New records of Gerrhonotus parvus Knight & Scudday , 1985 ( Squamata , Anguidae ) in the state of Coahuila , México

We document the first records of Gerrhonotus parvus in the state of Coahuila, México. From March 2012 to March 2017, 6 males and 2 females were found in pine forest and submontane scrubland plant communities in the Sierra de Zapalinamé Natural Protected Area, which is located in the municipalities of Saltillo and Arteaga. These records extend the known distribution of the species 28–44 km west of the nearest occurrences in the state of Nuevo León.


Introduction
The genus Gerrhonotus Wiegmann, 1828 is endemic to North America and represented by 7 species: G. farri Bryson & Graham, 2010, G. infernalis Baird, 1859(1858), G. liocephalus Wiegmann, 1828, G. lazcanoi Banda-Leal, Nevarez de los Reyes & Bryson, 2017, G. lugoi McCoy, 1970, G. ophiurus Cope, 1866, and G. parvus (Knight & Scudday, 1985).The distribution of the group is complex; the large species have wide ranges, and the small species are range-restricted (Fig. 1).The most widely distributed species are G. liocephalus in western and southern México and G. infernalis in central and northern México and southern Texas (Good 1994).The remaining 5 species have restricted distributions, known from small areas and only a few individuals.Gerrhonotus ophiurus is distributed in central and southwestern San Luis Potosí, eastern Querétaro, Hidalgo, Tlaxcala, Puebla, and mountainous areas of northern Veracruz (Lemos-Espinal and Dixon 2013).Gerrhonotus lugoi occurs in the Cuatrociénegas basin, Coahuila (McCoy 1970) and the municipality of Mina, Nuevo León (García-Vázquez et al. 2016).Gerrhonotus farri is found near the town of Tula, Tamaulipas (Bryson and Graham 2010).Gerrhonotus parvus is known only from the state of Nuevo León, in the municipalities of Galeana, Los Rayones, Santa Catarina, andSantiago (Banda-Leal et al. 2013, Banda-Leal et al. 2014b).The most recently described species in the genus, G. lazcanoi, has only been found at 1 site near the Coahuila/Nuevo León border in the municipality of García, Nuevo León.
Relatively little is known about the biology of the last 4 species, G. lugoi, G. farri, G. parvus and G. lazcanoi.For G. lugoi, there is a report of reproduction in captivity, courtship, and litter size (Lazcano et al. 1993).For G. parvus, there is more detailed information about its natural history (Bryson et al. 2003), as well as its distribution, litter size, sympatric herpetofauna, and potential predators (Banda-Leal et al. 2013, 2014a, b, Banda-Leal 2016).Gerrhonotus farri and G. lazcanoi are known from a single specimen each (Bryson andGraham 2010, Banda-Leal et al. 2017).
Although known from several localities in Nuevo León, G. parvus remains an enigmatic species.It is a small lizard with a maximum total length (TL) of 130 mm for males (Banda-Leal et al. 2005) and 84.5 mm for females (Knight and Scudday 1985).This species differs from its congeners by a combination of morphological characters, including small adult size, smooth dorsal scales, nasals in contact with medial fifth supraocular, suboculars separated from lower primary temporal by an upper lip, and wide pale crossbands on the tail (Knight and Scudday 1985).Gerrhonotus parvus is known from the Sierra Madre Oriental in the state of Nuevo León (Fig. 2).The species was originally reported for the municipality of Galeana in a transition zone between pine forest (Pinus arizonica) and open gypsophyllous scrub at 1650 m above sea level.(Knight and Scudday 1985), and subsequently reported to the northwest from the type locality, in the municipality of Santiago in Cañón de San Isidro (Banda-Leal et al. 2002).This canyon is at 1600 m above sea level, runs east and west, and is characterized by steep limestone walls covered with Agave (Agave lechuguilla, A. bracteosa), sotols (Dasylirion sp.), and scrub oaks (Quercus sp.), and has intermittent pools of water.The canyon bottom has piles of leaf litter with scattered large rocks (Banda-Leal et al. 2002, Bryson andLazcano 2005).Between the Galeana and Cañón de San Isidro sites, 1 specimen of G. parvus was found in the Cañón de Mireles in the municipality of Los Rayones, with a habitat similar to that of the Cañón de San Isidro, but at 900 m above sea level, the lowest record for this species (Conroy et al. 2005).Later, 1 specimen was found in the municipality of Santa Catarina, in Cañón de Reflexiones, northwest of the Cañón de San Isidro, both with very similar habitats (Banda-Leal et al. 2014b).
We surveyed a mountainous region in eastern Coahuila called the Sierra de Zapalinamé (Fig. 2).It is located to the south of Saltillo, Coahuila and was decreed as a natural protected area (ANP) in 1996 (DOF 1996).More than 40% of the water that supplies the city of Saltillo comes from underground aquifers (Marines-Gómez 2012), and its conservation is therefore essential for the city.The Sierra de Zapalinamé is near the city of Saltillo-Arteaga and serves as a refuge for biodiversity.With the help of the ANP personnel, we documented 8 specimens of G. parvus from the study region (Fig. 3).Here we provide results of our discoveries.

Methods
From June 2016 to August 2017, we visited each month the Sierra de Zapalinamé which presents a complex topography, composed of valleys, canyons, hills, and steep slopes ranging from the 1,700 to 3,100 m above sea level.Its vegetation types range from desert scrub, submontane grasslands, gallery oak, and pine forests.Canón de San Lorenzo is where most of the G. parvus were found, and it is one of the most diverse floral communities in the Sierra Madre Oriental.The following species are dominant: Sotols (Dasylirion cedrosanum), Chaparro Oak (Quercus pringlei), Little Bird Tree (Lindleya mespiloides), Evergreen Sumac (Rhus virens), and Alderleaf Mountain Mahogany (Cercocarpus montanus), with a rocky substrate with abundant crevices.In the Paraje Aguajes area, the principal vegetation is composed mainly of Chaparro Oak, Mexican Drooping Juniper (Juniperus flaccid), Sotols, Lechuguilla Agave (Agave lechuguilla), Apark Palm (Brahea dulcis).In the Cerro de las Nieves II, the main plant elements are Sotols, Chaparro Oak, Little Bird Tree, and various species of grasses.
We searched for lizards in suitable habitat by means of active searching method.The specimens of G. parvus that were collected were deposited in the preserved herpetological collection of the Facultad de Ciencias Biológicas of the Universidad Autónoma de Nuevo León as catalog numbers UANL.We measured snout-vent length (SVL) and tail length (T a L) (Vernier Helios, accuracy 0.05 mm), as well as body and environmental temperatures (RayTek ST30 Pro Enhanced), and the geopositioning (Garmin eTrex 20).Specimens were collected with permission of SEMARNAT (Secretaría del Medio Ambiente y Recursos Naturales y Cambio Climático), under the permit NUM/ SGPA/DGVS/08377/16 to David Lazcano.Prior to our study, staff members of Sierra de Zapalinamé found and photographed 2 individuals of G. parvus.Identification.We examined all the collected and photographed material; and compared external morphology using the scale criteria for anguids (Good 1988), as well as the description of the species (Knight and Scudday 1985).In addition, the identification of specimens was confirmed by Robert W. Bryson Jr.

Discussion
Here we present the first records of G. parvus for the state of Coahuila, as well as for the western portion of the Sierra Madre Oriental.These records represent a total of 8 specimens found, of which 2 were collected alive, 2 that were collected as burned in a fire, and 4 observed alive in the field; with all of the specimens photographed.The 4 specimens collected in Coahuila added to the 12 of Nuevo León mentioned in the literature, bringing the total to 16 specimens in scientific collections (Table 1).Gerrhonotus parvus is currently protected by national and international laws, is under special protection status by the (NOM-059-SEMARNAT 2010), and is also listed in the IUCN (2013) as Endangered under criteria B1ab(iii) The ecological characteristics of the areas in Coahuila are similar to those in Nuevo León, but the specimens are found at higher elevations.The area known as Cerro de las Nieves II in on the side of the highway Saltillo-Matehuala is similar to the area of Galeana, but with greater vegetation cover, while Cañón de Calabacillas and San Lorenzo resemble more the area of Cañón de Reflexiones in Santa Catarina.The area of Paraje Aguajes is very similar to the Cañón de San Isidro.

Figure 1 .
Figure 1.Map showing the known occurrence of genus Gerrhonotus.Polygons indicate wide distribution species.The yellows correspond to G. infernalis, red to G. ophiurus, orange to G. liocephalus and blues to G. cf.liocephalus.The symbols indicate local distribution species.Reddish pentagon corresponds to G. lugoi, red triangule to G. lazcanoi, green circle to G. parvus and blue diamond represents G. farri.

Figure 2 .
Figure 2. Distribution map of Gerrhonotus parvus.The white circles represent the known occurrence in Nuevo León.The black stars indicate the new localities where the specimens of G. parvus were found in the Sierra de Zapalinamé, Arteaga and Saltillo municipalities, Coahuila, México.

Figure 3 .
Figure 3. New records of G. parvus in the Sierra de Zapalinamé, Saltillo and Arteaga, Coahuila.The symbols indicate collecting sites.The white star correspond to Visiting Attention Center, the white box to La Explanada, the red circle to fire area, the black circle to Paraje Aguajes, black star to Cañón de Calabacillas, and white circle to slope off the road Saltillo-Matehuala.

Table 1 .
Reports of Gerrhonotus parvus obtained in this study and the literature.SRSU: Sul Ross State University.UANL: Universidad Autónoma de Nuevo León.