Amphibians and reptiles of the Calakmul Biosphere Reserve , México , with new records

We provide a list of amphibians and reptiles of the Calakmul Biosphere Reserve in the southern half of the Mexican Yucatan, in the state of Campeche. The study area was sampled through opportunistic, transect and pitfall trap surveys conducted for three successive years. These surveys resulted in a total of 2,359 amphibian and reptile encounters, belonging to 20 amphibian and 69 reptile species from 24 total families. We present herein the records for one snake, one chelonian and two salamander species not previously recorded in the area.


INTRODUCTION
Mexico is one of the most biologically rich countries on the planet (Mittermeier and Goettsch-Mittermeier 1997;Gárcia-Frapolli et al. 2009).This is due in no small part to the diversity found in the southern region of the Yucatan Peninsula, which is home to the largest expanse of mature, seasonal tropical forests remaining in Mesoamerica (Carr 1999;Vester et al. 2007).Unlike the majority of forest in the Yucatan Peninsula, the forest in Calakmul Biosphere Reserve, hereafter CBR, of Campeche, Mexico has not been used for large scale timber production nor has it been burned for farming and ranching.As such it is one of the last remaining stands of virgin forest in Mexico, being classified by UNESCO as World Heritage Site of Culture and Nature (UNESCO 2014).In spite of the recognized cultural and ecological value of CBR, few surveys have been conducted on its herpetofauna.
Beginning in 2012, annual biodiversity surveys have been conducted conducted in the CBR by Operation Wallacea, a UK-based non-governmental organization that specializes in biodiversity assessments and monitoring of protected areas through utilizing the expertise of university academics and students.We present herein the results of the herpetological (amphibian and reptile) surveys and discuss their conservation implications for the CBR.

MATERIAL AND METHODS
Our study was conducted in the CBR (18°21.921ʹN, 089°53.220ʹW; Figure 1), located in the Yucatan Peninsula in Campeche, México.CBR is a large expanse of tropical forest (723,000 ha of reserve and 384,000 ha of buffer zone) that is part of the Selva Maya (Mayan

Lists of species
flowing water in the form of a stream rather than semipermanent aguadas (temporary pond).KM20 served as the primary base camp and operation headquarters due to the park infrastructure already in place and was located in the transition zone from medium to tall canopy forest.KM27 and KM40 contained the largest and most numerous aguadas among our camps; while Dos Naciones, the southernmost camp, was characterized by the largest and most numerous fruiting trees.
Semi-permanent camps were constructed and utilized at five of the sites (Dos Naciones, KM20, Mancolona, Nadzca'an and Hormiguero).Camp locations were chosen for their accessibility during the wet season and because they cover the full geographical and vegetation range of the reserve.Each camp contained four, two km long transect lines for data collection.Transect surveys were conduct both in the day and at night and all surveys were replicated a minimum of four times.Transect surveys were alternated such that each transect had a minimum of 24 hours rest between surveys.All animals encountered on transect surveys were immediately captured, identified, photographed, when possible marked to avoid repeating counts and identify recaptures, measured and then released at the point of capture.Common, easily identifiable species Jungle) which encompasses parts of Mexico, Guatemala and Belize, spans over 10.6 million ha and is the largest continuous section of tropical forest in Mesoamerica (Vester et al. 2007).There is a notable precipitation gradient in the reserve, from 900 mm annually in the north to 1,400 mm annually in the south of the reserve; this has significant effect on forest structure and tree species composition (Vester et al. 2007).The majority of the reserve is composed of tropical semi-deciduous forest with a canopy ranging from 15 to 40 m, whereas the northern parts of the reserve are composed of tropical deciduous forest, with canopy of 8 to 20 m (Chowdhury 2006).
Data collection was carried out between June and August of 2012-2014 and included surveys in seven different sampling localities (Dos Naciones, KM20, KM27, KM40, Mancolona, Nadzca'an, and Hormiguero) within the CBR (Figure 1).Mancolona and Nadzca'an are located in the dry north of the reserve, and are proximal to buffer zones for the reserve.Both of these northern camps have few of the typical large fruiting trees (i.e., ramon (Brosimium alicastrum) and zapote (Manilkara zapota)) relative the core and southern areas of the reserve.Although situated in the relatively dry north, Nadzca'an was the only site with permanent (e.g., Ameiva undulata, Incillius valliceps) were simply counted after a minimum of ten individuals had been measured during a given survey.
At each camp two pitfall trap arrays composed of four buckets each disposed in a Y shape connected by 3 m long by 1 m high drift fences were constructed.In each location, one trap array was placed adjacent to a transect near an aguada, and one adjacent to a transect at least one km from an aguada (Figure 2).Traps were checked each morning and were left open for a minimum of three weeks.All animals captured in traps were immediately removed, identified, photographed, when possible marked to avoid repeating counts and identify recaptures and measured prior to release a safe distance away from the traps while still in the immediate area.
All data were collected by teams of students led by university academics and local indigenous experts.Due to permit restrictions within the Biosphere reserve no specimens were collected but digital photographs were taken and represent digital vouchers for all but two species.These digital vouchers are curated by Operation Wallacea, TJC and Pronatura Peninsula de Yucatan (PPY).Tissue samples in the form of scale, toe or tail clips that resulted from marking individuals were retained and deposited at the tissue collection of the lead author at the University of Mississippi.Additionally, collections of tissues as a by-product of marking individuals followed the University of Mississippi Institute for Animal Use and Care protocols: SOP 13-03 and SOP 13-04.

RESULTS
We recorded a total of 2,359 encounters during our surveys, representing 21 amphibian species included in seven families (Table 1) and 69 reptile species from 17 families (Table 2).All 19 and 65 species of amphibians and reptiles, respectively, previously described for CBR were observed (Lee 2000;Kholer 2008;Mandujuano et al. 2010;Cedeño-Vasquéz et al. 2010).The most species-rich   amphibian family was Hylidae (40% of amphibian species richness), while the most species-rich reptile families were Colubridae, Dipsadidae and Dactyloidae (23%, 22% and 13% of reptile species richness, re spec tively).The snake Ninia diademata; Figure 3, the turtle Kinosternon acutum; Figure 4 and two salamanders (Bolitoglossa mexicana, Bolitoglossa rufescens; Figure 5) were recorded during the study.None of these were previously reported for the CBR although all have been recorded 50 km to the south in Guatemala and to the west in the Mexican state of Chiapas (Lee 2000).

DISCUSSION
In our study, the total number of species found in the CBR represents about 37% of the herpetofaunal species richness observed in the Mayan jungle (188 species; Lee 2000).Of this number, nearly 14% of species occur only within the Yucatan Peninsula (e.g., Bolitoglossa yucatana; Coleonyx elegans).Knowledge of the assemblage and distribution of amphibians and reptiles in the Yucatan Peninsula is, therefore, of great importance when taking measures to preserve the fauna of this region, especially because site conservation may be one of the most effective means of reducing biodiversity loss (Eken et al. 2004).
Our results point out that only about 50% of the recorded species were recorded in three or more camps, suggesting significant differences on species richness and diversity within Calakmul, and therefore highlight the need for specific conservation measures that are adapted to each habitat type.Latitude-correlated rainfall differences among camps may be responsible for differences in local microhabitat differences (Stevens 1989;Lyons and Willig 2002), which may result in species     (Vitt et al. 2007;Garda et al. 2012).However, when considering family level variation (e.g., Colubridae, Hylidae) and, to some extent, genus level variation (e.g., Norops, Kinosternon), richness among our camps was even.
Overall species abundance and diversity appeared to follow the known precipitation gradient in the reserve.Camps in the wetter, central and southern portions of the CBR contained more herpetofaunal species as expected.Interestingly when only considering reptile species diversity the dry northern camp of Nadzca'an had a similar number of reptile species as the southern camps.We suspect this is due to the permanent stream located in the camp which provides suitable habitat to a variety of turtles as well as a water source for other reptiles while not providing suitable breeding habitat for many amphibian species that reproduce in temporary ponds.
Species which favour open or disturbed habitat (e.g., Sceloporus chrysostictus) were more abundant at the dry (open canopy) northern camps that are also situated along the edge of the buffer zone of the reserve.Although some frogs were found in or near human-made structures (e.g.Incillius valliceps) or small water reservoirs (e.g., Smilisca baudinii), the majority of individuals were found near aguadas.On the other hand, some species were recorded away from major water sources (e.g., Triprion petatsatus) in seemingly dry habitat.Future studies will specifically test the effect of forest structure, habitat disturbance and distance from aguadas on herpetofaunal community composition.
Guides to species of amphibians (Cedeño-Vasquez et al. 2010) and reptiles (Calderon-Mandujano et al. 2010) of the CBR have already been produced.However, these guides are not indexed and are only available in Spanish.Thereby, our study is the first published indexed species list for the region, and includes four new species that were not previously reported from CBR, and significant range extensions for these species.Future studies should be conducted in other seasons and considerable efforts should be directed toward fossorial amphibians and reptiles, which are hard to detect and may have not been encountered previously.would have been possible.We also thank the rest of the Operation Wallacea staff and student volunteers for logistical assistance and data collection.We thank SEMARNAT and the National Commission of Natural Protected Areas for providing permits.Permits issued by SEMANART and National Commission of Natural Protected Areas over the period of study as part of a long-term conservation project with Pronatura Peninsula de Yucatan were: SPGA/DGVS/05912/12 and SPGA/DGVS/12101/14.TJC would like to thank the University of Mississippi Graduate College for funding to support summer research and Lenin Arias Rodriguez for assistance with export permits.We thank the Editor and one anonymous reviewer for their helpful comments on the manuscript.

CheckFigure 1 .
Figure 1.Location of Calakmul Biosphere Reserve within the southern Yucatán Peninsula.Study sites within the reserve are also indicated.KM27 and KM40 are not shown due to their close proximity to KM20 and Zona Arqueologica respectively.Green shading on inset represents the protected reserve (core and buffer zones) and orange shading indicates the connected state reserves of Balam-kim and Balam-ku.

Figure 2 .
Figure 2. (A) Example of pitfall trap and drift fence array.(B) Typical semi-permanent aguada.(C) Graphical representation of transect and trap design where camp is indicated by yellow triangle, transects by dashed lines, aguadas by blue circles and pitfall and drift fence arrays by Xs.

Table 1 .
List of amphibians encountered in the CBR.*New records not previously reported for the area.** Digital voucher only.

Table 2 .
List of reptiles encountered and localities in the CBR.*New records not previously reported for the area.
Colston et al. | Herpetofauna of the Calakmul Biosphere Reserve