A new species of Elachistocleis (Anura: Microhylidae) from the Andean Yungas of Argentina, with comments on the Elachistocleis ovalis – E. bicolor controversy E.O. Lavilla 1 , Marcos Vaira 2 , Liliana Ferrari 1 1 Instituto de Herpetología, Fundación Miguel Lillo, Miguel Lillo 251, 4000. Tucumán, Argentina e-mail: lavilla@unt.edu.ar; lilif@unt.edu.ar 2 Museo de Ciencias Naturales, UNSa Mendoza 2, 4400 Salta, Argentina e-mail: mvaira@cootepal.com.ar Abstract. Elachistocleis skotogaster spec. nov. is described from the Andean Yungas of Argentina. It is unique in the genus in having belly and legs densely spotted with brown, an uniformly dark brown dorsal mottled with black, absence of a light vertebral strip, a fold behind the mouth but not a postcommisural gland. Its natural history and advertisement call are brie y noted. Elachistocleis ovalis and E. bicolor are considered different species, and Buenos Aires, Argentina, is established as type locality for the latter one. Resumen. Se describe Elachistocleis skotogaster n. sp. de las Yungas andinas de Argentina. Se diferencia de las restantes especies del género por presentar vientre y región inferior de los miembros posteriores densamente punteada de castaño, la región dorsal castaño oscuro, punteada en negro, sin banda vertebral clara, y el área por detrás de la boca con un pliegue pero sin glándula postcomisural. Elachistocleis ovalis y E. bicolor son consideradas especies diferentes y se establece Buenos Aires, Argentina, como localidad tipo de esta última. Introduction The Neotropical Microhylid genus Elachistocleis comprises ve species: Elachistocleis bicolor (Guerín-Méneville, 1838), E. erythrogaster Kwet and Di Bernardo, 1998, E. ovalis (Schneider, 1799), E. piauiensis Caranaschi and Jim, 1983 and E. surinamensis (Daudin, 1802). Two of them, Elachistocleis ovalis and E. bicolor, are involved in a tremendous confusion since 1841. Later contributionsnot only did not solve the problem but contributed to increase the controversy (e.g. Duméril and Bibron, 1841; Boulenger, 1882; Mertens, 1929; Parker, 1934). © Koninklijke Brill NV, Leiden, 2003 Amphibia-Reptilia 24: 269-284 Also available online - www.brill.nl Downloaded from Brill.com 07/29/2024 12:18:34PM via free access