A new species of Trichomycterus endemic to the Ribeira de Iguape River basin, southeastern Brazil, was studied based on morphological and molecular evidence. This species had an outer layer of coloration composed of scattered, round, black or dark‐brown spots smaller or equivalent in size to the circumference of the eye; eight pectoral‐fin rays; 28–29 opercular odontodes; 54–56 interopercular odontodes; and supraorbital line of the laterosensory system not interrupted, with pores s2 absent. Two other species of Trichomycterus from the Ribeira de Iguape River basin are recorded, and their taxonomic status is discussed: Trichomycterus alternatus and Trichomycterus jacupiranga were not differentiated using molecular analysis but may be consistently distinguished based on morphology. The phylogenetic relationships of the co‐occurring species, T. alternatus and Cambeva zonata, were inferred using mitochondrial data, reinforcing the taxonomic status of these recently revised species that have a complex taxonomy. In addition, a new combination for Trichomycterus taroba with its inclusion in the genus Cambeva is recommended.

Ituglanis boitata, new species, is described from the rio Tramandaí system and rio Mampituba and Araranguá basins, southern Brazil. This new species is distinguished from congeners with the exception of I. bambui, I. boticario,                       I. paraguassuensis and I. proops by the supraorbital canal of the cephalic laterosensory system interrupted between nasal and frontal sections and the presence of pore s2 (vs. supraorbital canal uninterrupted and pore s2 absent). Ituglanis boitata     differs from these species in osteological characters, measurements and body coloration. Ituglanis boitata presents a              noticeable endemism in the Tramandaí-Mampituba freshwater ecoregion, a recognized biogeographic unit for freshwater fishes including other 22 endemic species. A discussion about the intraspecific variation in the cephalic laterosensory system within Trichomycterinae is also provided.

A new species of Ituglanis associated to the grasslands of the Pampa biome is described from the rio Uruguai basin, southern Brazil. The new species is distinguished from its congeners by the low number of ribs and by a unique color pattern composed of an outer layer with scattered round black blotches equivalent in size to the eye circumference over a reddish brown background on the lateral surface of the body. We provide the genetic sequences of the mitochondrial gene Cytochrome c Oxydase subunit I (COI) for three of the paratypes and discuss aspects about the recent discovery of the new species.Keywords: Genetype, Pampa Biome, Rio Ibicuí, South Brazilian Grasslands, Taxonomy.Uma nova espécie de Ituglanis, associada aos campos do bioma Pampa, é descrita para a bacia do rio Uruguai no sul do Brasil. A nova espécie distingue-se de todos seus congêneres pelo pequeno número de costelas e por um padrão de coloração único que consiste de manchas pretas arredondadas de tamanho equivalente à circunferência do olho sobre um fundo marrom avermelhado na superfície lateral do corpo. Sequências genéticas do gene mitocondrial Citocromo Oxidase subunidade I (COI) para três dos parátipos são fornecidas, e aspectos sobre a recente descoberta da nova espécie são discutidos.

The first occurrence of Phallotorynus victoriae is reported from the Uruguay river basin associated with the grasslands of the Pampa Biome, southern Brazil. The record includes only one specimen from a tributary to Ibicuí River located in the municipality of Uruguaiana, Rio Grande do Sul state. Key wordsBiodiversity; Ibicuí basin; gonopodium; Pampa Biome; taxonomy.

No abstract