, such as those in the genera Tupinambis and Salvator, but it is not strictly limited to them in vernacular contexts.^[12] Scientifically, however, the term is more precisely applied to these Teiidae genera, distinguishing them from other lizard groups and highlighting their phylogenetic placement within the family.^[11]

Classification

Tegus are classified within the order Squamata, suborder Lacertilia (also known as Sauria), family Teiidae, and subfamily Tupinambinae, encompassing large-bodied lizards primarily distributed in the Neotropics.^[13] This placement reflects their position among lacertoidean lizards, distinct from other squamate groups like iguanian or gekkotan lineages. While the term "tegu" most commonly refers to species in Teiidae, it is occasionally applied loosely to certain small-bodied species in the related family Gymnophthalmidae, such as Gymnophthalmus underwoodi, due to superficial similarities in appearance or regional nomenclature.^[14] The evolutionary history of Teiidae traces back to an ancient lineage that originated in the Early Cretaceous, with divergence events estimated around 100 million years ago, coinciding with the breakup of Gondwana and the initial radiation of squamates in the Americas.^[15] Following their dispersal from North America to South America, likely during the Paleogene, Teiidae adapted to diverse Neotropical environments, including forests, savannas, and arid regions, where they underwent significant diversification during the Cenozoic era. This adaptation is marked by convergent evolution with Old World monitor lizards (family Varanidae), particularly in body form—such as elongated snouts, powerful limbs, and robust tails—and foraging behaviors, despite the families being only distantly related within Squamata.^[16] Recent taxonomic revisions have refined the classification of tegus, notably through a 2012 morphological and phylogenetic study that resurrected the genus Salvator from synonymy under Tupinambis, distinguishing it based on shared derived characters like hemipenial morphology and cranial features.^[13] Subsequent molecular analyses between 2012 and 2015 confirmed this split, using mitochondrial and nuclear DNA to resolve paraphyly in the former Tupinambis and support monophyly for both Salvator and the revised Tupinambis, enhancing understanding of tegu diversification in South America.^[17] These updates underscore the integration of morphological and genetic data in clarifying teiid phylogeny.

Genera and species

The primary genera of tegus belong to the family Teiidae and include Salvator and Tupinambis, comprising a total of 11 recognized species across both genera.^[18]^[19] These large-bodied lizards are native to South America, with Salvator species generally exhibiting more robust morphologies and distributions centered in southern regions, while Tupinambis species tend to be more slender and occur predominantly in northern areas, some displaying arboreal adaptations.^[20] The genus Salvator, resurrected in 2012 based on phylogenetic evidence distinguishing southern clades from northern ones, contains three species: S. merianae (Argentine black and white tegu), S. rufescens (red tegu), and S. duseni (yellow tegu).^[21] S. merianae is the most widespread and commonly encountered, known for its striking black-and-white patterning in juveniles that fades with age, while S. rufescens features reddish hues and S. duseni displays yellowish tones, all sharing a sturdy build suited to terrestrial lifestyles.^[22]^[23]^[24] The genus Tupinambis encompasses eight species, including T. teguixin (gold tegu), T. longilineus (Amazon blue tegu), T. cryptus, T. palustris, T. quadrilineatus, T. cuzcoensis, T. zuliensis (Zulia tegu), and T. matipu (Matipu tegu).^[2]^[25] Three of these (T. cryptus, T. cuzcoensis, and T. zuliensis) were described in 2016 from cryptic diversity within the T. teguixin group, highlighting sympatric speciation in northern South American forests; a further species, T. matipu, was described in 2018 from central Brazil. T. teguixin is notable for its golden-striped body, and T. longilineus for blue-gray coloration, with several species showing climbing behaviors.^[2] Smaller lizards informally referred to as "dwarf tegus" occur in secondary genera outside the main large-bodied clades, including Callopistes in Teiidae and Gymnophthalmus in Gymnophthalmidae, totaling around 10 species but with 4-5 key ones exhibiting microteiid traits such as diminutive size (under 20 cm), cylindrical bodies, and specialized scales.^[26] In Callopistes, the two species (C. maculatus and C. flavipunctatus) are terrestrial desert dwellers with spotted or yellow-punctated patterns.^[27] The genus Gymnophthalmus includes species like G. speciosus (golden spectacled tegu) and G. underwoodi, characterized by transparent lower eyelids forming "spectacles" and leaf-litter foraging habits.^[28]^[29] These microteiids differ markedly from larger tegus in scale and ecology but share distant familial ties within Teiidae and related groups.^[30]

Physical description

Morphology

Tegus possess a robust, elongated body plan typical of the Teiidae family, featuring a broad, elongated snout that contributes to their streamlined form. Their limbs are well-developed and sturdy, each terminating in five toes armed with sharp claws suitable for digging burrows and climbing vegetation or structures. The tail is long and muscular, providing essential support for balance during locomotion and serving as a defensive weapon capable of delivering powerful lashes. This overall morphology reflects adaptations for a terrestrial lifestyle involving both foraging on the ground and occasional arboreal or fossorial activities, with a superficial resemblance to monitor lizards resulting from convergent evolution in body proportions and limb structure.^[31] The integument of tegus is covered in distinctive scale patterns that vary regionally. Dorsal scales are small, flat, and oval-shaped, arranged in a juxtaposed manner across the body and tail, contributing to flexibility. In contrast, ventral scales are smooth and beaded, organized into regular transverse rows that facilitate movement over substrates. Along the inner thighs, tegus exhibit femoral pores—specialized openings in pore-bearing scales linked to underlying glands that produce secretions for chemical communication. These pores are more prominent in males and form a continuous row from the precloacal region to the knee.^[32]^[33] Internally, key anatomical features include a bifurcated tongue, which is deeply forked and protrudes from the mouth for sensory exploration. The jaws are powerful and robust, supported by a kinetic skull structure that allows wide gape. Tegus have pleurodont dentition, with teeth anchored along the medial surface of the jawbones; anterior teeth are conical and recurved for grasping, while posterior teeth become blunt and molariform in adults, enabling efficient crushing of hard-shelled prey.^[34]^[31]^[3]

Size and coloration

Tegus exhibit considerable variation in body size among species. Smaller species, such as Salvator duseni, reach total lengths of about 0.8 meters and weights under 2 kilograms in adulthood. Larger Salvator species, like S. rufescens, attain total lengths of 1.2 to 1.4 meters and weights up to 7-10 kilograms.^[35] The largest species, Salvator merianae, can attain a total length of up to 1.6 meters and a weight of 8 kilograms, particularly in mature males, reflecting its robust build.^[36] Tupinambis species are generally slightly smaller; for example, the gold tegu (T. teguixin) reaches up to 1 meter in total length and 4 kilograms in weight.^[37] Females across species are generally smaller than males, though sexual dimorphism is more pronounced in head size than in overall body proportions.^[38] Coloration in tegus typically features a dark base color of black or brown, accented by contrasting bands in white, yellow, or red that run along the body and tail, providing camouflage in their forested habitats.^[39] Juveniles display brighter patterns, often with vivid yellow or white spots and bands that fade as adults develop more subdued, mottled appearances dominated by darker tones.^[39] For instance, S. merianae shows bold black-and-white banding in adults, while S. rufescens incorporates reddish hues in its bands, and S. duseni features yellowish markings; sexual dimorphism in coloration is minimal, with differences primarily limited to intensity rather than pattern.^[21] Growth in tegus is rapid during the juvenile phase, allowing individuals to reach substantial size within the first few years, with sexual maturity typically occurring at 2 to 3 years of age.^[40] In the wild, tegus have a lifespan of 15 to 20 years, though those in captivity can live up to 25 years with appropriate care.^[41]

Physiology

Endothermy

Tegus, particularly the Argentine black and white tegu (Salvator merianae), exhibit a form of partial endothermy that is highly unusual among reptiles, allowing them to generate and maintain elevated body temperatures endogenously during specific life stages. This facultative endothermy enables individuals to raise their core body temperature by 5–10°C above ambient levels, with sustained differences of 5–6°C observed under controlled conditions, primarily during the reproductive season from September to November in the Southern Hemisphere. This elevation is achieved through a combination of increased metabolic rates—doubling or tripling baseline levels—and reduced thermal conductance, which minimizes heat loss to the environment.^[42] The physiological mechanisms underlying this endothermy involve non-shivering thermogenesis driven by enhanced mitochondrial function in skeletal muscle tissue. During the spring reproductive period, mitochondrial density increases, as evidenced by higher citrate synthase activity, and the adenine nucleotide translocase (ANT) protein becomes more abundant and active, facilitating uncoupled respiration that produces heat without muscle contraction. This process is hormonally regulated, with elevated levels of sex steroids like testosterone and estradiol, along with thyroid hormones, triggering the metabolic shift post-hibernation to support gonadal development, mating activity, and, in females, egg production. Unlike mammalian non-shivering thermogenesis, which relies on uncoupling protein 1 (UCP1), tegu endothermy does not activate UCP homologs, highlighting a distinct evolutionary pathway.^[43] This trait is rare among squamate reptiles, where most species rely on ectothermy and behavioral thermoregulation, achieving only minor temperature excesses of 0.5–1.5°C through activity or basking. In S. merianae, endothermy likely evolved as an adaptation to temperate habitats with seasonal hibernation, providing a reproductive advantage by enabling activity in cooler post-winter conditions when ambient temperatures are suboptimal for egg incubation and mate competition. However, this capacity is not universal across tegu species; tropical congeners like the red tegu (Salvator rufescens) lack hibernation and the associated endothermic response, remaining strictly ectothermic.^[42]

Sensory systems

Tegus possess a highly developed olfactory system, primarily facilitated by their forked tongue and the vomeronasal organ, also known as Jacobson's organ. The forked tongue collects chemical particles from the air or substrate through frequent flicking, delivering them to the vomeronasal organ located in the roof of the mouth, where sensory neurons detect pheromones and other scents.^[44] This mechanism enables precise localization of odors via tropotaxis, as each fork of the tongue samples slightly different locations, allowing the brain to compare concentrations and determine direction.^[44] In tegus, such as Salvator merianae, the extremely bifid tongue enhances this capability, supporting functions like prey detection during hunting and territory marking through recognition of conspecific chemical signals.^[44]^[45] Vision in tegus is adapted for diurnal activity, featuring large eyes with round pupils that provide a wide field of view and good resolution in bright light. These lizards exhibit color vision, mediated by cone photoreceptors sensitive to a range of wavelengths, which aids in identifying ripe fruits, foliage, and potential mates.^[46] However, their visual system relies heavily on motion detection for spotting prey, with stationary objects often overlooked despite color discernment.^[47] Studies on Salvator merianae indicate a retinal structure supporting moderate visual acuity, suitable for their active foraging lifestyle in varied habitats.^[48] Beyond olfaction and vision, tegus have acute hearing and tactile sensitivity that complement environmental perception. Hearing occurs through the tympanic membrane, a thin external eardrum that vibrates in response to airborne sounds and ground-borne vibrations, transmitting signals via the middle ear to the inner ear's basilar papilla.^[49] In tegus, auditory sensitivity peaks around 4 kHz, allowing detection of low-frequency vibrations from approaching predators or prey movements in soil.^[50] Tactile senses are provided by mechanoreceptors embedded in their scales, including scale sensilla—small dome-shaped organs that respond to touch, pressure, and subtle vibrations—facilitating navigation through burrows and detection of surface textures during movement.^[51] These sensory modalities integrate with olfaction and vision to support effective foraging, though detailed behavioral applications are explored elsewhere.

Distribution and habitat

Geographic range

Tegus, belonging to the genera Salvator and Tupinambis, are native to regions of Central and South America, primarily east of the Andes, spanning from Panama southward to northern Argentina.^[1] The family Teiidae's largest members, these lizards occupy diverse Neotropical landscapes, with their core distributions concentrated in tropical and subtropical zones.^[1] Species in the genus Salvator, such as S. merianae and S. rufescens, are predominantly found in the southern cone of South America, including southeastern Brazil, Paraguay, eastern Uruguay, and northern and central Argentina.^[8] In contrast, Tupinambis species, including T. teguixin, inhabit northern tropical areas, such as the Amazon Basin, the Guianas (Guyana, Suriname, French Guiana), and extending into Panama.^[52] These distributions reflect adaptations to varying climatic gradients across the continent. Other introduced populations include S. merianae on Fernando de Noronha, Brazil, and T. teguixin on San Andres Island, Colombia.^[1] Introduced populations have become established outside their native range, primarily through releases from the pet trade. In the United States, Salvator merianae (Argentine black and white tegu) has formed breeding populations in Florida since the early 2000s, and Tupinambis teguixin (gold tegu) has an established population in Miami-Dade County; as of 2025, over 10,000 S. merianae have been documented in Florida, with confirmed sites in Miami-Dade, Hillsborough, Charlotte, and St. Lucie counties, and potential spread to additional areas like Lee County.^[8]^[53] Sporadic individuals have been reported in Georgia, where small established groups exist in Toombs and Tattnall counties; as of 2025, reports surged to 11 in southeast Georgia, with new sightings in northern counties including Clarke, Franklin, Hall, and Union.^[54]^[55]^[56] Isolated detections occur in Hawaii, though no breeding populations are confirmed there.^[57] Potential further spread may occur via unintentional transport in shipping containers or additional pet releases.^[58] Biogeographically, Salvator and Tupinambis exhibit largely parapatric distributions, with limited overlap in transitional zones between northern tropical forests and southern subtropical regions, influenced by historical vicariance events in South America.^[1] Their ranges are generally limited to elevations below 2,500 meters, though some populations approach 2,000 meters in Andean foothills.^[1]

Habitat types

Tegus are ecological generalists across both genera, exhibiting broad habitat preferences in diverse ecosystems. Species in the genus Salvator, such as S. merianae and S. rufescens, primarily favor tropical rainforests, savannas, semi-arid scrublands, and flooded grasslands in South America.^[1] These lizards thrive in both undisturbed environments like moist forests and savannahs, as well as drier regions such as the dry Chaco and Monte scrublands.^[1] Species like the black and white tegu (Salvator merianae) commonly inhabit humid pampas and Chaco woodlands, while the red tegu (Salvator rufescens) prefers semi-arid deserts, open fields, and savannas with periodic moisture.^[21] Tupinambis species, such as T. teguixin, occupy similar generalist roles, preferring moist tropical forests, savannas, and disturbed areas in northern regions.^[1] As opportunistic habitat users, tegus frequently exploit human-modified landscapes, including agricultural fields and urban edges, where they find ample foraging opportunities and shelter.^[1] They demonstrate remarkable adaptability to varying conditions, tolerating seasonal flooding in subtropical regions that alternate between wet and arid periods, which allows populations to persist in flood-prone grasslands and swamps.^[21] Certain species, particularly the red tegu, show semi-aquatic tendencies, often residing near rivers or wetlands where they can soak to regulate body temperature and evade predators.^[59] Burrowing serves as a key adaptation, with tegus excavating burrows in loose soil for shelter, thermoregulation, and nesting; they may also repurpose abandoned burrows from armadillos or other animals to minimize energy expenditure.^[1]^[21] In terms of microhabitat utilization, tegus are diurnal foragers that select open areas for basking on sunny substrates to maintain optimal body temperatures, while retreating to nocturnal burrows to avoid nocturnal predators and extreme conditions.^[1] They generally avoid dense understory vegetation, preferring expansive, less obstructed foraging zones in grasslands or forest edges that facilitate their terrestrial locomotion and predatory behaviors.^[60] This selective use of microhabitats underscores their versatility, enabling efficient resource exploitation across heterogeneous landscapes.^[1]

Behavior and ecology

Diet and foraging

Tegus exhibit an omnivorous diet, typically consisting of 50–70% animal matter and 30–50% plant material, reflecting their opportunistic feeding strategy in diverse habitats. Animal components include a variety of invertebrates such as insects (e.g., beetles and orthopterans), small vertebrates like amphibians, reptiles, birds, and rodents, as well as eggs and carrion. Plant matter encompasses fruits, flowers, seeds, and occasionally honey, allowing tegus to exploit seasonal resources effectively. This balanced intake supports their growth and energy needs across life stages.^[61]^[62] Dietary composition varies seasonally, with tegus shifting toward greater consumption of fruits and invertebrates during wet or summer periods when these resources are abundant, while favoring vertebrates in drier or spring conditions. Juveniles are predominantly insectivorous, focusing on invertebrates to meet high protein demands for rapid growth, whereas adults adopt a broader omnivorous profile that incorporates more vertebrates, eggs, and plant material. This ontogenetic shift enables adaptation to changing prey availability and body size constraints.^[62]^[63] Foraging occurs actively during daylight hours, with tegus employing tongue-flicking to sample airborne and substrate scents, facilitating the detection and tracking of prey via their vomeronasal system. As generalist hunters, they dig for buried items, pursue mobile prey, and scavenge opportunistically from nests, carcasses, or human refuse, demonstrating high voracity and the ability to consume items up to their own body size. Their digestive system is complemented by a relatively high metabolic rate that accommodates this varied intake.^[64]^[61]

Daily behavior and activity

Tegus are strictly diurnal lizards, emerging from burrows in the morning to bask and forage, with activity typically spanning 9-15 hours per day depending on environmental conditions. They exhibit bimodal or unimodal activity patterns, peaking shortly after sunrise when they bask to elevate their body temperature to approximately 35-37°C for optimal physiological function. This thermoregulation supports their active exploration and territorial patrols throughout the day.^[65]^[66] Adult males maintain larger home ranges, often exceeding 20 hectares, and actively patrol linear distances of up to 2 kilometers to defend territories, while females occupy smaller ranges typically under 10 hectares centered on suitable microhabitats. These lizards display low aggression toward conspecifics and humans, preferring to flee or emit hisses and threat displays such as arching their bodies when confronted, rather than engaging in physical confrontations.^[67]^[68] In the wild, tegus are predominantly solitary, interacting only briefly with others during mating periods and avoiding prolonged social contact to minimize competition. In captivity, however, individuals can develop familiarity with handlers, recognizing them through consistent positive interactions and exhibiting reduced stress responses over time.^[69]^[70] Southern populations of tegus, such as Salvator merianae, enter a state of estivation or brumation during the austral winter from approximately June to September, retreating to burrows for up to five months in response to cold and dry conditions that limit activity.^[71]

Reproduction

Tegus exhibit a polygynous mating system in which dominant males compete for access to multiple females through aggressive displays and territorial defense.^[20] Breeding typically occurs immediately after the lizards emerge from hibernation in the southern hemisphere spring, from September to November, aligning with peak hormonal activity and mate-searching behaviors.^[72] Tegus are oviparous reptiles, with gravid females excavating humid underground burrows to deposit a single clutch of 17 to 43 eggs, averaging around 29 per clutch depending on maternal body size.^[73] The eggs require incubation temperatures of 28 to 32°C for successful development, with the period lasting 60 to 75 days under natural or controlled conditions.^[74] Sexual maturity is attained at a body mass of 300 to 500 g, corresponding to a snout-vent length of approximately 23 to 27 cm and occurring around 2 years of age.^[73] Parental care is limited, with females showing increased aggression and briefly guarding the nest site after oviposition to deter predators, but providing no further assistance once incubation begins.^[72] Hatchlings are precocial, emerging fully independent and capable of foraging immediately.^[74] During the reproductive phase, females leverage a temporary endothermic boost to maintain elevated body temperatures, aiding egg development.^[72]

Interactions with humans

As pets

Tegus, particularly the Argentine black and white tegu (Salvator merianae) and red tegu (Salvator rufescens), have gained popularity in the exotic pet trade due to their intelligence, trainability, and ability to form bonds with owners, often earning them comparisons to "reptile dogs."^[6]^[75] These species are favored over others for their calm demeanor in captivity and responsiveness to handling, with owners reporting successful training using techniques like clicker conditioning.^[76]^[77] Caring for tegus as pets demands significant resources and long-term commitment, as adults can reach lengths of 4-5 feet and require spacious enclosures to accommodate their active nature.^[76] Minimum enclosure sizes start at 2x4x2 feet for juveniles but must expand to at least 8x4x4 feet for adults to allow for digging, climbing, and exercise; custom-built setups with secure lids are essential to prevent escapes.^[78] Their diet should consist of approximately 60% high-quality protein sources (such as insects, lean meats, and eggs) and 40% vegetables and fruits (including leafy greens like dandelion and items like bell peppers), dusted with calcium supplements and fed 2-3 times weekly for adults.^[79] Proper husbandry includes 12-14 hours of daily UVB lighting to prevent metabolic bone disease, with basking temperatures of 95-110°F and ambient gradients down to 75-85°F, alongside humidity levels maintained at 60-80% through misting and moist substrate.^[80]^[81] With optimal care, tegus can live 20 years or more, though some exceed 30 years, underscoring the need for dedicated owners.^[81] Ownership of tegus is legally permitted in many U.S. states, such as Texas, though restrictions vary and may require permits or microchipping in places like Florida and Georgia for pre-existing pets.^[82] They are banned in Hawaii due to invasive species concerns.^[57] Internationally, both Salvator merianae and Salvator rufescens are listed under CITES Appendix II, regulating trade to prevent overexploitation while allowing commerce with proper permits.^[83]

Hunting and trade

Tegus, particularly species in the genera Salvator and Tupinambis, have been traditionally hunted in rural South America for their meat, which serves as a high-protein, low-fat source of bushmeat in nutrient-deficient communities. In regions like eastern Argentina, Paraguay, and Brazil, tegu meat is consumed by local households and used to supplement diets, often prepared as stews or grilled dishes that provide essential nutrition where access to other proteins is limited.^[84]^[85] The fat extracted from tegus is widely valued in traditional medicine, applied topically to treat conditions such as rheumatism, inflammation, and joint pain due to its perceived anti-inflammatory properties.^[86] Hides are utilized for crafting leather goods, including bags and belts, in local artisanal practices that date back generations.^[84] Commercial exploitation of tegus focuses primarily on their skins for the international leather trade, with significant harvests occurring in Argentina, Paraguay, and Brazil. In Argentina, tegus (Salvator merianae and Salvator rufescens) have been commercially harvested for over 50 years, resulting in the export of approximately 31 million skins between 1941 and 1998, though global trade volumes have since declined by more than 90% from their 1980s peak of 1.9 million skins annually.^[84] Paraguay maintains an annual export quota of 300,000 skins, occasionally exceeded during periods of high demand, while Brazil contributes to regional bushmeat and skin markets without specified quotas.^[38] Juveniles are exported for the pet trade, and meat serves as a byproduct in some operations, with all species listed under CITES Appendix II since 1977 to regulate international commerce.^[84] Skins are processed into small luxury items like watch straps and boots, supporting tanneries in countries such as Argentina and Paraguay.^[84] This trade provides vital economic support to rural and indigenous communities in South America, where hunters earn supplemental income—often less than US$5 per day—during agricultural off-seasons or economic hardships, such as the 2002 crisis in Argentina or the COVID-19 pandemic.^[84] In Paraguay, the harvest sustains local livelihoods through sales to middlemen and exporters, while in Argentina, the Tupinambis Commission enforces size restrictions and quotas to promote sustainability, targeting mature individuals to minimize impacts on populations.^[84]^[38] Despite these measures, intensive harvesting in some areas has led to localized population declines, though overall resilience from large clutch sizes and broad habitats allows for managed quotas in regulated regions.^[84]

Invasive species

The Argentine black and white tegu (Salvator merianae) and gold tegu (Tupinambis teguixin) have established invasive populations in the southeastern United States, primarily in Florida, where breeding groups are confirmed in Miami-Dade, Charlotte, Hillsborough, and St. Lucie counties, with sightings extending northward to Polk County and beyond.^[87] By 2025, over 10,000 individuals have been documented statewide through removals and reports, reflecting rapid expansion from initial introductions.^[53] Smaller established populations exist in southeast Georgia's Toombs and Tattnall counties, where eradication efforts have removed dozens of individuals since 2018.^[39] These invasions trace back to escapes and releases from the pet trade, with a key surge following Hurricane Andrew in 1992, which damaged reptile facilities and homes in South Florida, allowing early releases into the wild.^[88] Ecological impacts are significant, as tegus prey on eggs and juveniles of native species, including ground-nesting birds, sea turtles, and American alligators, potentially threatening imperiled populations in sensitive habitats like the Everglades.^[89] They also compete with native wildlife for food and burrow extensively, damaging agricultural crops such as fruits and vegetables while undermining structures and levees in urban and natural areas.^[87] Rapid reproduction exacerbates the spread, with females maturing in as little as 24 months and laying clutches of 11–32 eggs annually, enabling quick population growth in Florida's subtropical climate.^[58] Management responses include Florida's 2021 ban on tegu possession, sale, and breeding, enforced by the Fish and Wildlife Conservation Commission (FWC), which prohibits commercial activities and allows humane removal on private lands.^[8] Interagency programs involving FWC, University of Florida, U.S. Geological Survey, and National Park Service conduct trapping, telemetry tracking, and public reporting to remove individuals and contain spread, with over 400 captured annually in targeted efforts.^[87] Early detection protocols are active in Texas and California, where isolated sightings prompt rapid response to prevent establishment, supported by national invasive species databases.^[90]

Conservation status

The genus Salvator, comprising the tegu lizards, includes three recognized species: S. merianae (Argentine black-and-white tegu), S. rufescens (red tegu), and S. duseni (yellow tegu). All are classified as Least Concern on the IUCN Red List as of 2025, reflecting their wide distributions across South America and presumed stable populations despite localized pressures.^[91]^[92]^[93] No species is listed as Endangered or Critically Endangered, though S. rufescens has experienced documented population declines in specific regions like the Argentine Chaco, prompting calls for monitoring.^[94] Wild tegu populations face primary threats from habitat degradation, particularly deforestation in the Amazon Basin and Gran Chaco regions, which fragments suitable forested and savanna habitats essential for foraging and burrowing. Overharvesting for meat and skins remains a concern in countries like Argentina, Bolivia, and Paraguay, where tegus are commercially exploited, potentially exacerbating local declines when combined with habitat loss.^[95] Roadkill from expanding road networks also contributes to mortality, especially during seasonal migrations and post-hibernation activity periods.^[94] Emerging pressures from climate change may disrupt hibernation cycles by altering seasonal temperature cues in subtropical ranges, though tegus demonstrate physiological adaptability to varying conditions.^[96] Conservation measures include protection within national parks, such as Iguazú National Park in Argentina, where S. merianae populations benefit from habitat safeguards and reduced poaching. In Bolivia's Chaco region, community-based programs promote sustainable harvesting through hunter self-monitoring and quotas, helping maintain viable populations while supporting local livelihoods.^[97] Ongoing research into population genetics informs management by revealing connectivity between subpopulations, aiding efforts to mitigate fragmentation effects in fragmented landscapes.^[20] All species are regulated under CITES Appendix II to control international trade and prevent overexploitation.

References

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Modeling the distributions of tegu lizards in native and potential ...
Jul 5, 2018 · Tegu lizards are widely distributed in South America east of the Andes, and are popular in the international live animal trade. Two species are ...
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Cryptic, Sympatric Diversity in Tegu Lizards of the Tupinambis teguixin Group (Squamata, Sauria, Teiidae) and the Description of Three New Species
### Tegu Lizards: Encyclopedia Introduction Summary
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[PDF] FWC BIOPROFILE FOR THE ARGENTINE BLACK AND WHITE ...
Tegus are the largest terrestrial lizards in the New World, and T. merianae and T. rufescens are the largest tegu species, reaching up to 145 cm (57 in) total ...
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Salvator & Tupinambis Tegu Species - ReptiFiles
Colombian and Argentine tegus are a collection of species classified under the genera Tupinambis and Salvator. Learn more about all 7 tegu species here.
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[PDF] The Relationship between People and the Tegu
May 3, 2022 · Formerly classified in the genus Tupinambis, these lizards were reclassified in the genus Salvator when the Teiidae family was restructured in ...
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Aug 7, 2024 · Salvator merianae, a giant tegu lizard endemic to South America, regulates its own body temperature during the mating season without relying on external heat ...Missing: review - - | Show results with:review - -
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TEJU Definition & Meaning - Merriam-Webster
The meaning of TEJU is any of several large blackish South American lizards ... Word History. Etymology. Portuguese tejú, teiú, from Tupi & Guarani tejú, teyú ...
[9]
Tupinambis teguixin (LINNAEUS, 1758) - The Reptile Database
Apparently, it's the common name for that lizard (tegu or teju is the Tupi term for lizard). ... Catalogue of the lizards in the British Museum (Natural History).
[10]
On 'lost' indigenous etymological origins with the specific ... - ZooKeys
Apr 5, 2018 · The South American tegu lizard Tupinambis teguixin Linnaeus, 1758 is a direct cognate from the extinct language Tupí. The language was ...
[11]
Tegus (Teiidae) | U.S. Fish & Wildlife Service
Working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats. ... Scientific Name. Teiidae. Common Name. Tegus. Ground Lizards.
[12]
Review of Teiid Morphology with a Revised Taxonomy and ... - Biotaxa
Sep 7, 2012 · We propose a new taxonomy of theTeiidae based on recovered evolutionary history and numerous morphological characters surveyed in this study.
[13]
Underwood's Spectacled Tegu (Gymnophthalmus underwoodi)
Gymnophthalmus underwoodi, called commonly Underwood's spectacled tegu, is a species of microteiid lizard, which is found in South America and on certain ...
[14]
(PDF) New taxa of transversely-toothed lizards (Squamata
Aug 6, 2025 · It appears that Teiioidea and Borioteiioidea diverged from a common ancestor by the Early Cretaceous. The Teiioidea entered South America and ...
[15]
A tegu-like lizard (Teiidae, Tupinambinae) from the Middle Miocene ...
Apr 17, 2025 · Tupinambines, commonly referred to as tegus, are a group of large-bodied lizards that evolved and diversified in South America, where they have ...
[16]
Molecular systematics of teioid lizards (Teioidea ...
Mar 17, 2016 · The relationships of Tupinambinae are better resolved, and Tupinambis is recovered as monophyletic, while Salvator is paraphyletic with respect ...
[17]
https://onlinelibrary.wiley.com/doi/10.1111/cla.12150
[18]
Population genetics of Salvator merianae (Reptilia, Teiidae) in its ...
We analyzed their genetic diversity, structure, and mating system in Argentina using the mitochondrial ND4 locus and 10 microsatellite loci.
[19]
Salvator Tegu Care Information - Reptiles Magazine
### Summary of Salvator Tegu Anatomical Features
[20]
Salvator merianae - The Reptile Database
Molecular phylogenetics and conservation of Tupinambis (Sauria: Teiidae). ... Review of Teiid Morphology with a Revised Taxonomy and Phylogeny of the Teiidae ( ...
[21]
https://reptilesmagazine.com/salvator-tegu-care-information/
[22]
https://reptile-database.reptarium.cz/Salvator/merianae
[23]
Cryptic, Sympatric Diversity in Tegu Lizards of the Tupinambis ...
Abstract. Tegus of the genera Tupinambis and Salvator are the largest Neotropical lizards and the most exploited clade of Neotropical reptiles.
[24]
https://reptile-database.reptarium.cz/Salvator/duseni
[25]
https://meridian.allenpress.com/herpetologica/article/74/1/65/14420/A-New-Species-of-Tupinambis-Teiidae-from-Central
[26]
[PDF] New records of the Golden Spectacled Tegu, Gymnophthalmus ...
Sep 21, 2025 · The Golden Spectacled Tegu (Gymnophthalmus speciosus) is a small lizard characterised by four toes on the forelimbs, a body covered with large ...Missing: dwarf Callopistes
[27]
https://reptile-database.reptarium.cz/Callopistes/flavipunctatus
[28]
Systematics of Neotropical microteiid lizards (Gymnophthalmidae ...
Jul 16, 2018 · At the moment, Cercosaurinae consists of 15 formally described genera: Anadia, Andinosaura, Cercosaura, Echinosaura, Euspondylus, Gelanesaurus, ...
[29]
(PDF) Review of Teiid Morphology with a Revised Taxonomy and ...
Sep 7, 2012 · We propose a new taxonomy of the Teiidae based on recovered evolutionary history and numerous morphological characters surveyed in this study.
[30]
A Review of the Tegus, Lizard Genus Tupinambis (Sauria - jstor
Dorsal scales small, flat, oval, juxtaposed. Ventral scales smooth, regular, in 19-38 longitudinal rows. Cushion scales well developed; finger la- mellae ...
[31]
(PDF) Functional Morphology of Femoral Glands in the Tegu Lizard ...
Aug 6, 2025 · In this paper we describe the morphological organization of the femoral glands in the Tegu, Tupinambis merianae, by means of light and electron ...Missing: dorsal | Show results with:dorsal
[32]
[PDF] Functional morphology of the tongue of lizard Salvator merianae ...
Light microscopy images of Salvator merianae tongue. A) Apex of the tongue with stratified squamous epithelium and two keratin bands (k). Blue toluidine ...
[33]
[PDF] tegu (Salvator merianae) of Fernando de Noronha - SPREP Library
The black and white tegu (Salvator merianae) ... 1), hereby referred to as tegu, is the largest lizard in South America, up to 160 cm in total length and weighting ...
[34]
[PDF] Monitoring and Managing the Harvest of Tegu Lizards in Paraguay
—The monitoring data reflected known differences between the species and patterns of sexual size dimorphism. Red tegus were larger on average. (F: x¯ SVLest ...
[35]
Argentine Black and White Tegus | Department Of Natural ...
Growing up to 4 feet long and weighing 10 pounds or more, this lizard native to South America is an invasive species that threatens Georgia wildlife.Missing: review - - | Show results with:review - -
[36]
https://library.sprep.org/sites/default/files/2021-04/population-assessment-novel-island-invasive.pdf
[37]
[PDF] Red Tegu - Reptile Adventure Camp
A healthy tegu can live for 15 to 20 years in the wild, and even longer in captivity. ... Unlike some other lizard species, they are not arboreal as adults, but ...
[38]
Seasonal reproductive endothermy in tegu lizards | Science Advances
Jan 22, 2016 · Increased metabolic rates and decreased thermal conductance are the same mechanisms involved in body temperature regulation in those ...
[39]
Mitochondrial function in skeletal muscle contributes to reproductive ...
May 13, 2024 · Mitochondrial function in skeletal muscle contributes to reproductive endothermy in tegu lizards (Salvator merianae). Livia Saccani Hervas ...Abstract · INTRODUCTION · DISCUSSION · MATERIALS AND METHODS
[40]
Evolutionary morphology of the lizard chemosensory system - PMC
Sep 4, 2017 · Squamate 'vomerolfaction' is mediated by 'tongue-flicking' behaviour in which the tongue samples substrate-bound or air-born chemicals in the ...Missing: squamata | Show results with:squamata
[41]
Cold-blooded cognition: Recent advances in reptile cognition and ...
Both male and female Argentine black and white tegu lizards (Salvator merianae) are able to track conspecific scent trails through the detection of skin lipids ...
[42]
Reptile Vision - Anapsid.org
Some nocturnal lizards have slit pupils, others are round. Lizards, unlike other reptiles, have a choroid body, called the conus papillaris. Projecting out into ...
[43]
The Diversity and Adaptive Evolution of Visual Photopigments in ...
This review will discuss what is currently known about the evolution of opsin-based photopigments in reptiles, relating habitat to photoreceptor morphology.
[44]
[PDF] CVM Intramural
Retinal ganglion cells are the bottleneck to central vision, meaning they are a great proxy for visual acuity. ... black and white tegu (Salvator merianae).
[45]
Hearing, Adaptations, Ears - Reptile - Britannica
Oct 27, 2025 · The reptilian auditory apparatus is typically made up of a tympanum, a thin membrane located at the rear of the head; the stapes, a small bone ...Missing: tegu | Show results with:tegu
[46]
[PDF] Auditory Brainstem Responses and Otoacoustic Emissions in Lizards
As in the audiograms we saw that the temperature effects appeared more pronounced in species with a continuous overlying tectorial membrane (Whiptail, Tegu) ...
[47]
The evolution of scale sensilla in the transition from land to sea in ...
Jun 1, 2016 · Scale sensilla are small tactile mechanosensory organs located on the head scales of many squamate reptiles (lizards and snakes).
[48]
Argentine Black and White Tegu - FWC
Tegus (all species within genera Salvator and Tupinambis) were added to Florida's Prohibited species list. Learn how this impacts pet owners and other ...Missing: Teiidae | Show results with:Teiidae
[49]
Evidence for an established population of tegu lizards Salvator ...
Nov 4, 2020 · To evaluate the probability of establishment, we assembled verified records of the non-native Argentine Giant Tegu in Georgia over the past nine ...Missing: Hawaii shipping
[50]
Illegal Tegu Lizard Found in Waianae - Hawaii.gov
Feb 22, 2011 · The foot-and-a-half long lizard has been identified as a tegu lizard (Tupinambis teguixin), which are illegal in Hawaii.
[51]
Modeling current and future distribution of invasive tegu lizards ...
There are three species of tegu lizards native to South America and available in the pet trade that have a high risk of invasion and deleterious impacts to ...
[52]
Argentine Red Tegu Lizard - Facts, Habitat, Diet, Pictures, and More
Apr 24, 2019 · Scientific Classification ; Class: Reptilia ; Order: Squamata ; Family: Teiidae ; Genus: Salvator ; Scientific Name: Salvator rufescens ...
[53]
Argentine Tegu | Burpee Museum of Natural History
Quick Facts: Common Name: Argentine Black and White Tegu Scientific Name: Salvator merianae ... Tegus belong to the Teiidae family, representing one of the most ...
[54]
[PDF] Diet of Salvator merianae (Squamata: Teiidae): New prey item and ...
The diet and foraging behavior of this species indicate a possible advantage of the Tegu to adapt to different environmental conditions, and hence, to a ...<|control11|><|separator|>
[55]
[PDF] spatial ecology and diet of the argentine black and white tegu
I compiled triangulated positions for each tegu and combined them with known exact locations. (e.g. tegus in winter burrows) to produce a list of GPS ...
[56]
(PDF) Diet of juvenile tegu lizard Tupinambis merianae (Teiidae) in ...
Feb 6, 2016 · PDF | On Jan 1, 2002, M.C. Kiefer and others published Diet of juvenile tegu lizard Tupinambis merianae (Teiidae) in southeastern Brazil ...
[57]
Strike-induced chemosensory searching by a teiid lizard, the golden ...
Because only active foragers move through the habitat while tongue-flicking and exhibit lingually mediated prey chemical discrimination, only active foragers ...
[58]
Activity pattern of the Black-and-White Tegu, Salvator merianae ...
Feb 5, 2020 · Activity patterns were diurnal and bimodal, and animals were active for 14-15 hours each day. Activity peaked in the morning soon after ...
[59]
Giant tegu lizard is warm-blooded, researchers discover
After daybreak, two hours of basking in the sun raised their average internal temperature to 35-37°C. In late afternoon, the temperature started to fall again, ...Missing: 30-35° | Show results with:30-35°
[60]
Population ecology of Tupinambis merianae (Squamata, Teiidae)
Aug 7, 2025 · Females have small home ranges, centred on nesting sites (Manes et al., 2003), and while males have larger home ranges, they are territorial and ...
[61]
[PDF] an incipient population of argentine black and white tegus (salvator ...
May 4, 2021 · In their native range, Argentine Black and White Tegus (Salvator merianae, previously Tupinambis merianae) are considered habitat generalists ...
[62]
(PDF) Aggressive Behavior and Performance in the Tegu Lizard ...
Aug 6, 2025 · Our results show that independent of their sex, larger individuals with higher bite forces were indeed more aggressive. Moreover, our data show ...
[63]
Argentine Black and White Tegu | Zoology
The Argentine black and white tegu is a large, stocky lizard native to South America and is the largest of the “tegu” lizards. Adults have bold black and ...
[64]
Tegu Handling Tips | ReptiFiles' Tegu Care Guide
Mating season for tegus begins after brumation, which is around March-April in the United States. Male tegus may be sensitive to and exhibit courting behavior ...
[65]
The consequences of seasonal fasting during the dormancy of tegu ...
Apr 19, 2018 · Tegu lizards (Salvator merianae) aestivate for up to 5 months during Brazil's winter, when they retreat to burrows and halt most activities.
[66]
Subtropical hibernation in juvenile tegu lizards (Salvator merianae)
Jun 19, 2018 · This tropical/subtropical reptile enter a state of dormancy, with an 80% reduction in metabolic rate, that remains almost constant during winter.Missing: resurrection | Show results with:resurrection
[67]
Seasonal reproductive endothermy in tegu lizards - PMC - NIH
Jan 22, 2016 · Ectothermic lizards become endothermic in the breeding season, supporting a parental care model for the origins of endothermy.
[68]
None
### Reproduction of Salvator merianae (Argentine Giant Tegu)
[69]
Ultrastructure of eggshell and embryological development of ...
Oct 25, 2020 · The objective of this study was to characterize the external morphology of Salvator meriane embryos in different stages of embryonic development.
[70]
Effects of constant and fluctuating incubation temperatures on ...
Oct 28, 2025 · Incubation time (days) and hatching success (%) of Salvator merianae embryos incubated under three thermal treatments: low constant (29 °C), ...
[71]
Colombian & Argentine Tegu Care Guide - ReptiFiles
Jan 4, 2018 · The lizards we recognize as tegus were classified under the same genus (Tupinambis) until 2012, when three of the species were reclassified ...
[72]
Tegu Care - Chicago Exotics Animal Hospital
Most tegus reach a size of 4-5 feet from snout to tail tip and live around 10-15 years (some have reached 20!) with maturity around 3 years old. Natural History<|separator|>
[73]
https://crocdoc.ifas.ufl.edu/publications/articles/Meshaka%20et%20al.%202019%20Tegu%20ecology.pdf
[74]
Tegu Enclosure Size Guidelines | ReptiFiles' Tegu Care Guide
10'L x 5'W x 5'H / 3 x 1.5 x 1.5m · Females — 8'L x 4'W x 4'H / 2.4 x 1.2 x 1.2m.
[75]
Tegu Food Options | ReptiFiles' Tegu Care Guide
Argentine tegus are omnivores (60% protein, 30% vegetables, 10% fruit) · Colombian tegus are carnivores (90% protein, 10% vegetables).
[76]
Tegu Humidity, Lighting & Heating Requirements - ReptiFiles
125-135°F (52-57°C) ; Warm side — 90-95°F (32-35°C) ; Cool side — 75-85°F (24-29°C).Missing: 30-35° | Show results with:30-35°
[77]
https://reptilinks.com/blogs/news/how-smart-are-tegus-understanding-tegu-intelligence
[78]
Reptile Ownership Laws by State - USARK
Reptile ownership laws vary by state. Some states allow native reptiles, while others restrict certain species or require permits. Local laws may be more ...
[79]
[PDF] Harvest and trade of tegu lizards in Argentina - CITES
The Black and White Tegu (Salvator merianae) and the Red Tegu (Salvator rufescens) are harvested in Argentina for their skins, meat, medicinal value, and to a ...Missing: coloration | Show results with:coloration<|control11|><|separator|>
[80]
CITES and Livelihoods
Case studies on CITES and livelihoods have been collected from countries in Africa, Asia, Europe, Oceania, North America and South America.
[81]
What is the role and contribution of meat from wildlife in providing ...
Oct 1, 2012 · Tegus are large South American lizards that have traditionally been utilized by aboriginal people as a source of protein, fat, and leather.
[82]
Uses of wild vertebrates in traditional medicine by farmers ... - SciELO
The fat of T. merianae is used to treat rheumatism, inflammations, fissures on sole of the feet, and ear-aches (Ferreira et al. 2009) ...
[83]
Growth and Spread of the Argentine Black and White Tegu ...
Sep 23, 2021 · The Argentine black and white tegu (tegu) is one of the largest lizard species in the Western Hemisphere, growing up to four feet in total ...
[84]
Argentine tegu established in Charlotte, may move into Lee, Southeast
Jul 17, 2025 · Argentine black and white tegus, invasive lizards reaching 5 feet long, are spreading across Southwest Florida. Over 10,000 tegus have been ...
[85]
Tegu Lizards Are Taking Over the Everglades - Miami New Times
Nov 1, 2016 · ... Hurricane Andrew. Florida Fish and Wildlife Conservation Commission Officer Pat Reynolds was on the wildlife beat in 1992 when the Category ...
[86]
Florida's tegu lizard invasion updated in a new fact sheet | WUSF
Dec 8, 2021 · Tegus have been reported in 35 Florida counties, including nearly every part of the greater Tampa Bay region. A new factsheet shows their ...
[87]
Early detection and rapid response tools for invasive tegu lizards
Jul 2, 2025 · Tegu sightings in Florida began in 2006, and since then, populations have established in at least two Florida counties and one county in Georgia ...
[88]
https://www.miaminewtimes.com/uncategorized/tegu-lizards-are-taking-over-the-everglades-8890823/
[89]
https://www.wusf.org/environment/2021-12-08/florida-tegu-lizards-migrating-north-what-invasion-means-for-state-wildlife
[90]
https://www.usgs.gov/centers/fort-collins-science-center/science/early-detection-and-rapid-response-tools-invasive-tegu
[91]
(PDF) Decline in the Population of the Red Tegu, Salvator rufescens ...
Jun 27, 2019 · Indirect consequences of habitat loss are lower reproduction success, higher predation rates and the loss of individuals through road kill.
[92]
Tupinambis merianae (black and white tegu) | CABI Compendium
Nov 21, 2019 · This datasheet on Tupinambis merianae covers Identity, Distribution, Biology & Ecology, Further Information.<|separator|>
[93]
Monitoring and Managing the Harvest of Tegu Lizards in Paraguay
Aug 6, 2025 · Ethnozoological notes: Species from the genus Tupinambis are most likely the most hunted lizards in South America, especially for meat and ...