A new species of Rhamdella Eigenmann & Eigenmann, 1888 (Siluriformes: Heptapteridae) from the coastal basins of southern Brazil

Rhamdella zelimai, new species, is described from the coastal river drainages in northeastern Rio Grande do Sul and southern Santa Catarina States, Brazil. The new species is readily distinguished from its congeners by the hypertrophy of the rictal fold, mainly its lower portion, consisting of a large and fleshy lobe that bends ventrally on itself. The phylogenetic relationships of the new species are assessed and it was recovered as belonging to the clade composed of R. eriarcha (from the laguna dos Patos basin), R. longiuscula (from the rio Uruguai), and R. cainguae (from the lower rio Paraná).