# Introduction he frog Elachistocleis bicolor Guérin Méneville, 1838 (Figure 1) belongs to the Microhylidae family (Lavilla et al. 2003; Rodrigues et al. 2003). The taxonomy of the species from the genus Elachistocleis are controversial and have undergone several changes (Lavilla et al. 2003; Thomé and Brasileiro 2007). Lavilla et al. (2003) remove E. bicolor from synonymy with E. ovalis Schneider 1799, which is widely distributed in South America (Frost 2009). The occurrence of E. ovalis in syntopy with other congeneric species of the genus and also taxonomically problematic can lead to unreliable identifications (Kwet and Di Bernardo 1998;Lavilla et al. 2003). According to De La Riva et al. 2000, considerable confusion took place in the past regarding the identity of E. bicolor vs. E. ovalis, whose main external difference is the ventral coloration (see Frost 1985). Today most authors apply the name E. bicolor to the frogs with an immaculate venter (De La Riva et al. 2000). The geographic distribution of this specie extends over several biomes, including Amazonia, In this work we report the first record of E. bicolor for the state of Rondônia, in southwestern Brazil, in a transitional region between the Cerrado and the Amazonian forest biomes. One male and three female of E. bicolor were collected at the municipality of Porto Velho, state of Rondônia, in an area of forested land on a private farm (08°43'09" S, 63°51'64" W), on 13 February 2009 by DBH. Specimens were identified according to De La Riva et al. (1996,2000), Frost (2009), and Rodrigues et al. (2003). These new records extend the geographic distribution of E. bicolor about 350 km eastwards from closest records in Beni, Bolivia (10°58'59.98" S, 66°06'00" W) and 715 km southwestwards from closest records in Amazonas, Brazil (03°18'15" S, 60°37'03" W) (Figure 2). Voucher specimens were deposited in the anuran ![Chaco, Cerrado, Pampa and Pantanal in Argentina (Céspedez et al. 2001; Lavilla et al. 2003; Aceñolaza et al. 2004; Kacoliris et al. 2006; Echeverría et al. 2007; Baldo et al. 2008; Duré et al. 2008; GBIF 2008), Bolivia (De la Riva et al. 1996, 2000; Reichle 1997; Reichle and Kohler 1998; GBIF 2008), Paraguay (Brusquetti and Lavilla 2006; GBIF 2008), Peru (MVZ 1999), Uruguay (Lavilla et al. 2004; Maneyro and Beheregaray 2007; Canavero et al. 2008) and Brazil. In Brazil, this species was reported to occur in the States of Amazonas (Gordo 2003; Lima et al. 2006; GBIF 2008), Distrito Federal (Lima and Costa 2006; Camargo and Aguiar 2007), Goiás (Bastos et al. 2003), Mato Grosso do Sul (Strüssmann et al. 2000; Gordo and Campos 2003; Rodrigues et al. 2003; Ávila et al. 2004; GBIF 2008), Paraná (Conte and Rossa-Feres 2006, 2007; Shibatta et al. 2009), Rio Grande do Sul (Braun and Braun 1980; Kwet and Di-Bernardo 1998; Colombo et al. 2008; Moreira et al. 2008; Santos et al. 2008; Quintela et al. 2009), Santa Catarina (GBIF 2008; Lucas and Fortes 2008) and São Paulo (Bernarde and Kokubum 1999; Vasconcelos and Rossa-Feres 2005; Silva et al. 2008) (Figure 2).](image-2.png "") 12![Figure 1 : Elachistocleis bicolor (female) showing the ovoid body, small and triangular head, dark brown to yellowish brown back with a white to light yellow stripe that extends from the nose to the urostylus region, immaculate yellow belly (the gular region is black in males), and a thin reddish-brown line in the back of the thighs](image-3.png "Figure 1 :Figure 2 :") ![](image-4.png "") ## Acknowledgements The authors are grateful to Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) for de license expedition (17983-2), Fundação de Tecnologia do Acre (FUNTAC) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support. * PGAceñolaza HEPovedano ASManzano JDMuñoz ; JIAreta AL RVirgolini Biodiversidad Del Parque Nacional Pre-Delta 2004 * Miscelánea 12 * Riqueza e densidade de vocalizações de anuros (Amphibia) em uma área urbana de Corumbá RWÁvila VLFerreira 2004 Mato Grosso * BrasilSul Revista Brasileira de Zoologia 21 4 * DBaldo CTomatis MVSegalla 2008 * New country record, geographic distribution map and advertisement call AnuraAmphibia LeptodactylusLeptodactylidae Furnarius Check List 4 2 * Anfíbios da Floresta Nacional de Silvânia, estado de Goiás RPBastos JA OMotta LPLima LDGuimarães 2003 Stylo Gráfica e Editora 82 Goiânia * Anurofauna do Município de Guararapes, Estado de São Paulo, Brasil. 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