Bryconops rheorubrum (Characiformes: Iguanodectidae), new species from the Rio Xingu Rapids, Brazil

A new species of Bryconops is described from the rio Xingu Basin, Brazil, that differs from all congeners by the following combination of characters: predorsal scales 8–9, perforated scales in the lateral line 43–45, and pigmentation pattern composed of wide silvery midlateral band on body, hyaline dorsal and anal fins (in alcohol), and dark blotch on distal half of dorsal caudal-fin lobe. The new species shares with members of the subgenus Bryconops maxillary relatively short, edentulous or with one conical tooth, and gill rakers without ossified denticles. The middle and lower Xingu support a remarkable diversity of Bryconops composed of at least nine species-level taxa; comments on their local distributions and habitats are provided, as well as a key to their identification.