Herpetofauna inside and outside from a natural protected area: the case of Reserva Estatal de la Biósfera Sierra San Juan, Nayarit, Mexico

Natural Protected Areas (NPAs) includes important species richness, and it is assumed that these are the best areas for biodiversity conservation. There are certain doubts, however, about the effectiveness of the NPAs in developing countries, where economic resources for conservation are scarce and NPAs are not monitored and managed efficiently. In the present study we assessed the species richness, diversity, abundance, and functional guilds of amphibians and reptiles inside and outside of the NPA Reserva Estatal de la Biósfera Sierra San Juan (REBSSJ), Nayarit, Mexico. Our results showed that species numbers of amphibian and reptiles were higher outside than inside the reserve, as well the individual number distributed among species, except for lizard species. Analyses of functional guilds showed that both richness and functional dispersion were greater in amphibians and reptiles outside the reserve. Likewise, outside the reserve we recorded a higher species number with some category of risk at the national level (NOM-059), international level (IUCN), and also by using the Environmental Vulnerability Score (EVS) algorithm. The results suggest that areas outside of the reserve are crucial to the maintenance of regional biodiversity, due to high complementarity with species composition inside of the reserves. These data can be used to implement conservation measures that include a new demarcation of the reserve and the consideration of surrounding areas to include a great number of species

New records of the snake Leptophis diplotropis (Günther, 1872) (Squamata: Colubridae) from Hidalgo State, México

We report three new records of the snake Leptophis diplotropis from the southeastern and northern regions of Hidalgo State, México. These records represent the first observations of this species in the state of Hidalgo, and represent a range extension of 122.7 km north from the nearest record in Tochimilco, Puebla, México. These new records of L. diplotropis represent the best knowledge of its distribution in the Sierra Madre Oriental

Why is the egg retention in oviparous species a step to viviparity?: an example with lizards

Se presenta una revisión sobre las hipótesis ecológicas y fisiológicas en la transición de la oviparidad a la viviparidad usando como grupo modelo a las lagartijas (Squamata). Además, se incluyen ejemplos de especies de lagartijas que prueban la retención de los huevos en el oviducto durante el desarrollo embrionario prolongado en altas latitudes y ambientes templados de montaña. Las hipótesis ecológica y fisiológica indican que el clima frío favorece la retención del huevo por tiempos prolongados y la disminución de glándulas calcáreas, favoreciendo el paso evolutivo a la viviparidad en este grupo de vertebrados. Actualmente, hace falta estudios con especies ovíparas que habitan ambientes templados de altas latitudes (climas fríos) y de ambientes templados de montañas que presentan retención de huevos en estadios avanzados.A review on the ecological and physiological hypotheses in the transition from oviparity to viviparity is presented using lizards (Squamata) as a model group. In addition, examples of lizard species are included that test the retention of eggs in the oviduct during prolonged embryonic development in high latitudes and temperate mountain environments. The ecological and physiological hypotheses indicate that the cold climate favors the retention of the egg for long periods of time and the decrease in calcareous glands, favoring the evolutionary passage to viviparity in this group of vertebrates. To date, studies are needed with oviparous species that inhabit temperate environments at high latitudes (cold climates) and temperate mountain environments that present egg retention in advanced stages

Allometric analysis of sexual dimorphism and morphological variation in two chromosome races of the Sceloporus grammicus complex (Squamata: Phrynosomatidae) from Mexico

Sexual dimorphism is a widespread feature in the Animal Kingdom. In lizards of the Sceloporus grammicus complex, studies of sexual dimorphism that analyze the allometric trajectories of body traits remain unexplored. Here we investigate sexual dimorphism in key phenotypic traits, including body size (snout-vent length, SVL) as well as head length (HL), head width (HW), and forearm length (FL). We use an allometric approach to detect differences in scale relationships among body parts in the S. grammicus complex in Mexico. We focus on two chromosomal races within this complex, F5 (2n = 34) and FM2 (2n = 46). In the complex, we found that males are larger than females in all morphological variables, and this pattern was confirmed in both races. We determined negative allometric trajectories (SVL vs. HL and HW), isometry (SVL vs. FL) and intersexual differences in the slopes of the SVL vs. HL and HW; the males showed steeper slopes. Thus, the growth of the head is more pronounced in males than females. Additionally, we found between-race differences in these trajectories (SVL vs. FL) and in all morphological variables (F5 lizards are larger than those of the FM2 race), which correlate with their chromosomal divergence. We discuss biological implications of our findings in relation to sexual selection and natural selection

Reproductive strategy of male and female eastern spiny lizards Sceloporus spinosus (Squamata: Phrynosomatidae) from a region of the Chihuahuan Desert, México

We examined the reproductive strategy of male (n = 84) and female (n = 62) S. spinosus from a single population in San Luis Potosí, México. The male reproductive cycle peaked in March and April and declined from May to September, and was not correlated with fat body mass, but was positively correlated with liver mass. The female reproductive cycle peaked in April and May and declined from June through November, and was not correlated with fat body mass, but was correlated with liver mass. Mean clutch size based on oviductal eggs was 17.5 ± 1.9 (n = 12), and was not correlated with female snout-vent length. Our results for S. spinosus are generally similar to those of other populations of the S. spinosus species group. However, there are differences in some traits (e.g., timing of the initiation of the female reproductive cycle; clutch size), suggesting that the S. spinosus group could serve as another model group within Sceloporus to explore ecological and evolutionary causes of among population life history variation

Amphibian life history in a temperate environment of the Mexican Plateau: dimorphism, phenology and trophic ecology of a hylid frog, Hyla eximia (=Dryophytes eximius)

The study of demographic and life history aspects of an organism provides valuable information for its conservation. Here, we analyze the phenology of the Mountain Treefrog Hyla eximia (= Dryophytes eximius) in a temperate environment of the Mexican Plateau. Females were larger in snout-vent length and body mass than males. The peak period of activity occurred in the rainy season (May–September), with amplexus and egg deposition occurring between June and July, and larval development from July to August. A logistic model best explained observed male growth patterns, while the Von Bertalanffy model better described female growth. Notably, males grew faster than females, although females reached a larger overall body size. The diet of this species is made up of 10 prey categories. The index of diet importance indicated that males feed mainly on Coleoptera and Diptera, while females feed on Coleoptera, Diptera, Hemiptera, and Aranea. Both females and males showed a significant abundance of plant material in their stomachs, suggesting that H. eximia might exhibit highly specialized feeding behavior. Reproduction was seasonal, and both female and male reproductive cycles are synchronized with the rainy season. These natural history characteristics provide information to better understand their responses to environmental conditions

The herpetofauna of Hidalgo, Mexico: Composition, distribution, and conservation status

The herpetofauna of Hidalgo, Mexico, is comprised of 203 species, including 42 anurans, 17 caudates, one crocodylian, 137 squamates, and six turtles. Here, the distribution of the herpetofaunal species are catalogued among the four recognized physiographic regions. The total number of species varies from 77 in the Mexican Plateau to 166 in the Sierra Madre Oriental. The individual species occupy from one to four regions (mean = 2.1). About 69% of the Hidalgo herpetofauna is found in only one or two of the four regions, which is of considerable conservation significance. The greatest number of single-region species occupies the Sierra Madre Oriental (25), followed by the Gulf Coastal Lowlands (15), the Trans-Mexican Volcanic Belt (6), and the Mexican Plateau (2). The Coefficient of Biogeographic Resemblance (CBR) indicates that the Sierra Madre Oriental and the Gulf Coastal lowlands share the most species (72), because of their adjacent geographic position and they contain a significant number of generalist species that occur in the Gulf lowlands of Mexico, southern USA, Central America, and/or South America. The two largest geographic regions in Hidalgo by area, Sierra Madre Oriental and Mexican Plateau, reflect opposite patterns in species richness (166 and 77 species, respectively) due to overall differences in the ecological characteristics between them. A similarity dendrogram based on the Unweighted Pair Group Method with Arithmetic Averages (UPGMA) depicts two distinct clusters, one between the Sierra Madre Oriental and Gulf Coastal Lowlands and the other between the Mexican Plateau and Trans-Mexican Volcanic Belt. The former cluster reflects the two regions sharing a substantial number of herpetofaunal species that occur on the Gulf lowlands of North America and Central America, as well as a few that enter South America. The second cluster is due to the two montane regions being adjacent to one another and their ecological similarities. With respect to the distributional categories, the largest number of species is that of the country endemics (104 of 203), followed by non-endemics (92), state endemics (four), and non-natives (three). The principal environmental threats to the Hidalgo herpetofauna are deforestation, livestock, roads, pollution of water sources, cultural factors, and diseases. The conservation status of each native species was assessed by means of the SEMARNAT (NOM-059), IUCN, and EVS systems, of which the EVS system was the most useful. The Relative Herpetofaunal Priority (RHP) method was also used to designate the rank order significance of the physiographic regions and the highest values were found for the Sierra Madre Oriental. Most of the five protected areas in Hidalgo are located in the Trans-Mexican Volcanic Belt, which is only the second most important region from a conservation perspective. In addition, only 78 of the 200 native species found in Hidalgo are recorded in total from the five protected areas. Finally, a set of conclusions and recommendations are offered for the future protection of the Hidalgo herpetofauna

The herpetofauna of Veracruz, Mexico: composition, distribution, and conservation status

The herpetofauna of the state of Veracruz, Mexico, currently consists of 359 species, including 76 anurans, 45 caudates, one caecilian, one crocodylian, 217 squamates, and 19 turtles. The distribution of the herpetofaunal species are catalogued here among the four recognized physiographic regions in the state. The total number of species ranges from 179 in the Sierra de Los Tuxtlas to 236 in the Sierra Madre Oriental. The number of species shared among the four physiographic regions ranges from 100 between the Gulf Coastal Lowlands and the Transmexican Volcanic Belt, to 190 between the Sierra Madre Oriental and the Transmexican Volcanic Belt. A similarity dendrogram based on the Unweighted Pair Group Method with Arithmetic Averages (UPGMA) depicts two distinct clusters, one between the Sierra Madre Oriental and the Transmexican Volcanic Belt, and the other between the Gulf Coastal Lowlands and the Sierra de Los Tuxtlas. The former cluster refects two adjacent regions in highland environments that share a substantial number of herpetofaunal species, and the latter cluster shares a sizeable number of wide-ranging, generalist, lowland species found on the Atlantic and Pacifc versants of Mexico and Central America. The level of herpetofaunal endemism is relatively high, with 182 of 359 species either endemic to Mexico or to Veracruz. The distributional categorization of the total herpetofauna is as follows: 169 non-endemic species; 138 country endemic species; 44 state endemic species; and eight non-native species. The 169 non-endemic species are allocated to the following distributional categories: MXCA (89), MXSA (30), MXUS (29), USCA (11), USSA (four), and OCEA (fve). The principal environmental threats to the herpetofauna of Veracruz include deforestation, livestock, roads, water pollution, myths and other cultural factors, diseases, invasive species, and illegal commerce. The conservation status of each native species was evaluated using the SEMARNAT, IUCN, and EVS systems, of which the EVS system proved to be the most useful. The Relative Herpetofaunal Priority method was employed to determine the rank order signifcance of the four regions, and this identifed the Sierra Madre Oriental as the region of greatest importance. Only six protected areas exist in Veracruz, most of which are located in the Gulf Coastal Lowlands, the region of least conservation signifcance. The area of greatest signifcance, the Sierra Madre Oriental, does not contain any protected areas. A total of 265 species have been recorded within the six protected areas, of which 138 are non-endemics, 89 are country endemics, 31 are state endemics, and seven are non-natives. Finally, we provide a set of conclusions and recommendations to enhance the prospects for the future protection of the herpetofauna of Veracruz

An updated list of the Mexican herpetofauna: with a summary of historical and contemporary studies

The growth in our knowledge of the diversity of the herpetofauna of Mexico has occurred over the period of approximately 445 years from the work of Francisco Hernández to that of a broad multinational array of present-day herpetologists. The work of this huge group of people has established Mexico as one of the most significant centers of herpetofaunal biodiversity in the world. This status is the result of a complex orography, in addition to diverse habitats and environments and the biogeographic history of Mexico. The current herpetofauna consists of 1,421 native and introduced species, allocated to 220 genera, and 61 families. This figure is comprised of 1,405 native species and 16 non-native species (as of April 2023). The non-native species include two anurans, 13 squamates, and one turtle. The level of endemism is very high, presently lying at 63%, with this level expected to increase with time. Species richness varies among the 32 federal entities in the country, from a low of 50 in Tlaxcala to a high of 492 in Oaxaca. Amphibian species richness by state-level can be envisioned as comprising three levels of low, medium, and high, with the lowest levels occurring in the Peninsula of Baja California, a group of seven states in north-central and central Mexico, and a group of three states in the Yucatan Peninsula, with the highest levels occupying the southern states of Guerrero, Puebla, Veracruz, Oaxaca, and Chiapas, and the medium level in the remaining states of the country. Reptile species richness also can be allocated to three categories, with the lowest level occupying Baja California Sur, a group of central states, and the states of the Yucatan Peninsula, and the highest level found in a cluster of the states of Veracruz, Guerrero, Oaxaca, and Chiapas. Knowledge of the Mexican herpetofauna will continue to grow with additional studies on systematics, conservation, and the construction of checklists at various levels

Diversidad de reptiles en tres tipos de vegetación del estado de Hidalgo, México Diversity of reptiles in three vegetation types of the Hidalgo state, México

La zona sureste del estado de Hidalgo presenta diversos tipos de vegetación, como el bosque mesófilo de montaña, bosque de pino-encino y bosque de pino, con alta riqueza de reptiles. En este estudio, se analizó la diversidad alfa y beta de los reptiles en los 3 tipos de vegetación presentes en la zona sureste. Durante el periodo de recolección, de junio 2008 a agosto del 2009, se realizaron 12 salidas, 1 por mes, con duración de 3 días cada una. La diversidad de reptiles está compuesta por 25 especies, incluyendo un registro nuevo para el estado, la culebra Thamnophis scaliger. El bosque mesófilo de montaña (BMM) presentó la mayor riqueza, con 15 especies, seguido del bosque de pino (BP), con 13, y el bosque de pino-encino (BPE), con 12. Las asociaciones realizadas entre el BMM-BP y BMM-BPE presentaron la más alta disimilitud en especies, y el menor valor fue para el BPE-BP. Este estudio muestra la riqueza y distribución de las especies de los reptiles en los diferentes tipos de vegetación del sureste del estado y presenta nuevos registros de especies para la entidad. El conocimiento de la riqueza de especies por tipos de vegetación de este estudio sienta las bases sobre la biodiversidad, lo que ayuda a plantear estudios dirigidos a la conservación de este grupo.The southeast of Hidalgo in Mexico includes various vegetation types, such as cloud forest, pine-oak forest and pine forest, all harbouring a high species richness of reptiles. In this study we analyzed the alpha and beta diversity of reptiles in 3 vegetation types in the southeast of the state. The field work period was from June 2008 to August 2009, comprising 12 sampling periods of 3 days, 1 per month. The diversity of reptiles is composed of 25 species, reporting the snake Thamnophis scaliger as a new record for the state. The cloud forest (CF) has the highest richness, with 15 species, followed by pine forest (PF), with 13, and finally, the pine-oak forest (POF), with 12 species. The associations between the CF-PF and CF-POF showed the highest dissimilarity in species, and the lowest the POF-PF. This study shows the richness and distribution species of the reptiles in the different vegetation types from southeast of the state, presents new records of species from the state and provides the basis for future studies on the biology of some species of reptiles in the area. The knowledge of species richness by vegetation types from this study provides the basis on the biodiversity that help to raise studies directed to the conservation of this group