The Proceratophrys bigibbosa species group is characterized by the presence of postocular swellings and absence of hornlike palpebral appendages. A new member of this group is described from Rio Grande do Sul, southern Brazil. Proceratophrys brauni sp. nov. is known from the southern regions of the Serra Geral, where it inhabits small streams in subtropical rain forests. It is characterized by the pointed snout, development of palpebral tubercles, and black ventral surface spotted with red. Its body size is intermediate between the smaller Proceratophrys avelinoi and the larger P. bigibbosa, both being redescribed here. Life histories of these three species and advertisement calls of P. bigibbosa and P. brauni are briefly described. An identification key to the members of the bigibbosa group is provided, and new distributional data are given. The type locality of P. avelinoi is specified, and Proceratophrys cristinae is considered a junior synonym of P. bigibbosa.