Herpetofauna of protected areas in the Caatinga II: Serra da Capivara National Park, Piauí, Brazil

: We provide a list of amphibians, lizards, chelonians, and snakes collected during a 30-day expedition to the Serra da Capivara National Park, Piauí State, Brazil. Thirty-seven pitfall trap arrays composed of 4 buckets each, along with glue traps, funnel traps, and haphazard searches, were used to sample the herpetofaunal diversity. We recorded 17 species of lizards, 1 caecilian, 1 chelonian, 7 frogs, and 11 snakes. Rarefaction curves suggest that local biodiversity is still underestimated. An atypical drought during the period of study may have contributed to lower captures of certain groups, especially amphibians and snakes. The presence of water-dependent and forest-dependent species within local canyons (“Boqueirões”) suggests that these areas harbor faunas associated with relictual rainforest fragments and need to be better studied and managed accordingly.

. Schematic map showing study site location and the ten sampled points. Points 1 and 2 refer to the pitfall trap arrays trails, while points 3-10 were sampled by haphazard searches. and forms deep, long canyons commonly known to local people as "Boqueirões". The vegetation in these canyons is composed of semi-deciduous, mesic forests with tall canopy cover (Figure 3). Inside the park there are no natural water bodies, but a system of artificial water channels and ponds is used to provide water to animals by the park administration. We sampled squamates, turtles, and amphibians from May 6th to June 6th, 2012 using active random searches by four experienced collectors for at least 8 hours per day across ten different sampling points, and two lines of pitfall trap arrays ( Figure 1). We installed 37 pitfall trap arrays composed of four 30 L buckets each disposed in a Y shape, with one central bucket and three on the extremities, connected by three 6 m drift fences built with plastic sheets (Figure 4) (Corn 1994;Cechin and Martins 2000). We placed the trap arrays in a straight line, 20 m apart. At each drift fence, we placed two funnel traps (one on each side of the fence), totaling 6 funnel traps per array. We also placed four glue traps on each trap array, on several microhabitats (two on the ground and two on the vegetation, and across fallen branches). Traps were placed in two trails in separated regions of the Park, with 18 and 19 arrays each (Figure 1, points 1-2).
Total sampling effort was 30 days, 26640 hours of trap arrays and 960 hours of active random searches. Specimens were killed with lidocaine (applied to the abdomen of amphibians or injected into reptiles), fixed in a solution of 10% formalin and preserved in a 70% ethanol solution. Specimens were collected according to permits granted by appropriate agencies to AAG (SISBIO # 33402-1) and TBC (SISBIO # 29550-2). All specimens are deposited at Coleção Herpetológica da Universidade Federal da Paraíba (CHUFPB) and Coleção Herpetológica do Laboratório de Anfíbios e Répteis da UFRN (CLAR-UFRN). To evaluate the quality of our sampling effort, we produced rarefaction curves for lizards, amphibians, and all the herpetofauna combined (amphibians, lizards and snakes), based on individuals (Gotelli and Colwell 2001), using EstimateS 8.2.0 (Colwell 1994). The curves were obtained through 1000 resamplings of the original data, with no reposition.
None of the three rarefaction curves reached the asymptote ( Figure 12). Despite the large sample size and the connection to Chao2 estimator curve, the rarefaction curve for lizard species is still rising. The reason for this ascendance can be a lack of a few species on our survey, as we did not collect at least two lizard species (Calyptommatus sp. and Gymnodactylus geckoides) recorded for this study site based on previous unpublished data. As expected due to climate conditions during our survey, the amphibian species rarefaction curve is still rising and far from Chao 2 estimator curve.

Discussion
The lizard richness at PARNA Serra da Capivara is relatively high when compared to the majority of studies on other Caatinga sites. Few Caatinga sites have comparable lizard diversity, varying from 14-21 species (Vitt 1995;  Araújo et al. 2005;Gariglio et al. 2010;Moura et al. 2010). Instead, family and genus richness comparisons reveal quite similar results among Caatinga sites. For example, Teiidae, Tropiduridae and Gekkonidae, which exhibit both high diversity and abundance, presented similar patterns (many species shared between areas) among study sites in Caatinga (Vitt 1995;Loebmann and Haddad 2010;Garda et al. 2013). On the contrary, in lizard families such as Gymnophthalmidae, the Caatinga sites contain a similar number of species, but of different taxa.
Perhaps these differences can be related to habitat heterogeneity, such as the presence of forested areas, rocky outcrops, or open, arbustive ones. This endorses the importance of protected areas throughout the Caatinga to protect lizard species. Differences in local microhabitat may be responsible for such species variation among areas (Vitt et al. 2007;Garda et al. 2012), and the extremely small area protected by these reserves is likely not enough to protect all the lizard diversity in the biome. Cnemidophorus venetacaudus was recently described and was known only from Serra das Confusões National Park (Arias et al. 2011). We extend its distribution 100 km west from the type locality. Two other species reported herein, the gymnophthalmid Procellosaurinus erythrocercus and the tropidurid Stenocercus squarrosus, are reported for few localities in the Caatinga (Ribeiro et al. 2009;Delfim et al. 2011;Freitas and Veríssimo 2012). Furthermore, Colobosaura modesta is commonly found in the Cerrado biome (Colli et al. 2002;Brites et al. 2009), and can also be found in elevated relictual wet forests on Caatinga, known as "Brejos de altitude" (Borges-Nojosa and Caramaschi 2003). Its presence in PARNA Serra da Capivara may be related to some shared floristic and climatic relationships between Serra da Capivara and the Cerrado Biome, as they both share a sandy soil, to which this species is commonly associated, but they also both contain wet forested areas, the "Boqueirões" (Lemos and Rodal 2002).
Because of the shape of our rarefaction curve for amphibians, and supported by our field observations, we believe that climatic conditions in the area were atypical during our fieldwork. Despite collecting only a few amphibian species during the survey, we were still able to obtain some relevant information for a few taxa. One frog species, Leptodactylus aff syphax, was recently collected at Serra de Baturité and Ubajara National Park, both in Ceará State, (Loebmann and Haddad 2010). Furthermore, Siphonops sp. is the first caecilian registered for Piauí State, and one of the few for the Caatinga (Maciel et al. 2013;Miranda et al. 2013). Most of the frogs were found in or near human-made small water reservoirs (locally called "bebedouros"). These reservoirs are used to provide water to birds and mammals that occur in the area, and are refilled with water throughout the dry season. There are over 100 of these "bebedouros" in the area, they provide shelter and may positively affect amphibians in the area.
The severe drought in the region also affected the snake sampling. Snakes are comparatively harder to find and collect than frogs and lizards because of low abundances, secretive habits, and lack of efficient traps, and require longer inventories before a satisfactory result can be achieved (Shine 1991). Nevertheless, we still collected a reasonable portion of the species known to occur in Caatinga habitats from Piauí State (Rodrigues and Prudente 2011). The individuals of Thamnodynastes we collected were all from an undescribed species known as Thamnodynastes sp2 (sensu Franco and Ferreira 2002). It is important to highlight that Corallus hortulanus, an arboreal species commonly associated with wetter forested areas, was collected only in the mesic forests in one of the "Boqueirões" (along with several amphibians and the caecilian).
Even with the survey effort made, our sampling is still incomplete. This may be a result of the atypical drought in the region that had been ongoing for almost one year. Furthermore, besides our efforts not being enough to stabilize rarefaction curves for the region we sampled, PARNA Serra da Capivara is one of the largest protected areas in the Caatinga, and some areas which harbored different vegetation and soil types were logistically difficult to reach. Nevertheless, our study is the first published species list for this study site and one of the few for the Caatinga in Piauí State. We were also able to collect a reasonable portion of lizard diversity in the area. In addition, we provide relevant information on the distribution of some data deficient/rare species of reptiles and amphibians. We suggest that future surveys should be conducted in the wet season and considerable efforts should be directed to other regions (e.g. different soil and vegetation types) in order to achieve a better estimate of the herpetological diversity of PARNA Serra da Capivara.      Acknowledgments: We are in debt to all students and guest professors participating in the course Biologia dos Répteis (a joint course offered by UnB, UFPB, and UFRN) for help during fieldwork. We also thank C. R Simões for editing photographs. We are grateful to the crew of "Parque Nacional Serra da Capivara" for logistic and personnel support during our fieldwork. DOM thanks the University of Texas at Austin and Eric Pianka for providing conditions to finalize this manuscript. GCC thanks CNPq grants 302776/2012-5 and 563352/2010-8. This work was fully supported by a grant from CNPq/ICMBio to AAG entitled "Representatividade da Herpetofauna em Unidades de Conservação da Caatinga: Diversidade, Filogeografia e Relações com Biomas não Florestais Brasileiros" (Processo # 552031/2011-9).