Two new species of Characidium (Characiformes: Crenuchidae) from Paraguay and Xingu River basins, State of Mato Grosso, Brazil

Characidium nupelia, new species, is described from the upper Rio Paraguay basin, and C. xavante, new species, from the upper Rio Xingu basin, State of Mato Grosso, Brazil. The two species comprise a group diagnosed by a high number (12-18) of dark vertical bars on the body, each bar having the width of a scale. Characidium nupelia differs from C. xavante by having 12 instead of 10 scales around the caudal peduncle, a narrower interorbital distance, and a deeper caudal peduncle. Both species lack an adipose fin, have an incomplete lateral line, and have a conspicuous dark blotch on the caudal peduncle. Breeding males of the two new species present sexual hooks on some pelvic and pectoral branched fin rays.