ROM 53608 (field number JJS 548; Fig. 1), an adult female collected by S.J.S-P., P.M.S.N., S.M.S, Liliana Saboyá-Acosta, Jhon Jairo Ospina-Sarria, Sandy B. Arroyo, and Mariane Targino Rocha in Colombia, Sierra Nevada de Santa Marta, Departamento de Magdalena, headwaters of the Río Guachacos, Corregimiento de Minca, finca Vista Hermosa, approximately 2156 m, June 2013. This locality is situated at approximately 11°05'N, 74°01'W.

Figure 1. 

Oreosaurus serranus sp. n. (holotype, ROM 53608 [70.4 mm SVL]). Dorsal, lateral and ventral views of the head, and ventral view of the pelvic region.

ROM 53609 (adult female, Fig. 2), ROM 53610 (subadult male), ROM 53611 (subadult female), ROM 53612–13 (juvenile females), and ROM 53614 (juvenile male), all with same data as holotype.

Figure 2. 

Oreosaurus serranus sp. n. (paratype, ROM 53609 [68.6 mm SVL]) in life. Photos: S.M.S (top) and Jhon Jairo Ospina-Sarria (bottom).

Oreosaurus serranus sp. n. can be distinguished from all its congeners by the number of genial pairs (1 in O. serranus sp. n. versus 2 in the other species). It also differs from all other species of Oreosaurus, except O. mcdiarmidi, by the number of supraoculars (3 in O. serranus sp. n. and O. mcdiarmidi versus 4 in the other species), and dorsal scale relief (smooth in O. serranus sp. n. and O. mcdiarmidi versus keeled or slightly keeled in the other species). Oreosaurus serranus sp. n. also differs from O. mcdiarmidi by the absence of prefrontal scales (present in O. mcdiarmidi).

Oreosaurus serranus sp. n. possesses the following characteristics: (1) maximum known SVL in males 60 mm (n = 2), in females 70.4 mm (n = 5); (2) frontonasal equal to or longer than frontal; (3) prefrontal scales absent; (4) nasoloreal suture complete [= loreal present]; (5) supraoculars three, all in contact with ciliaries; (6) superciliary series incomplete, formed only by the anteriormost superciliary scale; (7) supralabial-subocular fusion absent; (8) postoculars two; (9) postparietals two; (10) supratympanic temporals two; (11) genials in one pair; (12) dorsal scales rectangular, juxtaposed, smooth; (13) nuchal scales smooth; (14) longitudinal dorsal scale rows 10–11; (15) transverse dorsal scale rows 33–36; (16) ventral scales smooth, in 21–22 transverse scale rows; (17) lateral scale rows (oval, non-granular scales) 4–6; (18) femoral pores per hind limb in males 7–9, in females 2–3 (located proximally); (19) scales between medialmost femoral pores two; (20) subdigital scales on toe I four; (21) anterior cloacal plate scales four or six; (22) posterior cloacal plate scales seven; (23) dorsum dark brown to black with fine brown mottling; distinct dorsolateral stripes absent; lateral ocelli (i.e., white spots surrounded by dark blotches) absent (white or cream spots instead); venter black with conspicuous whitish spots mostly on scale sutures; (24) hemipenial body globose, slightly bilobed, ornamented by 14–15 chevron-shaped flounces on each side.

Adult female (Fig. 1), SVL = 70.4 mm, tail length = 72.4 mm; head scales smooth, glossy; rostral scale wider than long, higher than adjacent supralabials, in contact with frontonasal, nasals, and anteriormost supralabials posteriorly; frontonasal roughly quadrangular, longer than wide, widest posteriorly, equal in length to frontal, in contact with nasals and loreals laterally, and frontal posteriorly; prefrontals absent; frontal longer than wide, anterior suture convex, lateral sutures concave, posterior suture angular with point directed posteriorly, in contact with anteriormost supraoculars and superciliaries posterolaterally, and frontoparietals posteriorly; frontoparietals pentagonal, in contact anterolaterally with all supraoculars on the left side and second and third supraoculars on the right side, and posteriorly with parietals and interparietal; interparietal hexagonal, longer than wide, lateral sutures concave, in contact with parietals laterally, postparietals posteriorly; parietals in contact with third supraoculars anterolaterally, dorsalmost temporal and postocular scales laterally, and postparietals posteriorly; postparietals pentagonal, two, in broad contact; supraoculars three, all in contact with ciliaries. Nasoloreal suture complete, nasal quadrangular; loreal quadrangular, not in contact with second supralabial; superciliary series incomplete, formed only by the anteriormost superciliary scale, which barely extends onto dorsal surface of head, and lies between loreal, frontal, first supraocular, and anteriormost ciliaries; palpebral disc of lower eyelid divided into three large, unpigmented scales; frenocular quadrangular, in contact with loreal and nasal anteriorly; circumorbital scales between posteriormost supraocular and frenocular five; postoculars two; temporals smooth, glossy, polygonal; supratympanic temporals two; supralabials seven; infralabials four. Mental wider than long, in contact with anteriormost infralabials and postmental posteriorly; postmental roughly pentagonal, posterior suture angular with point directed posteriorly, in contact with first and second infralabials laterally; genials in one pair, roughly quadrangular, in contact with second and third infralabials; scale rows between genials and collar fold (along midventral line) eight, medialmost scales of posteriormost scale row distinctly enlarged, smooth; posteriormost gular row enfolded posteriorly, concealing one small scale row; lateral neck rounded, smooth.

Dorsal scales rectangular, longer than wide, juxtaposed, smooth, in 35 transverse rows; longitudinal dorsal scale rows at fifth transverse ventral scale row nine, at 10^th transverse ventral scale row 10, at 15^th transverse ventral scale row 11; lateral scale rows at fifth transverse ventral scale row 6/5, at 10^th transverse ventral scale row four, at 15^th transverse ventral scale row four; lateral scales on body near insertion of forelimb small to granular; ventral scales quadrangular, smooth; complete transverse ventral scale rows 22; longitudinal ventral scale rows at midbody 10; anterior cloacal plate scales six; posterior cloacal plate scales seven, medialmost scale with a horizontal suture; scales on tail rectangular and juxtaposed; midventral subcaudals smooth, wider than adjacent scales, nearly square. Femoral pores per hind limb two, located proximally; scales between medialmost femoral pores two.

In life, dorsal ground color dark brown to black with fine brown mottling; dorsal surfaces of head, body and tail with an iridescent bluish shine. White or cream spots laterally from neck to posterior portion of body, becoming less distinct posteriorly. Ventral surfaces of head and body predominantly black, with conspicuous whitish spots mostly on scale sutures; subcaudally black without spots. In preservative (70% ethanol), dorsal ground color brown with fine light brown mottling; dorsal surfaces of head, body and tail without the iridescent bluish shine. Ventral surfaces of head and body brown with cream spots on scale sutures.

Right organ of subadult male ROM 53610 (Fig. 3) was partially everted and filled. Basal and lobular regions are partially damaged. Hemipenial body is roughly globose, ending in two small and partially everted, barely visible lobes. Partial eversion and some damages precluded the detection of folds, or any other ornamentation, on the lobes.

The sulcus spermaticus, central in position, originates at the base of the organ and proceeds in a straight line towards the lobes. It is bordered by two parallel nude areas, and divided by a fleshy fold. Branches of the sulcus spermaticus are not visible. Two columns of at least 14 chevron-shaped flounces ornament the sides of the organ and the borders of the sulcate and asulcate faces of the hemipenial body. Although these flounces do not present calcified comb-like spicules, it is possible that such absence is due to the age of the specimen. These calcified structures are present in adults of most species of Cercosaurinae that have their hemipenial morphology described, including species of Oreosaurus (e.g., Kok and Rivas 2011, Nunes 2011, Rivas et al. 2005). A broad nude area occupies at least 50% of the asulcate face. Some damages at the basis of the organ precluded the detection of the isolated horizontal flounces on the proximal-central region of the asulcate face that are often present in species of Cercosaurinae (e.g., Kok and Rivas 2011, Nunes 2011, Rivas et al. 2012, Sánchez-Pacheco et al. 2011).

Figure 3. 

Oreosaurus serranus sp. n. Sulcate (left), lateral (center) and asulcate (right) views of the right hemipenis of ROM 53610 (paratype).

Paratypes consist of four females (SVL = 41.4–68.6 mm) and two males (SVL = 40.4–60 mm). The paratypes are similar to the holotype with the following noteworthy exceptions. Frontonasal longer than frontal in ROM 53609–12 and 53614; loreal scale in contact with second supralabial in ROM 53612–13; ventralmost postocular fused with posteriormost subocular on the right side in ROM 53613; medialmost scale of the posterior cloacal plate not divided horizontally in ROM 53610–11 and 53614; palpebral disc of the lower eyelid divided into two large, pigmented scales in ROM 53609; femoral pores per hind limb in female ROM 53612 three. Femoral pore number is the most evident sexually dimorphic character, with males having 7–9 pores per hind limb (ROM 53610 8/9, ROM 53614 9/7) and females having 2–3.

Oreosaurus serranus sp. n. is known exclusively from the type locality (Figs 4, 5) and San Lorenzo (Ayala and Castro unpublished data, Ayala 1986), two adjacent cloud forest localities on the northwestern slopes of the Sierra Nevada de Santa Marta (SNSM) at elevations of about 1800–2156 m (Fig. 4). This forest-dwelling lizard is often found under fallen, rotten trunks or logs. Holotype and paratypes were collected manually during the day. The new species was found at the type locality in sympatry with Anadia pulchella, another gymnophthalmid endemic to the SNSM.

Figure 4. 

Distribution of Oreosaurus serranus sp. n. in the northwestern slopes of the Sierra Nevada de Santa Marta, northern Colombia. Pentagon indicates type locality.

Figure 5. 

Type locality (top) and habitat (bottom) of Oreosaurus serranus sp. n. in the Sierra Nevada de Santa Marta, Colombia. Photos: Jhon Jairo Ospina-Sarria (top) and S.M.S (bottom).

The specific epithet serranus, which is an adjective derived from the Spanish adjective serrano (meaning from the sierra), refers to the location of the species’ type locality in the Sierra Nevada de Santa Marta, and preserves the original etymological intent of Harris, as stated by Ayala and Castro (unpublished data).

Formal nomenclatural recognition of Oreosaurus serranus sp. n. renders specularis (Ayala 1986) a permanently unavailable name for this taxon. Specimens reported by Ayala and Castro (unpublished data) were not included herein because they are presumably lost (S.J.S-P. personal observation).

Oreosaurus is one of the two genera extracted from the former Riamasensu lato, which was recently found to be non-monophyletic (Sánchez-Pacheco et al. 2017). The other clade, Andinosaura Sánchez-Pacheco et al., 2017, includes 11 Andean species and Riamasensu stricto is also an exclusively Andean radiation of 16 named species.

Sánchez-Pacheco et al. (2017) discussed the disjunct geographic distributions of species of Oreosaurus, as well as their phylogenetic relationships. Figure 6 summarizes these findings. All species of Oreosaurus share the absence of a narrow band of differentiated granular lateral scales (present in species of Andinosaura and Riama).

Figure 6. 

Summary of the phylogeny and geographic distribution of Oreosaurus (Sánchez-Pacheco et al. 2017). SNSM = Sierra Nevada de Santa Marta, Colombia; TCM = tepuis from the Chimantá massif, Venezuela; CCC = Cordillera de la Costa Central, Venezuela; IT = island of Trinidad; CCO = Cordillera de la Costa Oriental, Venezuela. Oreosaurus luctuosus, from the CCC, and O. rhodogaster, from the CCO, were included in this genus due to the presumed close relationships of these species and O. achlyens and O. shrevei, respectively. Data taken from Sánchez-Pacheco et al. (2017).