Amphibians and Reptiles of the state of Nuevo León, Mexico

Abstract We compiled a check list of the herpetofauna of Nuevo León. We documented 132 species (23 amphibians, 109 reptiles), representing 30 families (11 amphibians, 19 reptiles) and 73 genera (17 amphibians, 56 reptiles). Only two species are endemic to Nuevo León. Nuevo León contains a relatively high richness of lizards in the genus Sceloporus. Overlap in the herpetofauna of Nuevo León and states it borders is fairly extensive. Of 130 native species, 102 are considered species of Least Concern in the IUCN red list, four are listed as Vulnerable, five are listed as Near Threatened, and four are listed as Endangered. According to SEMARNAT, 78 species are not of conservation concern, 25 are subject to Special Protection, 27 are Threatened, and none are listed as in Danger of Extinction. Given current threats to the herpetofauna, additional efforts to understand the ecology and status of populations in Nuevo León are needed.


Introduction
The flora and fauna of Nuevo León is very species rich. Broadly speaking, it consists mainly of a group of species characteristic of the great deserts of North America, as well as species from the temperate forests of the Sierra Madre Oriental and subtropical species that extend their distribution northward, in some cases even from Central or South America, through the lowlands of the Atlantic slope. Despite these characteristics, there have been few studies on the diversity and distribution of the species of amphibians and reptiles in the state and those that have been conducted have focused almost entirely on the forests of the Sierra Madre Oriental and satellite mountains to the north and northeast of the city of Monterrey (Valdez-Tamez et al. 2003, 2009a, Contreras-Lozano et al. 2007, Lemos-Espinal and Cruz 2015. The vast plains to the east of the Sierra Madre Oriental as well as the portion of the Mexican Plateau in the southwestern corner of the state remain relatively unstudied. Currently there is no systematic program to study the state's herpetofauna across different regions. Consequently, one of the main threats to the conservation of the diversity of amphibians and reptiles of the state is a lack of knowledge. Coupling this lack of knowledge of the herpetofauna of the state with problems associated with the high demand for water, energy, and food to meet the increasing needs of one of the largest and fastest growing cities in Mexico (Monterrey) does not suggest an encouraging outlook for the future of the herpetofauna of Nuevo León. To help increase the awareness of the herpetofaunal richness of Nuevo Léon, we gathered information on the presence of amphibian and reptile species. In addition, given the potential for increased impacts of humans on the environment, we also gathered information on the conservation status of these species. Our goal is to provide a readily accessible compilation of the herpetofaunal species and their conservation status, and to expand upon previous statewide checklists (e.g., Lemos-Espinal and Cruz 2015).

Study site
The State of Nuevo León is found in northeastern Mexico (98°26' to 101°14'W, 23°11' to 27°49'N). It shares its borders with the U.S. state of Texas and the Mexican states of Coahuila, Tamaulipas, San Luis Potosí, and Zacatecas (Fig. 1). The area of the state is 64,220 km 2 , with an elevational range of 50 to > 3,710 m above sea level (INEGI 2010). The capital, Monterrey, forms a large metropolitan area that contains approximately 88% of the population of Nuevo León, with more than four million inhabitants (INEGI 2010). Nuevo León has an extensive road network that runs throughout most of the state (INEGI 2010).
Three topographical regions can be identified in Nuevo León ( Fig. 1; see also Lemos-Espinal and Cruz 2015 for more details). The first region (area = 23,138 km 2 ; 36% of the state's surface) is a relatively flat area with a series of small, low, scattered hills (50 to 250 m above sea level) that occurs in the central, eastern, northern, and northwestern parts of the state (Alanís-Flores et al. 1996). This region includes areas that are part of the Great Plains of North America.
The second region is the Sierra Madre Oriental, located mainly in the western portion of Nuevo León (Alanís-Flores et al. 1996). The Sierra Madre Oriental divides the low-elevation plains of the central, eastern, and northwestern parts of the state from the Mexican Plateau in the southwestern corner of the state. The Sierra Madre Oriental consists of mountain ranges that average 2000 m above sea level; with their elevation generally decreasing from south to north. The Sierra Madre Oriental is the wettest region. Near Monterrey the Sierra Madre Oriental is interrupted by valleys that create an archipelago of mountain islands (elevation not exceeding 1550 m above sea level) in the midst of arid and semiarid valleys.
The Mexican Plateau is the third region in Nuevo León, and is found in the southwestern corner of the state (Alanís-Flores et al. 1996). The altitude varies between 1500 and 2000 m, and in general is a flat and arid-semiarid area (Alanís-Flores et al. 1996, Velazco-Macías et al. 2008, Velazco-Macías 2009, INEGI 2010, Lemos-Espinal and Cruz 2015. For most of Nuevo León, the climate is very hot, with precipitation generally not exceeding 500 mm annually (Alanís-Flores et al. 1996). Rains occur in the summer or infrequently throughout the year. The Mexican Plateau in the southwestern part of the state is also hot and very dry with annual rainfall < 200 mm. A temperate sub-humid climate is found in the Sierra Madre Oriental (Alanís-Flores et al. 1996). Here the temperature is milder (18°C-20°C) and average annual precipitation ranges from 600 to 900 mm. At high elevations (> 3000 m), alpine and subalpine climates are found. The Coastal Plain of the Gulf in the central part of the state includes tropical, sub-hot, and subhumid climates,receiving an intermediate amount of precipitation (Alanís-Flores et al. 1996).
Six vegetation types are found in Nuevo León: Chihuahuan Desert Scrub; Tamaulipan Thorn Scrub; Submontane Scrub; Montane Forest; Grassland; and Ri- parian, Subaquatic, and Aquatic Vegetation, as well as 11 plant communities corresponding to three floristic provinces: the Mexican Plateau, the Coastal Plain of the Northeast, and the Sierra Madre Oriental (Rzedowski 1978).

Data collection
We obtained the list of amphibians and reptiles of the state of Nuevo León from the following sources: (1) specimens in the collections of the Laboratorio de Ecología-UBIPRO (LEUBIPRO); (2) databases from the Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (National Commission for the Understanding and Use of Biodiversity; CONABIO), that were the results of various scientific projects undertaken by this institution in Nuevo Léon and also includes records from the following 28 collections: Colección de Vertebrados, Instituto de Investigaciones de Zonas Desérticas, Universidad Autónoma de San Luis Potosí (IIZD); Colección de Vertebrados, Universidad Autónoma de Baja California (CMMEX); Colección Herpetológica Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León (UANL); Colección Herpetológica, Departamento de Zoología, Escuela Nacional de Ciencias Biológicas (ENCB); Colección Herpetológica, Museo de Zoología "Alfonso L. Herrera", (3) a thorough examination of the available literature on amphibians and reptiles in the state such as: Liner (1964Liner ( , 1966aLiner ( ,b, 1991aLiner ( ,b, 1992aLiner ( ,b, 1993Liner ( , 1994aLiner ( ,b, 1996a, Liner and Chaney (1986, 1987, 1990a,b, 1995a, Dixon (1992, 1994), , , Rabb (1956), among others; and (4) our personal field work, primarily focused around the extreme western part of the state on the state line between Coahuila and Nuevo León. We visited this region periodically from 2002 to 2014, taking notes on the amphibians and reptiles observed during visual encounter surveys. Taxonomy and Standard English names used here are those found in . Each species was assigned to one of three floristic provinces present in Nuevo León: the Mexican Plateau, the Coastal Plain of the Northeast, and the Sierra Madre Oriental (Rzedowski 1978).
Species were included in the check list only if we were able to confirm the record, either by direct observation or through documented museum records or vouchers in the state. Species with a questionable distribution in Nuevo León, or those that are mentioned in the literature without documented support of their presence in the state were not included in our list. In addition, we recorded the conservation status of each species based on three sources: 1) the IUCN Red List 2014; 2) Environmental Viability Scores from Wilson et al. (2013a,b); 3) listing in SEMARNAT (2010)

Results
The herpetofauna of Nuevo León includes a total of 132 species: 23 amphibians (three salamanders, 20 anurans) and 109 reptiles (six turtles, 42 lizards, 61 snakes) (Table 1; see also Lemos-Espinal and Cruz 2015). These represent 30 families: 11 of amphibians (two of salamanders and nine of frogs), and 19 of reptiles (four of turtles, eight of lizards and seven of snakes), and 73 genera: 17 of amphibians (three of salamanders and 14 of frogs), and 56 of reptiles (five of turtles, 14 of lizards and 37 of snakes) (Table 1).
Of the 132 species we documented, two are not native to Nuevo León: the Mediterranean House Gecko (Hemidactylus turcicus; see Rödder and Lötters 2009), and the Brahminy Blindsnake (Indotyphlops braminus; see Servoss et al. 2013 Five of these species have a narrow distribution in southeastern -eastern Coahuila and adjacent Nuevo León (C. priscus, P. galeanae, S. oberon, T. exsul), and even Tamaulipas (P. dicei). One more is limited to Nuevo León and adjacent Tamaulipas (S. chaneyi), and another 10 range from Nuevo León and Tamaulipas southward to southern Veracruz and northern Oaxaca, mainly on the Atlantic slopes of the Sierra Madre Oriental (E. longipes, E. miotympanum, S. minor, S. parvus, S. silvicola, L. sylvaticum, S. hidalgoensis, Table 1. Checklist of amphibians and reptiles of Nuevo León. We also provide the Habitat type (CD = Chihuahuan Desert, SM = Sierra Madre Oriental, TS = Tamaulipan Thornscrub), IUCN Status (DD = Data Deficient; LC = Least Concern, V = Vulnerable, NT = Neat Threatened; E = Endangered; CE = Critically Endangered), and Environmental Vulnerability Score (EVS; the higher the score the greater the vulnerability) from Wilson et al. (2013a,b), and conservation status in Mexico according to SEMARNAT (2010) (P = in danger of extinction, A = threatened; Pr = subject to special protection, NL -not listed). Source denotes whether the species was observed in the field by the authors (A), documented in the CONABIO data base and/or museum collections (C/M), or found in the literature (citation of source). Four additional species (Kinosternon integrum, Sceloporus spinosus, S. torquatus, and Trimorphodon tau) are widely distributed from central Mexico through the Mexican Plateau, and in some cases (T. tau) on both coasts. One species has disjunct populations in the highlands of Mexico (Thamnophis pulchrilatus), and another is limited to the Chihuahuan Desert of Mexico (Holbrookia approximans). The other two species endemic to Mexico (Barisia imbricata and Phrynosoma orbiculare), occur on the Sierra Madre Occidental and the Sierra Madre Oriental; one of them, P. orbiculare, ranges even into the mountains of the Transvolcanic Belt of the central part of the country.

Habitat
Of the 130 native species of amphibians and reptiles in Nuevo León, 102 are considered species of Least Concern in the IUCN red list (18 amphibians, 84 reptiles), four species (1 amphibian, 3 reptiles) are listed as Vulnerable, five species (2 amphibians, 3 reptiles) are listed as Near Threatened, and four species (0 amphibians, 4 reptiles) are listed as Endangered (IUCN, 2015). Also, according to SEMARNAT listing (SEMAR-NAT 2010), 78 species are not listed (i.e., not of conservation concern; 17 amphibians, 61 reptiles), 25 species are Subject to Special Protection (5 amphibians, 20 reptiles), 27 species are Threatened (1 amphibian, 26 reptiles), and no species are listed as in Danger of Extinction. Several taxa are also at risk according to the EVS values. In particular, plethodontid salamanders, turtles in the families Emydidae and Testudinae, and anguid lizards have high EVS values, suggesting they may be of particular concern.   Table 1 for abbreviations; in some cases species have not been assigned a status by the IUCN and therefore these might not add up to the total number of species in a taxon). Mean EVS is the mean Environmental Vulnerability Score, scores ≥ 14 are considered high vulnerability (Wilson et al. 2013a,b) and conservation status in Mexico according to SEMARNAT (2010) in the Order NL, Pr, A, P (see Table 1 for abbreviations).  The state with the least overlap is Texas (overall 65.4%, amphibians 82.6%, reptiles 61.7%), which might be expected since the extent of the border is relatively small and they are separated by the Río Grande. In an analysis of the herpetofauna of the Mexican and United States Border States, including Nuevo León, Smith and Lemos-Espinal (2015) found significant similarities or clustering among Texas, Tamaulipas, Nuevo León, and Coahuila for the entire herpetofauna, with subsets of the herpetofauna (e.g., amphibians, reptiles, anurans, and lizards) showing slightly different clustering patterns; although Nuevo León frequently clustered with Tamaulipas and Coahuila. The particular similarity among Nuevo León, Tamaulipas, and Coahuila likely reflects similarities in the biotic provinces found in those states (Smith and Lemos-Espinal 2015).

Class
The conservation status of the herpetofauna of Nuevo León has relatively fewer species listed in the IUCN red list and SEMARNAT compared to other states, at least as far as listings based on IUCN red list and SEMARNAT, as well as the EVS values provided in Wilson et al. (2013a, b). This is not to say that the herpetofauna of Nuevo León should be considered safe. Given the expanding population of Monterrey, and the potential consequences of such expansion on natural resources in the state, we must be vigilant to the threats to the herpetofauna of Nuevo León. In addition, the relative paucity of ecological studies on the amphibians and reptiles in Nuevo León mean much of our understanding of these species' status in Nuevo León is based upon information obtained in other states. We hope our summary of the species of amphibians and reptiles from Nuevo León, and their putative conservation status, will prompt further research on the ecology and status of these species in Nuevo León. Such baseline information is critical to evaluating and monitoring any changes in populations in Nuevo León that can arise due to urbanization around Monterrey and potential climate change and other threats in this area (see Biggs et al. 2010, Seager and Vecchi 2010.