Taxonomic review of Rineloricaria (Loricariidae: Loricariinae) from the Laguna dos Patos drainage, southern Brazil, with the descriptions of two new species and the recognition of two species groups

The species of Rineloricaria from the Laguna dos Patos drainage are reviewed. Four species are rediagnosed: R. strigilata, R. cadeae, R. microlepidogaster, and R. longicauda, and two new species are described: R. malabarbai and R. baliola. Rineloricaria malabarbai is distinguished from all other Rineloricaria species except R. maquinensis by its unique abdominal pattern, composed of a large naked area with a single preanal complex of plates and one or two small squarish platelets at the base of pelvic-fin spine and connecting the preanal complex to the lateral abdominal plates, and from R. maquinensis it is distinguished by a longer predorsal length, shorter postanal length, longer abdominal length, broader cleithral width, broader body width at anal-fin origin, deeper head, and shorter maxillary barbel. Rineloricaria baliola is distinguished by its unique color pattern composed of dark, wide bands covering most of the distal one-half of all fins, and by its snout with a roundish naked area, generally reaching to anteriormost pore of infraorbital ramus of sensory canal. The species in Rineloricaria are divided in two phenetic groups, based on general background color pattern, distribution of plates on abdomen, head and snout shape, shape of the naked area at tip of snout, number of lateral body series of plates, and presence of the dorsal-fin spinelet. Species illustrations and a taxonomic key for the Laguna dos Patos drainage are provided.