Characidium heirmostigmata new species is described from the rio Ivaí drainage, upper rio Paraná basin, Paraná State, Brazil. The new species is diagnosed among its congeners by the possession of eight to 11 incomplete oblique dark bars on the body sides, extending upwards and downwards from the lateral line, independently of the eight or nine dorsal transverse bars usually present in species of Characidium. The new species is similar to Characidium serrano from the upper rio Uruguay basin, but differs by meristic and morphometric traits.
Characidiinae; rio Ivaí basin; Neotropical; Systematics; South American darters
