We describe two new species of Guianacara from the Guiana Shield of eastern Venezuela. Guianacara stergiosi, new species and G. cuyunii, new species belong in the subgenus Guianacara and thus are distinguished from G. oelemariensis (subgenus Oelemaria) by the possession of two (vs. one) supraneurals and produced lappets on the dorsal-fin spines. Guianacara stergiosi can be distinguished from all other species in the subgenus Guianacara by the possession of a round midlateral spot almost entirely below the upper lateral line, forming the darkest area in the midlateral bar. In other species with a midlateral spot, the spot is oval-shaped and located on and above the upper lateral line (G. sphenozona), or on and below the upper lateral line (G. owroewefi). In Guianacara stergiosi the midlateral bar progressively fades into a midlateral spot in all but small juvenile specimens, distinguishing the species from G. geayi, which generally has a complete midlateral bar; in G. geayi the midlateral bar can be reduced to a midlateral spot in large specimens, in which case the black coloration of the anterior dorsal-fin lappets is lost, whereas it is maintained in G. stergiosi at all sizes. Guianacara stergiosi is known from the Caroní and lower Aro River drainages, and from the upper Caura River basin upstream of the Para rapids. Guianacara cuyunii is distinguished from all other species in the subgenus by the possession of a thinner midlateral bar (about three scales wide vs. four scales wide) that is generally not replaced by a midlateral spot, except in very large specimens, by having a pectoral fin that does not reach the anal fin, and for being the only known species without a grayish branchiostegal membrane. Guianacara cuyunii is known from the upper Cuyuní River drainage in Venezuela, including its major tributaries. It is currently unknown whether the distribution of this species spans the lower reaches of the Cuyuní and Essequibo drainages.

Describimos dos especies nuevas de Guianacara del Escudo Guayanés en el este de Venezuela. Guianacara stergiosi sp. nov. y G. cuyunii sp. nov. pertenecen al subgénero Guianacara y por lo tanto se distinguen de G. oelemariensis (subgénero Oelemaria) por poseer dos (en lugar de uno) supraneurales y prolongaciones de las membranas de las espinas de la aleta dorsal. Guianacara stergiosi se distingue de las otras especies en el subgénero Guianacara por poseer una mancha medio-lateral redonda, localizada casi enteramente bajo la linea lateral superior formando el área más oscura de la banda medio-lateral. En otras especies con mancha medio-lateral, la mancha es de forma oval y está localizada sobre y arriba de la linea lateral superior (G. sphenozona), o sobre y abajo de la linea lateral superior (G. owroewefi). En Guianacara stergiosi la banda medio-lateral desaparece progresivamente hasta tornarse en una mancha medio-lateral en todos los especímenes excepto en pequeños juveniles, distinguién