A new species of whiptail catfish Rineloricaria (Siluriformes: Loricariidae) from Macaé and São João river basins, southeastern Brazil

Abstract A new species of Rineloricaria from the São João and Macaé river basins in Rio de Janeiro State, southeastern Brazil is described. The new species is distinguished from most of its congeners by possessing of five series of lateral plates below the dorsal fin; mid-dorsal series consisting of four or five keeled plates extending posteriorly beyond the origin of the dorsal fin; pectoral girdle covered by plates; snout tip with naked area not reaching most anterior pore of infraorbital ramus of sensory canal; dorsal-fin spinelet present. The new species differs from R. zawadzkii, the most similar and geographically closest species, by having mid-ventral and lateral abdominal plates in contact (vs. separated by skin), the dorsal fin with a dark brown terminal band not reaching the edge, with inconspicuous dark dots along the lower edge (vs. band reaching the edge), and the caudal fin with a diffuse distal band with variegated white spots (vs. a well-defined distal band). The genetic distance based on cytochrome c oxidase I between the new species and the closest congeners supports its validity. The current distribution of the new species in the São João and Macaé basins is consistent with paleo-drainage connections influenced by sea-level fluctuations.