Reptiles and amphibians of a poorly known region in southwest Amazonia

The Amazon is the largest tropical forest of the world and it is extremely rich in biodiversity. However, some portions of the biome are still poorly known. This work presents an inventory of the herpetofauna of Boca do Acre municipality, a still preserved region located in southwest Amazonas state. The inventory was carried out in two periods, a sampling during the middle of the rainy season and another one at the end of the rains. Diverse survey methods were employed, such as pitfall traps, diurnal and nocturnal visual searches, car searches on the BR 317 highway, and opportunistic registrations. We recorded 56 amphibians and 53 reptiles during the ! $ % & '( )+ $ / )4( road, being snakes principally affected by road-kills. The species accumulation curves did not reach stability, indicating that the inventory was not complete. Our results show the high species richness of this region, its importance for the Amazonian biodiversity, and the urgency of its preservation.

The southwest of Amazonia contains a high diversity of amphibians and reptiles, but the studies on this region are very incipient (Azevedo-Ramos and Galatti, 2002). The region is drained by three major tributaries of the Amazon River: Juruá, Purus, and Madeira. The most precise inventories show a richness of at least 140 species for Alto Juruá (Souza et al., 2002;Souza, 2009), more than 90 species for Médio Madeira (Heyer, 1977;Vogt et al., 2007), and more than 110 species for Alto Purus (Rodríguez, 2003).
Inventories are important tools for Amazonian conservation, since biological surveys stimulate the discovery of new species, revealing endemic areas and the current levels of biodiversity. Consequently, conservation efforts can be appropriately directed towards the biome (Kress et al., 1998;Soares-Filho et al., 2006). In this study we present a preliminary list of amphibians and reptiles of Boca do Acre municipality, which has previously been recognized as a priority area for herpetofauna surveys in Brazilian Amazonia (Azevedo-Ramos and Galatti, 2001;Vogt et al., 2001).

Study area
The municipality of Boca do Acre is located in southwest Amazonas state, a neighbor of the municipalities of Labrea and Pauini, and of Acre State. The region comprises 22,349km 2 , with altitudes reaching 100 to 150m. The climate is type Am in the Köppen FODVVL¿FDWLRQ 1LPHU DQG SUHFLSLWDWLRQ LV 2,000mm per year, mostly between October and April. The Acre River and Purus tributaries Inauini and Pauini are the principal rivers that drain the region. The BR317 highway crosses the entire municipality, connecting the town of Boca do Acre, AM to Rio Branco, AC.

Data collection
The study was conducted in two periods: i) 04 to 13 January 2008 and ii) 31 March to 12 April 2008, totaling 23 sampling days in the middle and end of the rainy season, respectively. In both periods, four sampling methods were applied: car searches along the BR317 (approximately 1000km were covered during the study, mostly at the end of the day or in the evening), pitfall traps, visual and acoustic surveys (approximately 56h surveys), and incidental encounters (Heyer et al., 1994;Franco et al., 2002). The same six sites were surveyed in both sample periods. For pitfall traps, we used 40 buckets (20L) with drift fences in each period. The pitfalls were open during the entire inventory and were checked every day. Voucher specimens were collected and Reptiles and amphibians of a southwest Amazonia region FIGURE 1: Study area showing the municipality of Boca do Acre, state of Amazonas, the six sampling sites along the BR317 highway, and the two principal rivers, Purus and Acre.

Data analysis
The collection effort was evaluated by species rarefaction curves calculated using EstimateS 8.0.0 Software with the non-parametric Mao Tau estimator after data randomization 1000 times without replacement &ROZHOO 7KH ¿UVW FXUYH ZDV FDOFXODWHG XVLQJ WKH species richness collected by all sampling methods. We calculated a second curve using the species collected only in pitfall traps, the usually comparable sample method. In addition, we used the Chao 2 richness estimator to determine the expected richness of this area.

Results
We recorded 56 species of amphibians and 53 UHSWLOHV GXULQJ WKH ¿HOGZRUN 7DEOH )LJXUHV DQG Three other amphibian species and one snake collected in the same region by Marilene Vasconcelos da Silva and Moisés Barbosa de Souza (Universidade Federal do Acre) were added to the list, totalizing 59 amphibians and 54 reptiles for the region.  Phyllodactylidae, Podocnemididae, Testudinidae, Typhlopidae (one). Species rarefaction curves did not show asymptotic tendencies, indicating that the inventory was not complete ( Figure 5).
We recorded seven species of amphibians and 31 reptiles in the searches on BR317 highway (Table 1). The toad Rhinella marina was the species most impacted by the highway, with seven dead individuals. More species were found dead on the road (DOR -53%) than alive (AOR -47%), and snakes were more susceptible to being killed by cars (21 out of 26 snake species found on the road were DOR). Turtles and crocodilians were commonly found in ponds and lakes near the highway, but only two individuals of Caiman crocodilus were seen crossing the BR317.

Discussion
The number of amphibians and reptiles recorded during the study indicates a high diversity in the region. Previously, Azevedo-Ramos and Galatti (2002) pointed to the region among the rivers Jurua, Purus and Madeira as a priority area for amphibian conservation in Amazonia due to the high diversity. The amphibian richness found in Boca do Acre can be compared to that from other studies on Amazonia such as Manaus/Ducke  Vogt et al., 2007). Despite the high richness, some species that are generally common throughout Amazonia were not found, such as Hypsiboas boans, Hypsiboas calcaratus, and Dendrophryniscus minutus, suggesting an increase in the number of species WR EH LGHQWL¿HG LQ IXWXUH VWXGLHV $OVR IRU UHSWLOHV RXW of two species of crocodilians recorded, local people frequently indicated the presence of the black caiman Melanosuchus niger in larger rivers. In addition, another six species of turtle had already been found in the Acre and Purus rivers Chelonoidis carbonaria, Podocnemis expansa, Podocnemis sextuberculata, Peltocephalus dumerilianus, Chelus fimbriatus, and Phrynops geoffroanus (Vogt, 2003;Vogt et al., 2007) despite the fact that we were unable to register them.
Snakes and lizards have a high richness in Amazonia, reaching more than 60 species for snakes and 30 for lizards (Ávila-Pires et al., 2007). Nevertheless, the secretive habits and lower abundance of many species, as ZHOO DV DQG WKH ODFN RI HI¿FLHQW WUDSV PDNH WKH VDPSOLQJ RI HQWLUH VQDNH DQG OL]DUG FRPSRVLWLRQV GLI¿FXOW LQ VKRUW time inventories. Comparing the richness with that from other long term inventories, such as those from Manaus/ Ducke (66 species - Oliveira, 1998), Cusco Amazônico (51 -Duellman, 2005), and Espigão do Oeste (56 - Bernarde and Abe, 2006), the snake fauna of Boca do Acre are still incipient. The same occurs with lizards, comparing to Manaus/Ducke (32 species -Vitt et al., 2008), Cusco Amazônico (26 -Duellman, 2005, and Espigão do Oeste (29 -Macedo et al., 2008). The richness of snakes and lizards will certainly increase with the addition of new inventories in the region. Moreover, this area has ample potential to present unknown species. We captured a different snake species of the Liophis genus that requires further studies, and we saw one specimen that looked similar to Tupinambis longiventris, EXW ZH ZHUH XQDEOH WR FRQ¿UP WKH LGHQWL¿FDWLRQ %HFDXVH this specimen was so different to Tupinambis teguixin, we named it Tupinambis sp.
In addition, species rarefaction curves did not show an asymptotic tendency during the work. The addition of several species in the last sample days, such as Ctenophryne geayi, Philodryas viridissima, Typhlonectes compressicauda and Hypsiboas microderma, could be responsible for the lack of curve stability. The effectiveness of pitfall traps depends on the design of the array, and the number and size of the traps (Cechin and Martins, 2000). Larger pitfall traps plus another kind of trap would be useful to capture other amphibian and reptile species in future studies. However, despite the fact that the samples are not complete, the high richness already found in this work shows the importance of the Boca do Acre region for the Amazonian diversity of reptiles and amphibians.
Regarding the geographic distribution of the species sampled, most of them are widely distributed in Amazonia (47% amphibians and 53% reptiles), or can exceed the range out of Amazonia to other biomes (17% amphibians and 28% reptiles). Other species have a distribution that is restricted to west or south Amazonia. The major presence of widely distributed Amazonian species has been found by previous studies in other regions of southwest Amazonia (Rodríguez, 2003).
No species recorded in this work is included in the Brazilian list of species threatened by extinction (Machado et al., 2005). However, Aromobatidae frogs (Allobates femoralis and A. marchesianus), Dendrobatidae frogs (Ameerega hahneli, A. trivitata, and Ranitomeya biolat), turtles (3RGRFQHPLV XQL¿OLV and Chelonoidis denticulata), crocodilians (Caiman crocodilus and Paleosuchus palpebrosus), common tegu (Tupinambis teguixin), boid snakes (Boa constrictor, Epicrates cenchria, Eunectes murinus, and Corallus hortulanus) and mussurana (Clelia clelia) are listed in CITES Appendix 1 (list of species that are not necessarily now threatened with extinction, but that may become so unless trade is closely controlled -CITES, 2008). In addition, the turtles 3RGRFQHPLV XQL¿OLV and Chelonoidis denticulata are also listed as vulnerable on the IUCN Red List of Threatened Species version 2.3, due to the population reduction, the decline in the quality of the habitat, and the potential level of exploitation. In addition, the entire biodiversity of Amazonia is severely threatened by the increase in deforestation rates (Fearnside, 2005).
All over the world, roads and highways have been radically changing natural landscaping and affecting the animal population dynamics (Lodé, 2000;Trombulak and Frissell, 2000). The principal road impacts on herpetofauna are the road-kill level and the barriers that LVRODWH SRSXODWLRQV $QGUHZV 6QDNHV ¿JXUH DV the principal victims of road-kills due to their long body shape, their slow terrestrial locomotion, and the use of roads as thermoregulation sites (Rosen and Lowe, 1994;Dodd et al., 2004). More than 80% of snake species found in this work had some individuals registered on the highway, and they were mostly dead, indicating that the highway can be very prejudicial to this group.
In Amazonia, roads and highways are considered to be the main vectors of biome occupation and represent a great dilemma: while reducing population isolation, they are also responsible for deforestation, forest IUDJPHQWDWLRQ DQG ¿UH LPSDFW 1HSVWDG DQG &DUYDOKR 2001;Fearnside, 2005). The municipality of Boca do Acre is located in the Amazonian deforestation arc, and the BR317 highway may be prejudicial to the forest biodiversity. The priority efforts of conservation, such as zoning, protected areas, and governmental programs, are essential to the preservation of this high richness and extremely important Amazonian region.