Snakes of Cerrado localities in western Bahia , Brazil

We present a list of snake species found in 10 municipalities in the Cerrado of western Bahia state, Brazil. One hundred and twenty individuals of 46 species from seven families were examined. We also present a new state record for the genus Phalotris Cope, 1862 and a candidate new species for the genus Thamnodynastes Wagler, 1830.


INTRODUCTION
The Cerrado is the second largest morphoclimatic domain of Brazil, covering about 22% of the territory and surpassed in area only by the Amazon rainforest (Eiten 1972;Ab'Saber 1977;Oliveira and Marquis 2002).The Cerrado forms a continuous block in central Brazil but is also present as small enclaves within other domains, presumably as remnants of a past, more extensive distribution (Cole 1960;Carneiro Filho 1993;Barbosa et al. 2007;Werneck 2011).Harboring a rich and endemic biota that is highly imperiled by the expansion of commercial agriculture (Cavalcanti and Joly 2002;Klink and Machado 2005;Jepson et al. 2010), the Cerrado is considered a global biodiversity hotspot (Mittermeier et al. 2000;Myers et al. 2000).It is estimated that about 40% to 55% of the Cerrado has been converted to croplands, pastures and plantation forests (Mantovani and Pereira 1998;Machado et al. 2004;Sano et al. 2010); nevertheless, this transformation has received less attention than deforestation in the Amazonian and Atlantic rainforests (Ratter et al. 1997;Marris 2005).
The western Bahia region, within the Cerrado domain, is undergoing an agricultural development and has been drastically transformed from an economic backwater in the 1970s into one of the largest soybean producing areas in Brazil (Brannstrom 2005;Mendonça 2006;Santos 2008).This development has resulted in a dramatic decline of natural habitats in the region (Rocha et al. 2009;Santos and Epiphanio 2009;Passos et al. 2010;Flores et al. 2012).It is estimated that the Cerrado in western Bahia declined from 73% in 1986 to 40% in 2002, with an annual rate of loss of 2.6%, or 239 km 2 /year, while croplands and pastures increased annually by 18.3% (Brannstrom et al. 2008).A study using climate modeling algorithms revealed that the western Bahia region lies within a refuge of climate stability in the Cerrado, the Serra Geral de Goiás refugium (SGGR), suggesting it should receive high priority for conservation (Werneck et al. 2012).Unfortunately, like the Cerrado as a whole (Klink and Machado 2005), there are few protected areas in western Bahia: Parque Nacional das Nascentes do Rio Parnaíba, Estação Ecológica Serra Geral do Tocantins, Área de Proteção Ambiental Bacia do Rio de Janeiro, FLONA de Cristópolis, and Reserva de Vida Silvestre das Veredas do Oeste Bahiano (Agência Nacional de Águas et al. 2004).In addition, regional herpetofaunal assessments are incipient (e.g., Hamdan and Lira-da-Silva 2012)

MATERIALS AND METHODS
The region comprises the sub-basins of the rivers Carinhanha, Corrente and Grande, all of which drain into the left margin of the São Francisco River (Secretaria de Recursos Hídricos do Ministério do Meio Ambiente 2006).The topography is flat, with elevations ranging from ca. 750-950 m, on top of a vast plateau variously called Espigão Mestre, Serra Geral de Goiás, Chapadão Ocidental Bahiano or Chapadão Ocidental do São Francisco (Villela and Nogueira 2011;Grohmann and Riccomini 2012).This plateau consists predominantly of sandstones from the Urucuia group (Cretaceous) on top of predominantly limestone deposits of the Bambuí group (Neoproterozoic) (RADAMBRASIL 1982;Campos and Dardenne 1997;Iglesias and Uhlein 2009).Mean annual rainfall is concentrated between October and April and is highest (~1,400 mm) in the west, but decreases to ~600 mm close to the São Francisco River in the Sertaneja depression (Depressão Sertaneja) to the east (Agência Nacional de Águas et al. 2004).
The majority of the material used in this study was collected in 2009, 2010 and 2014 during wildlife Valdujo et al. (2009Valdujo et al. ( , 2011) ) found that (1) the amphibian assemblages in western Bahia are as diverse as those from the south-central portion of the Cerrado, (2) most species are typically found in Cerrado habitats, and (3) there are no regional endemics.Similarly, Recoder et al. (2011) recorded diverse reptile assemblages, but a large proportion of species had wide distributions with few local, Cerrado endemics.
Herpetofaunal sampling related to environmental assessment studies for hydroelectric projects has increased significantly in Brazil over the last 10 years, mainly in the north and west-central regions (Pavan and Dixo 2004;Vaz-Silva et al. 2007;Cintra et al. 2009;Silva Jr et al. 2009).In the Cerrado domain, these inventories have also been intensified because of the environmental licensing process; those in the west-central and northern regions of Brazil resulted from the construction of new hydroelectric power plants, while those in the Cerrado resulted from similar, but smaller licensing projects.Several other studies have also been conducted, involving research and university extension courses, or long-term studies in conservation units such as those of Recoder and Nogueira (2007)  A comparison between our study and previously published ones in other areas of the Cerrado domain was made.

RESULTS
One hundred twenty individuals comprising, 46 species of snakes from seven families (Table 1), were collected (Figures 2-5).The contacts between the Cerrado and semi-arid dry areas in northeastern Brazil are still poorly studied.Our inventory shows a large area of contact between the northeastern Cerrado and the Caatinga, including species from both domains in this contact zone.
We also discovered a presumed new species belonging to the genus Thamnodynastes Wagler, 1830 (Figure 3E), and Phalotris concolor (CHUNB 17435, 51553).This specimen, a male, with a combination of uniform light brown dorsal coloration, 1+1 temporal scales, blotched infralabial and gular region, 202 ventral scales and 36 subcaudal scales, falls within the variation described by Moura et al (2013).This is the first record of Phalotris from the state of Bahia and highlights the need for more taxonomic studies with this genus.

DISCUSSION
The average number of snake species found in each of the previous inventories (Table 2) is 36.The highest species richness, 61 (França et al. 2004(França et al. , 2008)), was found in Brasília in Distrito Federal.
Table 1 shows the number of species of snakes found in different Cerrado areas in Brazil, including small enclaves of Cerrado within the Caatinga domain (Freitas et al. 2012;Ribeiro et al. 2012).
Knowledge of the biodiversity of a region is the main tool for discussing conservation of ecosystems and wildlife populations.Our inventory shows that the Cerrado of western Bahia has a relatively high species richness of snakes for the region and is higher than the average found in 15 prior inventories conducted within the Cerrado domain.
The diversity of Cerrado snakes of western Bahia includes 14 typical predominant and almost exclusive species of the Brazilian Cerrado, 24 species of wide distribution in many areas of vegetation of Brazil, and only eight species typical and almost exclusive to the Caatinga domain.

Figure 1 .
Figure 1.An overview of the study area in the Cerrado of western Bahia.Red circles are sampling points.
Freitas et al. | Snakes of Cerrado localities in western Bahia, Brazil

Table 1 .
Freitas et al. | Snakes of Cerrado localities in western Bahia, Brazil assessments for small dams, transmission lines and railway lines.Altogether, they comprised approximately 50 days of fieldwork, divided into five field campaigns with two to four people, using time-limited active search on suitable habitats and roads.The inventory also included photographic records of one of the authors (LT), an ornithologist and resident of São Desidério for 10 years.We also used records from the Coleção Herpetológica da Universidade de Brasília.After collection, specimens were killed following the guidelines of the American Society of Ichthyologists and Herpetologists, fixed in 10% formalin, and subsequently deposited in the Museu de Zoologia da Universidade Estadual de Santa Cruz (MZUESC), Coleção Herpetológica da Universidade de Brasília (CHUNB) or Museu de Zoologia da Universidade de São Paulo (MZUSP) (Appendix 1).Collections in São Desidério were granted by Instituto Brasileiro de Snakes recorded from western Bahia, Brazil.

Table 2 .
Comparisons between different studies inventorying snakes in the Cerrado biome.Freitas et al. | Snakes of Cerrado localities in western Bahia, Brazil