Description of Apistogramma helkeri sp. n., a new geophagine dwarf cichlid (Teleostei: Cichlidae) from the lower río Cuao (Orinoco drainage) in Venezuela

Apistogramma helkeri sp. n. is described from the drainage of the lower río Cuao in the Estado Amazonas of Venezuela. It is most similar to Apistogramma hongsloi Kullander, 1979, but differs from this species by its colouration and the shape of its dorsal fin. It can be distinguished from all the other described Apistogramma species by the following combination of characters: caudal fin rounded, hyaline and immaculate; dorsal fin lappets short, truncate, without extension or prolongation; caudal spot large, vertically extended; lateral band chainlike or running in a zigzag to 7th bar, not reaching caudal fin or caudal spot; upper pectoral spot present; three distinct abdominal stripes.