Genus Urostrophus – Steppe Iguanas

Scientific Name

Common Name

Distribution

Size

Notes

Urostrophus

U. chungarae

Bolivia

Described in 2023: see Reptile Database entry.

U. gallardoi

Diving Lizard, Mophead

Bolivia, Argentina

??

An arboreal inhabitant of the eastern Amazon Basin, most often associated with creekside and swamp habitat. [Bartlett and Bartlett]. Like Iguana iguana and certain other lizards of the iguanid and agamid families it is both a good swimmer and good diver [ibid]. Scalation details: canthus rostralis and superciliary edge angular, projecting; nostril pierced above canthus rostralis, nearer end of snout than orbit; upper head-scales small, irregular, strongly keeled or tubercular; enlarged subconical tubercles surrounding large rugose occipital; 5-6 supralabials and 5-6 sublabials; gular scales strongly keeled; throat with strong transverse folds; gulars strongly keeled; nuchal and dorsal crests form low serrated ridge, of which nuchal slightly more developed; dorsal and lateral scales small, equal, rhomboidal, imbricate, strongly keeled; ventrals larger, also strongly keeled; equal keeled scales on limbs. Other: head moderately large, short, rounded; tympanum vertically oval, a little larger than eye-opening; limbs long; digits long and slender, toes strongly denticulated laterally. Tail: strongly compressed, crested like the back; length twice SVL; caudal scales subequal, keeled, the lower larger. Coloration: overall dark; dorsum olive-brown to brown, broken by very small and irregularly arranged flecks; venter and throat light. Reproduction: clutch of 4-10 eggs; incubation about 100 days. [SOURCES: Bartlett & Bartlett, Boulenger]

U. grilli

Boulenger's Tree Lizard

Brazil, Uruguay, Argentina

Former Anisolepis species. Description: head scales small to moderate, smooth, swollen, variable in size. Rostral subpentagonal, 2-3 times as wide as high. 6-7 postrostrals. Nasal ovoid, nostril slightly posterior in position, in contact with the 1^st supralabial or separated from it by 1 scale, separated from the rostral by 1 postrostral. 6-7 scales between the nasals dorsally..... [SOURCE: Etheridge & Williams]

U. longicauda

Long-Tailed Tree Lizard

Brazil, Paraguay, Argentina

TL (m) approx 35 cm, (f) 32 cm; SVL (m) approx 8 cm, (f) 8 cm

Former Anisolepis species. Description: head rather small, body elongate. Nostril lateral, near the end of the snout; ear-opening small, suboval, oblique. Upper head-scales rather small and smooth, smallest on the supraocular region, largest on the snout; occipital slightly enlarged, larger than the ear-opening; 8-9 supralabials, very low. Anterior gular scales small, equal, granular, keeled. Dorsal scales mostly hexagonal, strongly keeled, forming about 12 longitudinal series, passing gradually into the small granules which cover the sides. Ventral scales much larger than dorsals, strongly keeled, shortly mucronate, imbricate, in 16-18 longitudinal series; the keels forming straight longitudinal lines. The adpressed hind limb reaches the shoulder, or halfway between the fore limb and the ear. Tail at least three times as long as head and body, covered with uniform, imbricate, keeled scales. Coloration: pale brown above, with a broader dark dorsal stripe, which may be edged on each side by a blackish line; a blackish streak on the canthus rostralis, and a brown black-edged streak from the eye to the neck, passing through the tympanum; upper lip and lower parts cream-coloured. [SOURCE: Boulenger 1891]

U. undulatus

Wiegmann's Tree Lizard

S Brazil, Uruguay, Argentina

TL 24.5 cm, SVL approx 7 cm

Former Anisolepis species. Description: head small, body elongate. Nostril lateral, near the end of the snout; ear-opening moderately large, oval. Upper head-scales small and smooth, smallest on the supraocular region; occipital enlarged, suboval, about as large as the tympanum; upper labials eight, very low. Gular scales granular and keeled medially, larger and smooth anteriorly, gradually larger, rhomboidal, imbricate, and strongly keeled towards the gular fold, which is strong and straight. Median dorsal scales larger, irregular, imbricate, strongly keeled, the largest forming one or two indistinct longitudinal series on each side of the vertebral line; dorso-lateral scales very small, granular, keeled, unequal, intermixed with irregularly scattered enlarged scales. Ventral scales much larger than dorsals, equal, rhomboidal, imbricate, strongly keeled, the keels forming straight longitudinal series. The adpressed hind limb reaches the axilla or the shoulder. Tail: more than twice as long as head and body, covered with equal keeled scales. Coloration: olive-brown above, with a series of triangular dark brown spots on each side of the vertebral line, forming a zigzag band; this is bordered externally with yellowish or reddish; the triangular spots may send forth narrow dark brown lines obliquely directed posteriorly down the sides; lower surfaces yellowish or coppery, the throat with a few blackish dots or longitudinal lines; tail above with a series of rhomboidal, dark, light-edged spots. [SOURCE: Boulenger 1885]

U. vautieri

Brazilian Steppe Iguana

Brazil

Description: head moderately large; snout rounded, with obtuse canthus rostralis; nostril nearer the end of the snout than the orbit; tympanum oval, as large as the eye-opening; upper head-scales smooth, largest on the snout, smaller on supraorbital region; scales forming regular supraorbital semicircles, separated by 1-2 rows of scales; occipital enlarged, a little smaller than the tympanum; a series of enlarged infraorbitals, second largest; 8-9 upper and 7-8 lower labials. Gular scales small and granular, strongly enlarged and polygonal near the labials. Scales on upper surface of body and limbs very small, granular, juxtaposed, of lower surfaces larger, flat, slightly imbricate, all smooth. Limbs and digits moderately elongate; the adpressed hind limb reaches the shoulder or the neck in males, not to the axilla in females. Tail: about once and a half the length of head and body, curling at the end, covered with small, keeled scales. Coloration: brown above, marbled with darker, dirty white inferiorly; tail above with equidistant black spots. [SOURCE: Boulenger]