Stenocercus canastra, Ávila-Pires & Nogueira & Martins, 2019

Ávila-Pires, Teresa C. S., Nogueira, Cristiano de C. & Martins, Marcio, 2019, A new ‘ horned’ Stenocercus from the highlands of southeastern Brazil, and redescription of Stenocercus tricristatus (Reptilia: Tropiduridae), Zoologia (e 22909) 36, pp. 1-16 : 4-9

Stenocercus canastra sp. nov.

http://zoobank.org/ 3056B5B9-676D-41ED-B95E-A48FDB239241

Stenocercus cf. tricristatus ; Teixeira et al. 2016: 411, 413.

Type material. Holotype. MZUSP 88873 ( Fig. 2), an adult male, from Brazil, Minas Gerais: São Roque de Minas municipality, Parque Nacional da Serra da Canastra (PNSC) , at the beginning of the road to Casca D’Anta waterfall, 20º14’38” S, 46º32’56” W, ca 1410 m . Paratypes. Four specimens from the type-locality: MZUSP 88874 , a half-grown male; MZUSP 88875 , a female; MPEG 31738 , a male; and MNHN 2014.0061 , a male . One juvenile, MZUSP 94456 , also from PNSC, Chapadão da Zagaia , 20º09’58”S, 46º41’54” W, ca 1350 m ( Fig. 3) .

Diagnosis. Stenocercus canastra sp. nov. is characterized by the following combination of features: (1) Dorsal head scales keeled. (2) Interparietal distinct, moderately enlarged; parietals about as large as, or smaller than interparietal; postparietals large, with a prominent keel; other posterior head scales variable in size. (3) Internasals six. (4) No distinctly enlarged supraoculars, but medial ones larger than lateral ones; all with pronounced keels. (5) An enlarged canthal on each side, in contact anteriorly with two elongate scales that form a double canthal ridge. (6) An enlarged, prominent, pointed scale immediately posterior to supraciliaries; no projecting, blade-like, angulate temporal scales. (7) Gulars and ventrals distinctly keeled. (8) Parietal eye distinct. (9) Neck folds absent. (10) Dorsals phylloid, keeled, mucronate, and imbricate; scales on flanks similar to dorsals. (11) A prominent serrate vertebral crest, a slightly less prominent dorsolateral crest, and an even less prominent lateral crest. (12) Mite pockets absent. (13) Scales on posterior surface of thighs imbricate, keeled. (14) Tail nearly cylindrical to moderately compressed, verticils absent. (15) Dorsal coloration with numerous, bold, dark brown rhomboid marks forming a longitudinal series on back, and dark brown vertical bands on flanks; head with at least a dark brown spot between nostrils, and a large, rhomboid spot between eyes; no sexual dimorphism in color pattern. (16) Scales around midbody 39–41, ventrals between anterior margin of forelimbs and anterior margin of hind limbs 25–28. (17) Ear opening bordered anteriorly by a distinctly enlarged, smooth scale. Stenocercus canastra sp. nov. is distinguished from all other Stenocercus except S. dumerilii , S. tricristatus , S. quinarius and S. squarrosus by the presence of an enlarged, prominent post-supraciliary scale ( Figs 5–9); from all others except S. tricristatus , S. quinarius and S. squarrosus by a moderately enlarged interparietal (although not as large as in the Tropidurini; Figs 10–11). It is distinguished from S. dumerilii , S. quinarius and S. squarrosus (character states in parentheses) by the presence of a prominent, serrate vertebral crest (in contrast to a low vertebral crest); two, rarely 3, supraciliaries (4, rarely 3); ear-opening bordered anteriorly by a distinctly enlarged scale projecting over tympanum (no enlarged scale projecting over tympanum; Figs 12–17); dorsals distinctly keeled and mucronate (dorsals with a low keel, not or hardly mucronate); 9–10 scales across midbody from one dorsolateral row to the other (11–13 in S. dumerilii , 13–15 in S. quinarius and S. squarrosus ); ventrals between anterior level of fore- and hind limbs 24–28 (28–32 in S. dumerilii , 30–34 in S. quinarius , 28–34 in S. squarrosus ); scales on chin subequal and imbricate, or only most anterior ones smaller and subimbricate (scales on chin smaller, polygonal, and subimbricate anteriorly, grading into larger, pointed, and imbricate posteriorly; Figs 18–22); tail 1.4–1.8 times SVL (1.2–1.4 times in S. dumerilii , 1.0– 1.1 in S. quinarius and 0.8–0.9 in S. squarrosus ); and color pattern (Table 1). From S. tricristatus it differs in presenting head width 0.78–0.89 times head length (0.96); 39–41 scales around midbody (33); and ear-opening bordered anteriorly by a distinctly enlarged, smooth scale (scale not larger than adjacent temporal scales, keeled). Moreover, it probably reaches a larger body size (adult males ≥ 70 mm in S. canastra sp. nov. versus 58 mm in the holotype of S. tricristatus ).

Description. Tropidurid with a known maximum SVL in males of 77 mm ( MZUSP 88873, holotype), and 65 mm in the only female known ( MZUSP 88875). Head 24–25% of SVL, 1.1– 1.2 times as long as wide, 1.2–1.3 times as wide as high. Snout bluntly pointed. Canthus rostralis well defined, continuous with supraciliaries, which end in an enlarged, prominent scale, so that the head has the shape of a four-sided pyramid. Neck narrower than head and body. Body roughly cylindrical. Limbs well developed, forelimbs 42–46% of SVL, hind limbs 58–65% of SVL, tibia 15–17% of SVL. Tail nearly cylindrical to slightly compressed, 1.7–1.8 times SVL in the largest specimens ( SVL 71–77 mm), 1.4–1.5 in the smallest specimens ( SVL 42–65 mm).

Rostral roughly triangular, largest width three to four times the medial height, only barely visible from above. Postrostrals 4–5. Snout, supraocular, and interorbital regions covered with irregularly polygonal, subimbricate to juxtaposed, strongly keeled scales, heterogeneous in size. Six scales between nasals, of which one supranasal at each side and four scales between them. Scales across the snout between canthals 3–5 (minimum number in a transverse row). One large canthal on each side, anteriorly in contact with two elongate, keeled scales (one of which is the supranasal); canthal posteriorly in contact with the first supraciliary. Supraorbital semicircle formed by 7–8 scales (between canthal ridge and post-supraciliary scale), of which the third and fourth, or only the fourth, are in medial contact; the posterior scale is the largest and most prominent, the second most anterior scale is often the second largest. Supraoculars irregularly polygonal, subimbricate, strongly keeled, none distinctly enlarged; 3–5 in a transverse line across the greatest width of each orbit. Two (three on the left side of MPEG 31738) elongate supraciliaries in contact with each other (narrowly overlapping), with a third supraciliary lateral to, and in contact with, the other two. Canthals and supraciliaries form a distinct ridge that ends in a very prominent pointed scale immediately posterior to supraciliaries; in the juvenile, MZUSP 94456, this scale is less prominent. This ridge delimits a sharp angle between dorsal and lateral surfaces of head. Interparietal moderately enlarged, roughly rhomboid or hexagonal, parietal eye distinct. Parietals about as large as, or smaller than interparietal; in some specimens separated from interparietal by small scales. Postparietals large with a prominent keel, separated medially by small scales (in medial contact in MNHN 2014.0061). Other posterior head scales heterogeneous in size. Angulate temporals distinctly keeled, but not especially large or prominent ( Fig. 10).

Nasals lateral to canthal ridge, undivided, separated from rostral by the postrostrals; nostril in posterior part of nasal, directed latero-posteriorly. Loreal region with a distinct row of lorilabials, anteriorly and posteriorly forming a single row of scales, medially a double row; between lorilabials and canthal ridge a few large (and in some cases a few small as well), irregularly polygonal scales, with small keels and/or variably rugose surface. Scales in a transverse row between canthal and supralabials, 4–5. An elongate subocular, preceded by a distinctly shorter pre-subocular, both keeled, the keels aligned and closer to the upper margin of the scales. Elongate subocular separated from supralabials by the row of lorilabials. Supralabials 5–6, very narrow and mostly with a keel on their lower margin. Temporal region with polygonal (mostly rhomboid to hexagonal), strongly keeled, imbricate scales, in approximately oblique rows; upper scales larger and distinctly more prominent (these scales are ventral to what was called by Cadle 1991 “angulate temporals”). Ear opening vertically oval, largely covered by an enlarged, smooth scale on its anterior margin; tympanum slightly recessed ( Figs 5, 12, 13).

Mental relatively small, but larger than adjacent infralabials and the two or four post-mentals. Infralabials 5–7 (mostly 6), very narrow and keeled; followed by a relatively large, elongate, keeled scale. Scales on chin anteriorly polygonal, keeled, subimbricate, posteriorly (including gulars) mostly phylloid, distinctly keeled, mucronate, and imbricate, longer and with higher keels laterally. The keels of the phylloid scales are mostly aligned in longitudinal rows, which also continue along neck and belly; anteriorly on the chin these rows converge towards the mental. Gulars between ventral edges of ear-openings 11–14 (12.7 ± 1.0). No gular or lateral folds ( Fig. 18).

Scales on nape relatively small, subimbricate, and keeled medially, dorsolaterally similar to dorsals but shorter, some of them with a very prominent mucron. On sides of neck the mucron is similarly well developed, giving the neck a spinose appearance. Dorsals phylloid, keeled, mucronate, and imbricate, in approximately longitudinal rows. A prominent serrate vertebral crest of moderately enlarged, strongly keeled, and mucronate scales is present from nape to base of tail. A dorsolateral row of similar, but slightly smaller, scales on each side forms a lower, serrate crest also from nape to base of tail. A third, less prominent longitudinal crest, is present on each side, between fore- and hind limbs. Vertebral and dorsolateral crests usually separated by three scales in a transverse line at midbody, totaling nine scales from one dorsolateral crest to the other (10 scales in MZUSP 88875); dorsolateral and lateral crests are separated by 4–5 rows of scales. Vertebral crest with 25–28 (26.2 ± 1.1) scales from occiput to posterior margin of hind limbs. Paravertebral scales between the same points 36–42 (39.7 ± 2.3). Ventrals similar to dorsals, but flatter and slightly larger, forming distinct longitudinal rows (the keels forming low longitudinal ridges); 24–28 (25.9 ± 1.5) ventral scales along a midventral line between anterior level of forelimbs and anterior level of hind limbs. Scales around midbody 39–41 (39.7 ± 0.8). Scales on preanal plate similar to dorsals, but slightly smaller. Mite pockets absent.

Scales at base of tail similar to dorsals and ventrals. Distally the scales grade into polygonal shapes and become arranged in transverse (slightly oblique) rows; the crests disappear, but the ridges formed by the keels, on the ventral surface, continue to the tip of the tail. No distinct verticils (which probably indicates that autotomic segments are absent).

Limbs with phylloid, strongly keeled, mucronate, and imbricate scales, similar to, or smaller and more elongate than, dorsals. The mucron is especially well developed on the upper aspects of hind limbs. Subdigital lamellae single, mostly tricarinate; 13–15 (14.0 ± 0.8) under fourth finger, 17–20 (19.0 ± 1.2) under fourth toe.

In life, ground color predominantly light brown, with several dark brown blotches. Borders of most of blotches deep dark brown followed by white to cream areas ( Fig. 2). Main features are: (1) an irregular dark brown blotch on anterior part of snout, present or absent; (2) a very conspicuous, large, rhomboid dark brown blotch on posterior part of snout and anterior to supraocular region, present in all individuals; it may be irregularly bordered by a thin white line; (3) posteriorly, on post-parietal and supratemporal areas, either three relatively large, irregular dark brown blotches (medial one may have a shape grossly reminding of a butterfly), or four small dark brown blotches; (4) sides of head with a brown oblique band, bordered by dark brown, from below the eye to supralabials, and in some specimens one or two other similar bands posteriorly; (5) a series of 6–9 roughly triangular or rhomboid (a few irregular) dark brown spots along the vertebral region, from nape to level of hind limbs; intermediate dorsolateral spots are usually present; (6) sides of neck and flanks with irregular brown bands bordered by dark brown, usually separated by cream to light brown areas; (7) brown to dark brown spots form irregular bands across both limbs and tail, separated by wider (tail) or narrower (limbs) light brown spaces. Ventral region immaculate, dirty white to tan. In preservative, all colors tend to become darker.

Holotype main features. SVL 77 mm, tail length 132 mm, head length 19.0 mm, head width 16.7 mm, head height 13.6 mm, fore limb length 33 mm, hind limb length 45 mm, tibia length 12.5 mm. Scales around midbody 40. Vertebrals (from occiput to posterior margin of hind limbs) 27. Ventrals (between anterior margin of forelimbs and that of hind limbs) 28. Lamellae under fourth finger 15, under fourth toe 20. See also Figs 2, 5, 10, 13, 18.

Distribution. Stenocercus canastra sp. nov. is only known from Serra da Canastra National Park, Minas Gerais, Brazil ( Figs 23–24). Besides the type series, two additional individuals of S. canastra sp. nov. were observed, but not collected, in an area very close to (less than 1 km N) the type-locality (O. Marini, pers. comm.).

Etymology. The specific epithet canastra is a noun in apposition and refers to the mountains (‘Serra da Canastra’) where all specimens were collected.

Habitat and natural history. These lizards were found in two localities 18 km apart, at Serra da Canastra National Park, in Minas Gerais, southeastern Brazil. Elevation varies from 800 to 1507 m. The vegetation is characterized by savanna-like ‘cerrado’, grass/shrubland on deep, well-drained soil (‘campo limpo’ and ‘campo sujo’) and on rocky, shallow soils (‘campos rupestres’), and narrow strips of riparian forests. Dietz (1984) gives a general description of the vegetation in the area. Stenocercus canastra sp. nov. was only found in open cerrado formation with dense grass vegetation on deep, well-drained soil, between 1350–1410 m. It was not found in areas with rocky quartzitic soil/sandy soil and on rock outcrops, which cover a large portion of the park. Six specimens were on or inside termite mounds – all six found in about one hour, after a fire. The juvenile was obtained in a pitfall trap in campo limpo. Scales of S. canastra sp. nov. were found in scats of the omnivorous maned wolf ( Canidae ), Chrysocyon brachyurus (Illiger, 1815) ( Queirolo and Motta-Junior 2007) .

Stenocercus tricristatus (A. Duméril, 1851) Ophryoessoides tricristatus A. Duméril (in Duméril and Duméril 1851):

66 (holotype MNHN 6825, type-locality: ‘Brésil’); Duméril et al.

1854: 267; A. Duméril, 1856: 531; Etheridge 1966: 89; Peters and Donoso-Barros 1970: 215 (part); Fritts 1974: 35 (part). Liocephalus tricristatus ; Boulenger 1885: 170. [ Stenocercus ] tricristatus ; Frost 1992: 43 (part). Stenocercus tricristatus ; Torres-Carvajal 2007a: 161, 2007b: 317. non Ophryoessoides tricristatus ; Cunha 1981: 4.

Material examined. Holotype, MNHN 6825 , M, Brazil, leg. Claussen.

Diagnosis. Stenocercus tricristatus is characterized by the following combination of features: (1) Dorsal head scales keeled. (2) Interparietal distinct, moderately enlarged; posterior head scales variable in size. (3) Internasals six. (4) No distinctly enlarged supraoculars. (5) An enlarged canthal at each side, in contact anteriorly with two elongate scales that form a double canthal ridge. (6) An enlarged, prominent, obtusely pointed scale immediately posterior to supraciliaries; no projecting, blade-like, angulate temporal scales. (7) Gulars and ventrals distinctly keeled. (8) Parietal eye distinct. (9) Neck folds absent. (10) Dorsals phylloid, keeled, mucronate and imbricate; scales on flanks similar to dorsals. (11) A moderately prominent, serrate vertebral crest, and a slightly less prominent dorsolateral crest (a less conspicuous lateral crest may be present, but it is not very clear from the present condition of the specimen). (12) Mite pockets absent. (13) Scales on posterior surface of thighs imbricate, keeled. (14) Tail moderately compressed, verticils absent. (15) Dorsal coloration probably with numerous dark brown spots on back and flanks; head with at least a large, triangular spot on posterior part of snout. (16) Scales around midbody 33, ventrals between anterior margin of forelimbs and anterior margin of hind limbs 23. (17) No distinctly enlarged scale on anterior margin of ear-opening.

Stenocercus tricristatus is distinguished from all other Stenocercus except S. canastra sp. nov., S. quinarius , S. squarrosus and S. dumerilii by the presence of an enlarged, prominent post-supraciliary scale; from all others except S. canastra sp. nov., S. quinarius and S. squarrosus by a moderately enlarged interparietal (although not as large as in the Tropidurini). It is distinguished from S. dumerilii , S. quinarius and S. squarrosus (character states in parentheses) by the presence of a prominent, serrate vertebral crest (in contrast to a low vertebral crest); two supraciliaries (4, rarely 3); absence of two distinctly enlarged upper temporals (two distinctly enlarged upper temporals); preauricular scale projecting over the tympanum, keeled (preauricular scale not or only slightly projecting over the tympanum, smooth); dorsals distinctly keeled and mucronate (dorsals with a low keel,