Lepidophyma lusca Arenas-Moreno & Muñoz-Nolasco & Moral & Rodríguez-Miranda & Domínguez-Guerrero & Méndez-De La Cruz 2021, sp. nov.

Lepidophyma lusca, sp. nov.

(Figs. 3–5)

Lepidophyma gaigeae Ahumada-Carrillo (2013)

Holotype: (CNAR IBH 32556), adult female collected on the banks of the Gallinas river, Tamul waterfall, 4.4 km SW from the locality of Tanchachín, municipality of Aquismón, San Luis Potosí, Mexico (21.804°, -99.180°; 195 m elev.). Collected by Arenas-Moreno, D.M., Bautista-del Moral A., and Rodríguez-Miranda L.A. on 2 nd May 2019.

Paratypes: Eleven specimens, all from the same region as the holotype. All specimens collected were adults (CNAR IBH 32554-55, 32557-65).

Etymology: The specific epithet, “lusca”, is the singular feminine noun in Latin for “one eyed”, due the absence of parietal eye.

Diagnosis: Lepidophyma lusca sp. nov. can be easily distinguished from the syntopic species L. occulor by its smaller size (maximum SVL in L. lusca sp. nov. 53.16 mm vs. 125.3 mm in L. occulor); smooth scales with reduced dorsal tubercules (enlarged and conspicuous dorsal tubercules in L. occulor); fewer gular scales (up to 38 in L. lusca sp. nov. and at least 58 in L. occulor); absence of parietal spot (present in L. occulor). Lepidophyma lusca sp. nov. is similar in morphology to L. gaigeae (sister species) and the species of Tehuantepec A clade (L. cuicateca, L. dontomasi, L. lowei, and L. radula; Noonan et al. 2013), given its small body size, reduced tubercular scales and slightly differentiated caudal whorls and interwhorls. This species differs from L. cuicateca, L. dontomasi, L. gaigeae, L. lowei, and L. radula in lacking parietal spot; in have more than one gular scale contacting the first two infralabials in some individuals (no more than one gular scale contacting the first two infralabials in L. cuicateca, L. gaigeae, and L. lowei; zero in L. dontomasi and L. radula); from L. cuicateca and L. gaigeae in that the caudal interwhorls are not complete ventrally (complete in L. cuicateca and L. gaigeae); from L. cuicateca, and L. lowei in have less than 137 dorsal scales (more than 150 in L. cuicateca and more than 158 L. lowei); in have 26 or less femoral pores (27 or more in L. gaigeae), and shorter head length and width than L. gaigeae (Tables 2 and 3).

Description of the holotype: an adult female; snout-vent length 48.53 mm; tail length 56.57 mm; axilla groin length 25.7 mm; head length 11.73 mm; head width 6.27 mm; head depth 4.39 mm; orbit length 1.74 mm; fourth toe length 6.68 mm. Rostral followed by nasals, in contact with median frontonasal; two prefrontals; two frontoparietals; no frontal; interparietal scale without parietal spot, and two parietals at the sides. Nostril bordered by nasal, postnasal and supralabial; postnasal followed by two loreals, the anterior loreal higher than postnasal and smaller than posterior loreal. Eight supralabials, the sixth bigger than the others and the fifth in contact with the orbit; six infralabials, the second and third being larger and the sixth the smallest. Two postoculars in contact with the sixth supralabial. Three supratemporals; first supratemporal divided in contact with parietal, second supratemporal larger than the others in contact with parietal and occipital, and third supratemporal in contact with occipital. Seven enlarged pale auriculars, border the anterior part of tympanic opening. Two gulars contacting first infralabial; 37 gulars along the ventral midline between second pair of infralabials and posterior gular fold (Figs. 3 and 4). The body surface in dorsal view covered by small granular scales of different size, interspaced with slightly enlarged and keeled tubercles, each followed by one or more granular scales of heterogeneous size; 18 large paravertebral tubercles from above axilla to above groin in the paravertebral row. The vertebral area with small tubercles with three paravertebral rows, these rows start under the groin and are getting loss in the middle of dorsum; 131 dorsals along the middle line between the posterior edge of postparietals to the vent. Quadrangular ventrals smooth and flat, 10 rows at mid body; the rows at the edges smaller and slightly keeled and elevated; 37 transversal rows of ventrals between gular fold and vent (including three rows of preanals). Scales on ventral surface of limbs heterogeneous in size and slightly keeled; 20 femoral pores (9/11); 26 scales on the fourth toe, excluding the claw. Tail with complete enlarged whorls like rings, each separated by three rows of interwhorls; in ventral view these rows reduce to two; the interwhorls are not complete ventrally.

Color pattern in life: except for the following characteristics, coloration is similar in life and preservative. According to the color catalogue of Köhler (2012), head is smoke gray (#267) except for frontoparietals, which are grayish olive (#273). Background color medium sulphur yellow (#94) with dorsal and dorsolateral grayish olive spots (#275). Tubercles of paravertebral rows chamois (#84). Anterior limbs medium sulphur yellow (#94); posterior limbs cream white (#52) laterally. Tail light sky blue (#191) (Fig. 5).

Color pattern in preservative: dorsal surface of the head, from rostral to interparietal scales, smoke grey (#267), and glaucous (#272) at the level of the temporals and occipitals. Grayish olive (#274) irregular stripe between nostrils and eye extending along loreals and continuing through eye and along the canthus temporalis. Supralabials and infralabials smoky white (#261) with central grayish olive spots (#274). Body, tail and limbs pale cinnamon (#55) background color with smoke gray spots (#266), intercalated by dark grayish olive spots (#275) along the dorsal and dorsolateral surface (Fig. 4A). Pearl gray spots (#262) along vertebral rows; tubercles of paravertebral rows chamois (#84). Ventral surface of the body pale sulphur yellow (#92) (Fig. 4B).

Variation: variation in morphometrics and scalation of the individuals is shown in Tables 2 and 3. Among individuals, coloration varies from lighter to darker hues, both in live and preservative.

Distribution and habitat: Lepidophyma lusca sp. nov. is currently known only from the type locality between 194–220 m elevation (Ahumada-Carrillo 2013) (Fig. 6). This site is located in the physiographic region of the Sierra Madre Oriental, specifically belonging to the Carso Huasteco province (Lemos-Espinal et al. 2018). The area is characterized by outcrops of Cretaceous limestones with thinner interbeds of shales (Raines 1968). Vegetation corresponds to tropical semi-evergreen forest (INEGI 2017). The upper arboreal stratus is dominated by Bursera simaruba, Tabebuia sp., Inga sp., Croton draco, Vachellia aff. cornigera, Aphananthe monoica, Annona sp., Lonchocarpus sp., and Ficus spp. There is also a distinct lower height stratus comprised by Parmentiera aculeata, Bixa orellana, Bocconia arborea, Bauhinia divaricata, Cupania dentata, Pseudobombax ellipticum, and Urera sp. On the banks of the river is frequent to find Platanus mexicana. Climate at the locality is semi-warm humid with abundant rainfall, a mean temperature of 23.9 °C, minimum and maximum temperature of 11.6 °C and 34.4 °C, respectively, and mean annual precipitation of 1750 mm (Fick & Hijmans 2017; INEGI 2009). This species is restricted to the stream’s banks, where it is found in crevices of limestone covered by the canopy (Fig. 7).

Natural and life history: fecal analysis of individuals collected shows that L. lusca sp. nov. is insectivorous like other night lizard species (Bezy & Camarillo 2002). As for other members in the genus, the reproductive mode of this species is viviparous. Mating season is unknown, but probably occurs at the end of the rainy season, like other Lepidophyma species (Méndez de la Cruz et al. 1999). Five females gave birth in captivity a total of 16 neonates between 2 nd to 13 th June of 2019. The minimum SVL of pregnant females was 45 mm. The mean litter size was 3.2 ± 1.48 neonates (range: 1–5). Neonates had a mean SVL of 22.6 ± 0.88 mm (range: 21–24 mm) and a mean mass of 0.22 ± 0.02 g (range: 0.17–0.27 g). The mean relative litter mass (RLM), according to the method described by Rodríguez-Romero et al. (2005; RLM = litter mass/mass of female after parturition), was 0.3940 ± 0.1549 g (range: 0.1541 –0.4405 g). Despite the currently restricted distribution of this species, the population seems to be very abundant; approximately more than 30 individuals were observed per day of sampling.

Activity and behavior: Lepidophyma lusca sp. nov. is rarely seen outside crevices, only exposing its head and part of its body when active. The activity period of L. lusca sp. nov. was diurnal-crepuscular (08:00–20:00 h), although lizards were more active during the twilight (19:15–20:15 h), with cessation of activity at the first hours of the night, when the congeneric L. occulor Taylor 1939, which occurs in syntopy with L. lusca sp. nov., started its activity. Preliminary field observations made by one of the coauthors (FJMN) in the winter of 2018 suggest that this activity pattern might be constant throughout the year.

Thermal and hydric physiology: the mean microhabitat T e during the day was 28.8 ± 1.37 °C, with a minimum and maximum temperature range of 26.7 to 32.4 °C, respectively. At night, the mean value of T e was 27.6 ± 0.58 °C, ranging from 26.5 to 29.1 °C. The period of higher activity of L. lusca sp. nov. was around twilight, when T e ranged from 27.6 °C to 29.6 °C. Mean T b (30.1 °C) was higher than mean T set (26.8 °C). CT max of the species was just 3 °C above than the maximum recorded T e during the day, while CT min was 10 °C below the minimum recorded value of T e. Lepidophyma lusca sp. nov. had high rates of evaporative water loss, accounting for more than 1% of its body mass per hour in the dry air desiccation system (Table 4).