Acevedo et al. (2016) used two mitochondrial genes and 23 morphometric landmarks to evaluate the taxonomic status of Rhinella marina. They demonstrated that there were two separate evolutionary lineages within R. marina represented by two distinct morphotypes, one eastern and one western Andean. The concordance between the observed geographic patterns in morphometric and genetic traits support the recognition of two distinct species. The eastern populations retained the name R. marina, and the name R. horribilis was revalidated for the western populations.

Duellman et al. (2016) treated two major clades as genera (Hyla, restricted to the Old World, and Dryophytes distributed primarily in the New World but with three species in Asia). Dryophytes is therefore used here. In addition, Sarcohyla bistincta was originally placed in the genus Hyla by Cope (1877), but was moved to the genus Plectrohyla by Faivovich et al. (2005). Duellman et al. (2016) performed a phylogenetic analysis of sequences from 503 species of hylid frogs and four outgroup taxa that resulted in a new phylogenetic tree of treefrogs. Among other results, a conservative new classification based on this tree has five new generic names, including Sarcohyla. This new genus contains 24 species, most of them from the Hyla bistincta and Hyla arborescandens groups of Duellman (2001), and includes the new combination Sarcohyla bistincta.

The six species of ranid frogs that occur in Durango were long considered to be in the genus Rana, however, Frost et al. (2006) recommended the use of the name Lithobates, which was controversial. More recently, Yuan et al. (2016) retained all the species of these genera in the traditional genus Rana, based on a phylogenetic analysis of six nuclear and three mitochondrial loci sampled from most species of Rana, the lack of any diagnostic morphological characters for the genera recognized by Frost et al. (2006), and the clear monophyly of a larger group that include these genera. Rana is used here following Yuan et al. (2016) and AmphibiaWeb (2017).

Montanucci (2015) studied the comparative morphology and color pattern variation of short-horned lizards (Phrynosoma douglasii species complex) using multivariate analyses of 20 morphological and color-pattern characters, and univariate statistics were summarized for 52 samples. The results of the morphological data analyses supported the recognition of P. douglasii as a distinct species, and the resurrection of P. brevirostris and P. ornatissimum as species distinct from P. hernandesi. He recognized two subspecies of P. ornatissimum: P. o. ornatissimum from central and southern New Mexico and western Texas; and P. o. brachycercum from the lower eastern slopes of the Sierra Madre Occidental and the adjacent plains in the Mexican states of Chihuahua, Durango, and Zacatecas.

Tucker et al. (2016), based on Steyskal (1971), explained and justified why the genus name Aspidoscelis should be treated as masculine. Names used for species of Aspidoscelis occurring in Durango are thus A. costatus, A. gularis, A. inornatus, and A. marmoratus.

Card et al. (2016) analyzed the genetic structure and phylogenetic relationships of Boa populations using mitochondrial sequences and genome wide SNP data obtained from RADseq, finding evidence that supports three widely-distributed clades roughly corresponding with western North America (Pacific Coast of Mexico), eastern North America (Atlantic Coast of Mexico and Central America), and South America. One of those clades represented the populations of the Pacific slopes of Mexico, from northern Sonora to west of the Isthmus of Tehuantepec. They resurrected the name sigma from the population described by Smith (1943) as Constrictor (= Boa) constrictor sigma from the María Madre Island, Tres Marías Islands, Nayarit, Mexico, which was regarded as a junior synonym of B. c. imperator by Zweifel (1960). Card et al. (2016) recognized the Boa populations from the slopes of the Mexican Pacific as Boa sigma, and this is followed here.

Twenty-one of the 36 species of Amphibians that inhabit Durango are endemic to Mexico, 13 of them are limited to the Sierra Madre Occidental or to the Pacific Coast and the lowlands of the Sierra Madre Occidental (Table 1). Three more are species typical of the Mexican Plateau (Table 1). Another five have wide distributions that include parts of both Sierras Madre (Occidental and Oriental) and part of the Mexican Plateau (Table 1).

Of the 15 amphibian species of Durango that are not endemic to Mexico, one is an introduced species (Rana catesbeiana), and eleven more are found in the USA and Mexico (Table 1). The remaining three species have a wide distribution from southern USA to Central or South America (Table 1).

Twenty-four of the 54 species of lizards that occur in the state are endemic to Mexico, one of them to the state of Durango (Xantusia bolsonae), three more have narrow distributions in northeastern Durango: Sceloporus maculosus limited to the Río Nazas drainage in Durango and Coahuila; Uma paraphygas limited to the Bolsón de Mapimí of southeastern Chihuahua, southwestern Coahuila, and northeastern Durango; and Xantusia extorris limited to northeastern Durango and adjacent Coahuila. Two more are restricted to small areas in the Sierra Madre Occidental: Sceloporus lemosespinali to eastern Sonora, northern Chihuahua, and extreme northwestern Durango; and S. shannonorum in central Durango to extreme northern Jalisco. Another ten species that occur in Durango and are endemic to Mexico are typical to the Pacific Coast and/or the Sierra Madre Occidental: Anolis nebulosus, Coleonyx fasciatus, Ctenosaura pectinata, Sceloporus albiventris, S. bulleri, S. heterolepis, S. nelsoni, Urosaurus bicarinatus, Plestiodon bilineatus, and Aspidoscelis costatus. One more is a species typical of the Chihuahuan Desert: Holbrookia approximans. Another species is typical of the Sierra Madre Oriental, with an isolated population occurring in southern Durango: Plestiodon lynxe. One more occurs in southern Mexico in the state of Puebla, Hidalgo, Oaxaca, and Chiapas, with isolated populations in Aguascalientes, Jalisco, and southwestern Durango: Gerrhonotus liocephalus. The remaining five lizard species endemic to Mexico have a wide distribution occurring in both Sierras Madres (Occidental and Oriental): Barisia ciliaris, and even in the Transvolcanic Belt of central Mexico (Phrynosoma orbiculare), or are species typical of the Mexican Plateau: Sceloporus scalaris, S. spinosus, and S. torquatus.

The remaining 30 species of lizards that inhabit Durango are not endemic to Mexico. Twenty-six of the non-endemics are species found in the USA and Mexico (Table 1). Three are found from northern Mexico to Central America (Table 1). The last one, Hemidactylus turcicus, is introduced to Durango.

Twenty-four of the 61 species of snakes that occur in Durango are endemic to Mexico. Two of them to Durango: Adelophis foxi and Thamnophis nigronuchalis. Four others have a narrow distribution in the Sierra Madre Occidental: Lampropeltis webbi (Pacific slope of the Sierra Madre Occidental near the Durango – Sinaloa border); Thamnophis errans (from central Chihuahua, Durango and adjacent Zacatecas); Thamnophis unilabialis (eastern Sonora and western Chihuahua to northern Durango); and Crotalus stejnegeri (western Durango and adjacent southern Sinaloa). Eight more are typical species of the Pacific slopes of the Sierra Madre Occidental: Boa sigma, Leptophis diplotropis, Mastigodryas cliftoni, Pseudoficimia frontalis, Geophis dugesii, Hypsiglena torquata, Leptodeira splendida, and Thamnophis validus. Another nine of the endemic snakes have a wide distribution in central Mexico that include the Mexican Plateau and/or the Transvolcanic Belt of central Mexico and the Sierra Madre Occidental and in some cases even the Sierra Madre Oriental: Conopsis nasus, Lampropeltis mexicana, Pituophis deppei, Salvadora bairdi, Tantilla bocourti, Trimorphodon tau, Rhadinaea laureata, Storeria storerioides, and Thamnophis melanogaster. The remaining endemic species, Thamnophis pulchrilatus, has a spotty distribution in highlands of the Sierra Madre Occidental and the Sierra Madre Oriental.

Thirty snake species that are found in Durango are distributed from the USA to Mexico (Table 1). Five more species are found from central or southern USA to Central or South America (Table 1). One species ranges from Mexico to northeastern South America: Masticophis mentovarius. The last species that inhabits Durango and is not endemic to Mexico is an introduced species to Mexico, Indotyphlops braminus.

Three of the five species of turtles that inhabit Durango are endemic to Mexico, two to the Bolsón de Mapimí in southeastern Chihuahua, southwestern Coahuila, and northeastern Durango: Kinosternon durangoense and Gopherus flavomarginatus. The other is widely distributed in the lowlands of western Mexico and throughout the central and southern portion of the Mexican Plateau: Kinosternon integrum (it is not native to the Valley of Mexico but has been introduced there). The two non-endemic species of turtles are found from southwestern USA to northern Mexico: Trachemys gaigeae and Kinosternon hirtipes.

The Sierra habitat type (46.1%) and the arid-semiarid habitat type (42.8%) had the highest percentages of the herpetofauna in Durango, whereas both the valley (29.9%) and Quebradas (24.0%) habitat types had a lower percentage (Table 3). For amphibians alone, the Sierra habitat type had slightly more than 50% of the species in Durango (52.8%) followed by the valley habitat type (41.7%) and Quebradas habitat type (30.6%). As might be expected, the arid-semi-arid habitat type had the fewest amphibian species (19.4%; Table 3). This distribution of species is also found when examining anuran species (Table 3). For salamanders, species are almost exclusively found in the Sierra habitat type, with one species found in the valley habitat type, and none in the arid-semi-arid and Quebradas habitat types (Table 3). Reptiles showed a different pattern, with the most species being found in the arid-semiarid habitat type (50%) and the Sierra habitat type (44.1%), with the valleys (26.3%) and the Quebradas (22.0%) having fewer species. This pattern is found in both lizards and snakes (Table 3), and is primarily driven by the most diverse families in these groups (e.g., Phrynosomatidae, Colubridae, and Natricidae). Turtles are found in the four habitat types with 80% of the species occurring in the arid-semiarid habitat type and less than half of the species found in the other three habitat types.

Overall, Durango shares the most species with Chihuahua (Table 4). This holds true for amphibians; however, Durango shares almost as many species of amphibians with Sinaloa and Nayarit as with Chihuahua. For reptiles, Durango and Chihuahua share the most species by a large margin over the other states (Table 4). The cluster analysis recovered the same tree structure for Durango and its neighboring states when the entire herpetofauna, reptiles, and amphibians are each considered (Figure 5). In each case, Durango and Chihuahua made a cluster and Nayarit and Sinaloa made another cluster. In addition, Coahuila formed a cluster with the Durango-Chihuahua pairing. Such a pattern likely reflects the fact that Durango, Chihuahua, and Coahuila all have extensive tracts of Chihuahuan Desert habitats. Similarities and differences in species among Durango and its neighboring states likely is the result of the habitats and vegetation types found in each state (see also Smith and Lemos-Espinal 2015, Lemos-Espinal and Smith 2016, Lemos-Espinal et al. 2017). Such results suggest that the conservation of the herpetofauna of this region will need habitat specific conservation plans that cross state borders and will require integration of state, regional, and country-level efforts.

Figure 5. 

Results of cluster analysis of the herpetofaunas of Durango and its neighboring states (Chihuahua, Coahuila, Nayarit, and Sinaloa). The distances provided are Euclidean distances for the entire herpetofauna, reptiles only, and amphibians only, respectively.

Overall, 7.6% of the amphibian and reptile species were IUCN listed (i.e., Vulnerable, Near Threatened, Endangered, or Critically Endangered), but 33.3% were placed in a protected category by SEMARNAT and 29.3% categorized at high risk by the EVS (Tables 1, 2). For amphibians, 12.1% were IUCN listed, 31.4% protected by SEMARNAT, and 20% at high risk according to the EVS (Tables 1, 2). For reptiles, 6.1% were listed in IUCN, 33.9% protected by SEMARNAT, and 32.2% at high risk by EVS. These results suggest that the herpetofauna of Durango is considered to be of relatively low conservation concern at a global scale, but at a national level, there is much greater conservation concern. There are several taxa that, based on their IUCN listing, SEMARNAT category, or their EVS, are of conservation concern. Families that include species of particular conservation concern include Eleutherodactylidae, Eublepharidae, Iguanidae, Phrynosomatidae, Xantusidae, Boidae, Colubridae, Natricidae, Emydidae, and Testudinidae (Tables 1, 2). The IUCN, SEMARNAT, and EVS categories are based on global or country-level assessments, and it is likely that there are amphibians and reptiles whose conservation status in Durango is not accurately assessed by the global level assessment. Additional assessments at the state level in Durango, and other Mexican states, are needed to establish conservation or management needs for states, or even regions.

To help determine which habitat types within Durango may house species of particular conservation concern, the conservation statuses of reptile and amphibian taxa in each habitat type found in Durango was summarized. None of the amphibians in the arid-semiarid habitats and Quebradas were in protected IUCN categories (VU, NT, EN, CE), 7.1% in the valleys, and 25% in the Sierra habitat. For SEMARNAT categories, 42.8% of amphibians in the arid-semiarid habitats, 26.7% in the valleys, 33.3% in the Sierra habitat, and 18.2% in the Quebradas were listed. For EVS, 100% of the amphibians in the arid-semiarid habitat were in the low category. Almost half (46.6%) of the amphibians in the valley habitat were in the low category, 40% in the medium category, and 13.3% in the high category. In the Sierra habitat type, 26.3% of amphibians were in the low category, 42.1% in the medium, and 31.6% in the high. For the Quebradas habitat, 45.4% were in the low and medium categories and 9.1% in the high. Based on this summary, it is clear that for amphibians, the Sierra habitat has the most at risk species and the arid-semiarid habitat has relatively fewer at risk species. For amphibians, therefore, the Sierra habitat would appear to be a priority target for conservation efforts.

For the IUCN listings, all habitat types had relatively few species of reptiles in the protected categories (arid-semiarid, 8.5%; valleys, 3.2%; Sierra, 3.8%; and Quebradas, 7.7%). However, 39% of reptiles in the arid-semiarid habitat, 41.9% from the valley habitat, 42.3% from the Sierra habitat, and 30.8% from the Quebradas habitat were in the protected SEMARNAT categories. For the arid-semiarid habitat type, 28.1% of reptiles were in the low EVS category, 43.8% in the medium, and 28.1% in the high. In valleys, 29% of the reptiles were in the low, 51.6% in the medium, and 19.4% in the high. Of the reptiles in the Sierra habitat type, 21.6% were in the low, 45.1% in the medium, and 33.3% in the high categories. For the Quebradas habitat type, 19.2% were in the low EVS category, 50% in the medium, and 30.8% in the high. In contrast to amphibians, at risk reptile species are more evenly distributed across the habitat types. Therefore, conservation efforts for reptiles should address all habitat types.

Three non-native species of amphibians and reptiles were documented in Durango: R. catesbeiana, H. turcicus, and I. braminus. Non-native species can negatively affect native herpetofaunal communities in Mexico (see Wilson and Townsend 2010). Of the three non-native species, R. catesbeiana is of particular concern. Rana catesbeiana is known to have many impacts on native communities as a competitor, predator, and disease vector on a global scale (reviewed in Moutou and Pastoret 2010; Kraus 2015), as well as in Mexico (e.g., Luja and Rodriguez-Estrella 2010; Becerra Lopez et al. 2017). The potential impacts of H. turcicus are less well documented, but its congener H. frenatus has affected native herpetofauna through competition (reviewed in Punzo 2005; Kraus 2015). The impacts of I. braminus are, to our knowledge, unstudied, even though it has been widely introduced around the world (see Borroto-Páez et al. 2015). There is thus the potential for these non-native amphibians and reptiles to have negative impacts on the native herpetofauna, and other organisms, of Durango. The extent of these potential impacts need to be evaluated further.

Hopefully, this list of amphibian and reptile species in Durango with their global and country-level conservation statuses will prompt further investigations into the herpetofauna of this state, which could provide the needed information to allow for state- or regional-specific, or even habitat type, conservation measures to be undertaken.