A new species of bufonid toad in the genus Melanophryniscus, from the province of Misiones, northeastern Argentina, is described. It is included in the stelzneri group and is most similar to Melanophryniscus atroluteus than to any other species. Melanophryniscus sp. nov. is distinguished, by having a uniformly brown dorsal coloration, numerous white spots along the mandibular arch; the pupil surrounded by a golden ring; the iris gold, finely spotted with dark brown; and the frontoparietal fontanelle widely exposed anteriorly. Moreover, the advertisement call of the new species is noticeable longer than the call of M. atroluteus and has a higher dominant frequency. The Melanophryniscus species present in Misiones are discussed and several areas of syntopy are reported.