Geological and topographical conditions of the Sierras de Córdoba (Pampa de Achala) stress the peculiar environmental features of the isolated populations of its herpetological elements. A detailed serological and morphological study of the local representative form of the Andean <i>spinulosus</i> complex of toads, suggests its allopatric specific status. A new species of toad, <i>Bufo achalensis</i>, belonging to the <i>spinulosus</i> group is described, and some stricking morphological relationships with the Peruvian <i>arequipensis</i> toad by Vellard are reported.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Museo