Apistogramma erythrura sp.n. is described from the drainage of the lower río Mamoré in the province of Beni in Bolivia. It is most similar to Apistogramma trifasciata, but differs from this species by the complete absence of any abdominal markings below the lateral band. It can be distinguished from all the other described Apistogramma species by the following combination of characters: only two postlacrymal infraorbital lateralis canal pores, fi ve dentary lateralis canal pores, a broad lateral band with even borders that widens posteriorly to a height of at least two and a half scales and extends into the caudal fin without a caudal spot. Adult males usually with a partly or even completely bright red colouration of their rounded caudal fin, extremely produced anterior dorsal-fin lappets and prolonged pelvic-fin fi laments reaching the posterior end of the analfin base.