Sceloporus aurantius sp. nov.

Sceloporus scalaris (part): (McCranie & Wilson 2001): 20.

Sceloporus scalaris (part): (Vázquez-Díaz & Quintero-Díaz 2005): 155. Sceloporus scalaris brownorum (part): Smith et al. 1997: 290.

Sceloporus scalaris brownorum (part): Watkins-Colwell et al. 2006: 814.1. Sceloporus scalaris brownorum (part): Bryson et al. 2012: 448.

Sceloporus scalaris brownorum (part): Grummer et al. 2014: 120.

Holotype. MZFC 28392 (field number RWB 1042; Fig. 4). Adult female. Mexico: Aguascalientes: Municipio Calvillo, Los Alisos, Sierra del Laurel (N 21°43’32.2”, W102°42’01.4”; 2419 m). 20 July 2010. Robert W. Bryson, Jr.

Paratypes. Thirteen specimens. Mexico: Aguascalientes: Same locality as the holotype. 20 July 2010. Robert W. Bryson, Jr., José Carlos Arenas-Monroy, and Michael Torocco. MZFC 25101–25106 (field numbers RWB 1019–1024). Four adult females, two adult males (Fig. 5). Ciénega [Sierra del Laurel] (N 21°45’0.0”, W 102°43’01.2”; 2370 m). 4 August 1979. Larry Wilson. USNM 346561–346564. Two adult females, two adult males. Jalisco: 1 mi NE Villa Hidalgo [foothills of the Sierra del Laurel]. 24 October 1950. KUH 29636. Juvenile male. Zacatecas: Ojo de Agua, 2.5 km NW Rancho Los Adobes (N 21°44’53.86”, W 103°29’42.9”; 2140 m). 27 April 2008. Iván T. Ahumada Carrillo. MZFC 24818. Adult male (Fig. 6). 3.4 km S La Estancia (N 21°41’44.2”, W 103°28’56.1”; 2228 m). 26 May 2008. Iván T. Ahumada Carrillo. MZFC 24831. Adult male.

Diagnosis. Sceloporus aurantius sp. nov. belongs to the S. scalaris species group, sharing with other species in that group the following characters: parallel lateral scale rows (except in S. goldmani), femoral pore series in contact or separated by no more than two scales, females with smooth preanal scales, and males with lateral abdominal color patches (Smith 1939; Smith et al. 1997; Watkins-Cowell et al. 2006). Sceloporus aurantius sp. nov. differs from all S. scalaris group species except S. chaneyi by the lack of blue belly bars in adult males. Sceloporus aurantius sp. nov. differs from S. chaneyi in adult size (mean snout-to-vent length 49.8 mm vs. 45.7 mm), number of dorsal scales (mean of 39.2 vs. 42.3), number of scales around midbody (mean of 37.9 vs. 40.4), and presence of an un-patterned morph (absent in S. chaneyi). Although not a diagnostic character state, Sceloporus aurantius sp. nov. further differs from S. chaneyi, and all other species in the S. scalaris species group, by unique phylogenetic position revealed through species delimitation (Grummer et al. 2014; Fig. 2).

Description of holotype. Adult female (Fig. 4). SVL 55 mm, 117 mm with tail. Head length 11.05 mm. Tibia length 10 mm. Entire hind limb length (including 4th toe) of 24 mm. Forelimb length 13 mm. Dorsal head scales keeled and rugose. Five internasals of irregular shape. Canthals 2–2 (right–left). Loreals 1–1. Supralabials 5–5. Infralabials 6–5. Postnasals 2–2, irregular. Preoculars 1–1 with a strong transverse keel on posterior margin. Five frontonasals, keeled. Two prefrontals, rugose and keeled with medial contact posteriorly, divided by a frontonasal anteriorly. One frontal transversely divided, rugose, with two keels on lateral margins. Interparietal coronate with posterior notch. Frontoparietals 2–2. Parietals 2–2, rugose. Two complete lorilabial rows. Dorsal scales keeled, acuminate, smooth (not serrate). Thirty-nine dorsal scales. Parallel lateral scale rows on body. Scales around midbody 38. Ventral scales rounded with posterior notch.

Pale vertebral stripe two scales wide. Two pale dorsolateral stripes approximately ½ scale wide, interspersed with dark flecks. Vertebral and dorsolateral stripes separated by three scale rows. Two pale lateral stripes ½ scale wide, separated from dorsolateral stripes by two scale rows. Chevrons in four rows between each pair of dorsal stripes; 7 between left lateral and dorsolateral stripes, 12 between left dorsolateral and vertebral stripes, 12 between vertebral and right dorsolateral line, 8 between right dorsolateral and lateral stripes. Chevrons are dark with scales’ posterior margins pale. Dorsolateral and ventral surfaces pale with minute dark flecks throughout. Gular region lacking distinct markings.

Color in preservative. Dorsal and lateral portions of head brown with white between ocular and opercular openings; white loreal scales. Underside of head is white with small black flecks. Two white dorsolateral lines (~1 scale wide) and a broad (~3 scales wide) light gray vertebral stripe fading into base of tail. Numerous black chevrons with white posterior margins, between vertebral and dorsolateral stripes. Scales between chevrons are brown. A single white line (~1 scale wide) extends from posterior portion of operculum to inguinal area where the femur joins the body on the lateral portion of the belly, separated from dorsolateral line by black chevrons with brown scales between. Front and hind limbs are brown with black, grey, and white scales scattered throughout. Proximal dorsal portion of tail with black and grey scales on a grey/brown background. Distal portion of tail is brown. Undersides of limbs, venter, and tail are white with sparsely distributed small black flecks. Chin and throat without distinct black or grey streaks or bars.

Color in life. Head: brown/rust on dorsal portion, grey-brown on sides in front of and below eyes. Dorsum with two cream-colored dorsolateral lines and dark grey vertebral stripe. Black chevrons in between vertebral and dorsolateral lines, with posterior margins of dark scales containing white margins. Portions between chevrons are rust/brick red. On each side of the belly, a white line (~1 scale wide) extends from head to femur as described above. Lateral scales between white lateral line and ventral scales are light red/brown. Front limbs grey with a black shoulder spot. Hind limbs grey with faint black bars lined with white on posterior edges. Proximal dorsal portion of tail with black triangles; distal dorsal portion brown.

Morphometric variation. Adults only. Includes 7 females and 6 males. Snout-vent length 48–55 mm (x =50.85; SD=3.41). Head length (snout to posterior edge of interparietal) 9.6–11.35 mm (10.68 mm; 0.55). Tibia length (left side) 9–10.5 mm (9.46 mm; 0.52). Entire hind limb length (including fourth toe) 22–26.5 mm (23.46 mm; 2.08).

Scalation variation. Includes 7 females and 7 males. Dorsal scales range 37–43 (x̅=39.21; SD=1.72). Scales around midbody 35–42 (37.93; 1.82). Ventral scales 35–46 (42.21; 2.81). Canthals 2–2 (LR; 14/14). Frontonasals 3–4 (3.36; 0.74). Supralabials 5–5 (LR; 12/14), 6–5 (1/14), 6–6 (1/14). Infralabials 5–6 (1/14), 6–6 (5/14), 7–6 (2/ 14), 7–7 (6/14). Preoculars (missing data from one damaged specimen, USNM 346564) 1–1 (10/13), 1–2 (1/13), 2–2 (2/13). Loreals (missing data from USNM 346564) 1–1 (1/13), 1–2 (1/13), 2–1 (1/13), 2–2 (6/13), 2–3 (2/13), 3–2 (1/13), 3–1 (1/13). Frontoparietals 2–4 (2.64; 0.84).

Coloration variation. In life, lateral edge of body and venter with orange streak in males, becoming less distinct at midbody towards back leg (Figs. 5–6). A male paratype (USNM 346561) was elsewhere described in life as having an orange-colored side with cream spotting below the lateral line (McCranie & Wilson 2001). This orange streak is not apparent in preservative. A pattern-less morph occurred in both males and females. One male (MZFC 24831) had some dark mottling on chin.

Etymology. The specific epithet is formed by the Latin adjective aurantius, which means “orange colored”, in reference to the orange dorsolateral streak of males. As common names we suggest Southern Occidental Bunchgrass Lizard (English) and Lagartija de Pastizal Sur Occidental (Spanish).

Distribution. Known from the oak forests of the Sierra del Laurel in southwestern Aguascalientes and southern Zacatecas (Fig. 1). However, we suspect that S. aurantius sp. nov. may be more widespread across the southern sky islands of the Sierra Madre Occidental. Unfortunately, because females are difficult to distinguish from other regional species of bunchgrass lizard, we could not confidentially ascertain whether the female specimens from this region (LSUMZ 35078, 35108; and UTEP 6504–6506) are S. brownorum (as currently designated in Smith et al. 1997) or S. aurantius sp. nov.

Natural history. Most of the type series (MZFC 25101–25106, 28392) were collected on 20 July 2010 throughout the day in patches of bunchgrass within oak forest (Fig. 7). Four females contained well-developed eggs. The two specimens from southern Zacatecas were collected in oak forest.