Loxopholis guianense (RUIBAL, 1952)
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|Higher Taxa||Gymnophthalmidae (Ecpleopodinae), Sauria, Gymnophthalmoidea, Squamata (lizards)|
|Common Names||Portuguese: Briba, Calango, Lagartixa|
|Synonym||Leposoma guianense RUIBAL 1952: 489|
Leposoma guianense — PETERS et al. 1970: 165
Leposoma guianensis — GASC 1990
Leposoma guianense — HOOGMOED & AVILA-PIRES 1991: 81
Leposoma guianense — AVILA-PIRES 1995: 389
Leposoma guianense — RODRIGUES & AVILA-PIRES 2005
Leposoma guianense — RIBEIRO-JUNIOR & AMARAL 2016
Loxopholis guianense — GOICOECHEA et al. 2016
Loxopholis guianense — MARQUES-SOUZA et al. 2022
|Distribution||Guyana, French Guiana, Suriname, Brazil (Amapa, Para, NE Amazonas)|
Type locality: Dunoon, Demerara River, Guyana.
|Types||Holotype: UMMZ 46770|
|Diagnosis||Diagnosis. Leposoma with a very large interparietal, with diverging lateral margins. Supralabials followed by a scale distinctly larger than adjacent temporals. Suture between prefrontals long, between frontoparietals shorter. Fourth pair of chinshields moderately large. Dorsals mostly from hexagonal (wider posteriorly) middorsally, to phylloid toward flanks; 30-35 (32.6 ± 1.2) along a middorsal row. Ventrals 19-25 (21.7 ± 1.0) along a midventral row. Scales around midbody 23-26 (23.8 ± 0.8). Flanks usually slightly darker than back, but not forming a distinct dark lateral band; an upper dark stripe may be present (Avila-Pires 1995).|
Description. Gymnophthalmid with maximum SVL in males of 37 mm, in females of 39 mm (Hoogmoed, 1973). Head 0.20-0.25 (n= 57) times SVL, relatively larger in smaller specimens, and in adult males as compared to adult females; 1.4-1.6 (1.51 ± 0.05, n= 57) times as long as wide; 1.1-1.6 (1.34 ± 0.10, n= 57) times as wide as high. Snout short, blunt, sloping gently toward top of head. Neck slightly swollen anteriorly. Body cylindrical. Limbs well developed, forelimbs 0.26-0.33 (0.28 ± 0.01, n= 55) times SVL, hind limbs 0.36-0.48 (0.42 ± 0.02, n= 55) times. Both limbs tend to be slightly larger in smaller specimens. Tail round in cross section, tapering toward tip, 1.4-1.9 (n= 31) times SVL, relatively longer in larger specimens.
Tongue lanceolate, covered with imbricate, scale-like papillae, with a smooth, bifid tip. Anterior teeth conical, posterior teeth mostly bicuspid, occasionally tricuspid.
Rostral approximately trapezoid, more than twice as wide as high. Frontonasal single, irregularly pentagonal, laterally in contact with nasal and loreal. Prefrontals quadrilateral (the pair resembles a stylised butterfly, wider anteriorly), longer than wide, with a long medial suture. Each laterally in contact with first supraocular, loreal (usually), and in some specimens it touches second supraocular. Frontal hexagonal, longer than wide, anteriorly as wide as, or slightly wider than posteriorly; in contact with first (usually), second, and (occasionally) third supraoculars. Frontoparietals irregularly pentagonal, longer than wide, medial suture shorter than that between prefrontals; laterally in contact with third and fourth, occasionally also second, supraoculars. A very large interparietal, with lateral margins divergent posteriad. Parietals distinctly shorter and narrower than interparietal. Posterior margin of interparietal and parietals roughly form a semicircle. Occipitals absent. Four supraoculars, second and third largest, subequal. Supraciliaries 3-6, usually four; first widest. Nasal usually undivided, rarely semidivided. Nostril in its anterior part, directed laterally. Loreal rectangular, usually separated from supralabials by a distinct suture between frenocular and nasal, exceptionally in contact with them. In a few specimens loreal divided into two scales (note that what is called by Uzzell & Barry, 1971 as "loreal divided" represents here the loreal plus frenocular). Frenocular followed by a series of 5-8 suboculars, and 3-5 postoculars. At least upper postoculars keeled; the uppermost one borders on parietal. Lower eyelid with a semitransparent disc of 3-5 palpebrals. Six, rarely seven, supralabials, posterior largest, one before last below centre of eye; they are followed by a large postsupralabial. Temporal scales variably polygonal, subimbricate, keeled, larger toward parietals. Ear-opening relatively large, vertically oval, surrounded by small scales which anteriorly form a finely lobed margin, posteriorly a smooth margin. Tympanum almost superficial. All dorsal and lateral head scales, except for temporals, juxtaposed. Scales on dorsal surface of head with irregularly undulating longitudinal striations. On the sides, temporals and postoculars keeled, other scales smooth.
Mental approximately semicircular. Postmental pentagonal or heptagonal, single, except in MPEG 15083 in which it is longitudinally divided medially. Four pairs of chinshields, second largest, fourth distinctly smaller than the others. First and second pairs in contact medially and with infralabials, third pair separated medially by one or two small scales, and separated from infralabials by one scale. Scales of fourth pair closer to each other than to infralabials, separated from each other by two or three scales, from infralabials by three to five scales. Four, occasionally five, infralabials, suture between third and fourth below centre of eye. Infralabials followed by one to three, mostly two, narrower (except, in some specimens, the anterior one) postinfralabials. Most head scales covered with small pits, which either form a peripheral row (posterior dorsal head scales) or are scattered over the entire surface (others).
Scales on nape rhomboid, keeled, imbricate, posteriorly grading into dorsals. Scales on sides of neck conical to shortly trihedral, juxtaposed to subimbricate, in approximately vertical rows. At level of collar scales may be slightly larger, flattened, and keeled. Gulars imbricate, anteriorly squarish and weakly keeled, posteriad becoming larger, longer than wide, strongly keeled, and mucronate; in 8-11, mostly nine, transverse rows. Collar rather indistinct, with 8-11 scales. Gular fold distinct toward sides. Gulars separated from scales on chin by a row of granules.
Dorsals and scales on flanks imbricate, keeled, mucronate, in transverse and oblique rows; toward middorsal line approximately hexagonal, most scales widening posteriad, toward flanks they gradually become phylloid; 30-35 (32.6 ± 1.2, n= 53) transverse rows of dorsals between interparietal and posterior margin of hind limbs. Ventrals imbricate, in the shape of a heraldic shield, low and broadly keeled, shortly mucronate; in six or eight longitudinal, and 19-25 (21.7 ± 1.0, n= 53) transverse rows; keels longitudinally aligned. Scales around midbody 23-26 (23.8 ± 0.8, n= 53). Scales on flanks and ventrals resemble each other more the closer they are. Preanals variable, with four or five elongate scales, four elongate scales plus one small mid-posterior scale, one mid-anterior scale plus three to five (mostly five) posterior scales, or rarely three anterior and five posterior scales. Males with two preanal pores and 4-6 femoral pores at each side (femoral pores in total 9-12, 11.0 ± 1.0, n= 27). Females with none or one (most commonly) preanal pore at each side, and no femoral pores; INPA 150 with two preanal and one femoral pores at each side. Pores in centre of a swollen area formed by three or four scales, anterior one largest.
Tail with imbricate, squarish, keeled, shortly mucronate scales, in transverse and longitudinal rows, keels aligned longitudinally. On underside scales similar but narrower, roof-shaped, forming low longitudinal ridges along the tail.
Scales on limbs mostly rhomboid, keeled, imbricate. Smaller, tuberculate, subimbricate, on ventral aspect of upper arms, and most of dorsoposterior aspect of thighs, but on posterior aspect of thighs some scales are larger and flatter. Subdigital lamellae medially divided; 9-12 (10.3 ± 0.7, n= 105, 53 specimens) under fourth finger, 14-17 (15.3 ± 0.8, n= 103,53 specimens) under fourth toe (Avila-Pires 1995).
Colour in life of dorsal surface of head and back hair-brown (119A), sepia (219), or raw-umber (223). Dorsolateral stripe raw-umber (23) or sayal-brown (223C), bordered on both sides or only ventrally by sepia (119). Ventral region in adult males completely or mostly peach-red (94) or chrome-orange (16); gulars may be flesh-colour (5); centre of belly may be dirty-white or whitish with a peach-red or orange hue. In adult females and juveniles ventral region cream. Colour of tail similar to that of body. Iris redish-brown, or greyish-brown with a wide reddish-brown rim around pupil (Avila-Pires 1995).
Color in preservative: back and flanks brown. Blackish flecks may be present on back. A dorsolateral light stripe on each side from neck to base of tail, fainter near mid-body. The light stripe may be bordered, on one or on both sides, by a blackish, dotted or continuous line, which laterally may form a continuous blackish stripe about as wide as the light stripe. Flanks slightly darker than back; a few roundish, light spots, with faint dark borders, may be present on sides of neck and close to forelimbs. Ventral region cream, spotless except in some specimens ventrolaterally; labials with transverse dark brown bands. Limbs brown dorsally, cream ventrally. Tail predominantly brown dorsally and laterally, with irregular blackish spots middorsally (proximally) and laterally. A n ill-defined pair of dorsolateral light stripes continues from body, and some distance from base it converges and fades out. Ventrolaterally a longitudinal row of light spots at each side of tail. Ventral surface of tail predominantly cream, peppered with brown (Avila-Pires 1995).
|Comment||Distribution: For a map of localities see Marques-Souza et al. 2022.|
|Etymology||Named after the type locality.|
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