Tretioscincus agilis (RUTHVEN, 1916)
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Tretioscincus agilis
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| Higher Taxa | Gymnophthalmidae (Gymnophthalminae), Gymnophthalmini, Sauria, Gymnophthalmoidea, Squamata (lizards) |
| Subspecies | |
| Common Names | E: Smooth Tegu Portuguese: Calango, Calango-do-Rabo-Azul, Lagartinho-de-Rabo-Azul, Lagartixa |
| Synonym | Calliscincopus agilis RUTHVEN 1916: 2 Tretioscincus romani ANDERSSON 1918: 5 Tretioscincus brasiliensis MÜLLER 1923: 55 Calliscincopus romani — AMARAL 1937a: 1739 Calliscincopus agilis — DONOSO-BARROS 1968 Tretioscincus agilis — VANZOLINI & REBOUCAS-SPIEKER 1969: 124 (part) Tretioscincus agilis — PETERS et al. 1970: 262 Tretioscincus agilis— DO NASCIMENTO et al. 1987 Tretioscincus agilis — CASTOE et al. 2004 |
| Distribution | Guyana, Suriname, French Guiana, Brazil (Amazonas, Para), Venezuela Colombia [Castro,F. (pers. comm.)] Type locality: Sand ridges on Demerara River near Dunoon, Guyana. |
| Reproduction | oviparous |
| Types | Holotype: UMMZ 47798 Holotype: NRM [Tretioscincus romani] |
| Diagnosis | Diagnosis. Tretioscincus with prefrontals widely separated, loreal hexagonal, narrowest ventrally, gulars i n five longitudinal rows. Dorsals 25-28 i n a middorsal row, ventrals 15-19 in a midventral row. All dorsals smooth. Scales on tail rounded, in 10 longitudinal rows, mostly smooth; only distal scales on ventral surface keeled. Dorsolateral stripe running on edge of second and third rows of dorsals when counted from midline. In live animals, dorsolateral stripe anteriorly salmon to pale orange, posteriorly yellowish or greenish, and blue on tail (Avila-Pires 1995). Description. Gymnophthalmid with maximum SVL in males of 59 m m , i n females of 62 m m (Hoogmoed, 1973). Head 0.19-0.24 (n= 24) times SVL, relatively larger i n smaller specimens; 1.3-1.6 (1.40 ± 0.06, n= 24) times as long as wide; 1.1-1.5 (1.30 ± 0.08, n= 24) times as wide as high. Snout wide, rounded, rising slightly toward top of head. Neck about as wide as head and anterior part of body. Body cylindrical. Limbs well developed, forelimbs 0.30-0.36 (0.33 ± 0.02, n= 21) times SVL, hind limbs 0.43-0.51 (0.47 ± 0.02, n= 21) times. Inner finger reduced, clawless. Tail round in cross section, tapering toward tip; 1.4-1.6 (n= 8) times SVL, relatively shorter in smaller specimens. Tongue lanceolate, covered with imbricate, scale-like papillae, with a smooth, bifid tip. Anterior teeth conical, posterior teeth bicuspid and tricuspid. Rostral hexagonal, two to three times as wide as long, well visible from above, in wide contact with frontonasal. Frontonasal single, irregularly hexagonal or octagonal, i n contact with rostral, nasal, loreal, prefrontals, occasionally first supraocular, and frontal. Prefrontals small, distinctly separated from each other in all specimens observed, touching frontal or separated from it b y a contact between first supraocular and frontonasal (in six out of 24 specimens examined, both prefrontals are separated from frontal, and in five specimens only one prefrontal is in contact with frontal). Frontal longer than wide, widest anteriorly, either irregularly pentagonal or heptagonal, or more commonly with a curved line forming contact with first supraocular and frontoparietals (approximately bell-shaped, opening pointing anteriorly). Frontoparietals irregularly pentagonal or hexagonal, longer than wide, forming a relatively wide medial suture; each in contact with frontal, first and second supraoculars, one parietal, and interparietal; usually there is a distinct suture with first supraocular, but in MPEG 14911 these scales only touch. Interparietal occasionally irregularly hexagonal, usually roughly rhomboid, with anterior sides short and straight, posterior sides longer, rounded. One parietal at each side of interparietal, wider and shorter than it. Two supraoculars, first largest and frequently extending beyond second toward middorsal line. Three, rarely two, supraciliaries, first highest, second shortest. Nasal undivided, nostril approximately halfway its length, close to suture with supralabials. Loreal relatively large, hexagonal, contact with supralabials shorter than that with frontonasal and prefrontal (which is angulate). Frenocular small (in RMNH 25444 there are two frenoculars, one behind the other), continuous with a subocular series of three to five (mostly five) scales, among which a higher preocular and a much higher postsubocular. Postsubocular in contact with posterior supralabial, and separated from parietal by one, occasionally two, scale(s) which, together with another scale posterior to supraocular and supraciliary series, can be considered as postoculars. Lower eyelid with undivided, semitransparent disc. Pupil round with long and narrow ventral and dorsal flaps projecting inwards. Five or, mostly, six supralabials, one before last below centre of eye; followed by two postsupralabials, about as high as posterior supralabial or slightly tapering posteriad. Temporal region with a few subhexagonal, smooth, imbricate scales, in some specimens wider posteriorly. Ear-opening relatively small, with smooth margins; tympanum deeply recessed within an auditory meatus. Mental trapezoidal, convex anteriorly. Postmental undivided, irregularly pentagonal or heptagonal. Three pairs of chinshields, all in contact with infralabials and medially (in RMNH 25442 and RMNH 25444 third pair separated medially). Four infralabials, suture between third and fourth, or beginning of fourth infralabial below centre of eye; followed by two or three postinfralabials, in some specimens first postinfralabial distinctly larger than the other(s). Most head scales subimbricate, all smooth. Scales on nape smooth, imbricate. Three scales (considered occipitals by some authors) border the interparietal and parietals, median one rhomboid, lateral ones trapezoidal. They are mostly followed by two paravertebral series of scales, anteriorly trapezoidal, posteriad grading into dorsals, but in MPEG 13946 the second pair of scales is also separated by a median scale, and in MPEG 14111 the anterior median scale separates the two first pairs of trapezoidal scales, and there is a smaller median scale posterior to third pair. Laterally scales imbricate, smooth, with rounded posterior margin, larger in dorsolateral row, smaller on sides of neck. Gulars directly in contact with posterior chinshields, smooth, imbricate, with rounded posterior margin; in five longitudinal rows with staggered scales in adjacent rows; eight (mostly) or nine, scales along midventral row. Collar indistinct. Gular fold absent. Dorsals and scales on flanks imbricate, smooth, with rounded posterior margin, in longitudinal rows with staggered scales in adjacent rows; 25-28 (26.6 ± 0.8, n= 24) scales in a middorsal row, between interparietal and posterior margin of hind limbs. Ventrals similar to dorsals, except for pectorals which are elongate-rhomboid, and in some specimens the scales following them, which may be trapezoidal, grading posteriad into rounded scales; 15-19 (17.3 ± 1.1, n= 24) in a para-midventral row between gulars and preanals. Sixteen longitudinal rows of scales around midbody. Preanal plate with one median anterior scale, and three or five posterior scales; when five, laterals may not reach border of cloacal opening. Pores absent in females, four or five on each side in males, preanal and femoral pores indistinguishable, in a continuous row (the two rows separated medially). Pores in centre of what seems to be one three-pronged scale (or, maybe, two fused scales), with an anterior, larger part (or scale) surrounding most of the pore and ending in two blunt or pointed corners, while posteriorly a smaller part (or scale) projects a pointed extremity above the pore (fig. 169e). Scales on tail anteriorly rhomboid, smooth, imbricate, in ten longitudinal rows; on underside they are similar, but more elongate. On distal half of tail scales more pointed and, on underside, narrower and distinctly keeled, keels forming low longitudinal ridges. Regenerated tail with narrow, keeled scales. Scales on limbs smooth, imbricate; most scales with a round posterior margin, but trapezoidal, transversely enlarged, along upper posterior aspect of forearms. Scales are smallest under forelimbs, especially upper arms, and on posterior aspect of thighs, and largest under hind limbs. Subdigital lamellae single, medially swollen; 12-15 (13.3 ± 0.7, n= 47, 24 specimens) under fourth finger, 16-18 (16.7 ± 0.6, n= 46, 24 specimens) under fourth toe (Avila-Pires 1995). Colour in life: copper-brown on back, with dorsolateral stripe anteriorly salmon to pale orange, posteriorly yellowish or greenish, and blue on tail; it may be bordered dorsally by a black stripe. Flanks black. Ventral region pearl-white or with a greenish shine, with centre of most scales, especially posteriorly, black peppered. Tail mostly deep pastel blue, proximally with dorsal and lateral black stripes. Iris black. RMNH 26578 raw sienna (136) on back, with a dorsolateral stripe anteriorly yellowochre (123C), posteriorly changing to pistachio (161) and cobalt blue (168) on tail; flanks black; belly with pistachio (161) shine (description by M.S. Hoogmoed). Colour in life of MPEG 14101 was described by Nascimento et al. (1987). Other colour descriptions are given by Andersson (1918), Hoogmoed (1973), and Gasc (1990) (Avila-Pires 1995). Color in preservative: upper part of head and back chestnut-brown to olive-brown, head and back either of same colour, or head lighter or darker than back. A dorsolateral light stripe on each side from rostral (on which both stripes are connected) to tail, greenish anteriorly, gradually changing to bluish posteriad; on tail the blue becomes more intense, and distally the entire tail is blue (or brown with a bluish tinge, on regenerated tails). Flanks dark brown or black. Ventral region with a stronger or weaker bluish tinge over a blackish background. Limbs dorsally similar in colour to flanks, ventrally like belly. MPEG 2668, a juvenile, is completely brown, lighter ventrally, with a faint light dorsolateral stripe (colours probably due to discolouration in preservative) (Avila-Pires 1995). |
| Comment | The reference for Colombia (AYALA 1986) might represent the recently described species T. oriximinensis. Fitch (1968) erroneously reported T. agilis from Ecuador by misidentifying Iphisa elegans (Avila-Pires 1995). Synonymy mainly after PETERS et al. 1970. |
| Etymology | Named after Latin “agilis” = mobile, agile, swift. |
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