Two New Species of the Genus Melanophryniscus (Amphibia: Anura: Bufonidae) from Pampa Grasslands of Argentina

Two new species of small-sized terrestrial toad of the genus Melanophryniscus from the highland grasslands of the Ventania and Tandilia Mountain Systems in Buenos Aires province, Argentina, are described. We assign provisionally Melanophryniscus diabolicus sp. nov. (Ventania mountains) and Melanophryniscus nigricans sp. nov. (Tandilia mountains) as both belonging to the Melanophryniscus stelzneri group. The new species differs from other congeners by a distinctive combination of characters: dorsum dark black, tympanum concealed, venter blackish, and distribution on highland rocky grasslands in the mountains of Tandilia (M. nigricans sp. nov.), and on highland rocky grasslands in the mountains of Ventania and coastal dune grassland (M. diabolicus sp. nov.). Moreover, the advertisement call of the new species is noticeable different between species and close related species M. atroluteus and M. montevidensis. Both species have experienced local extinctions and should be categorized as threatened species.