Almirón, A. E.-Departamento científico Zoología Vertebrados, Museo de la Plata, Paseo del Bosque, 1900 La Plata, Argentina

Hyphessobrycon wajat, a new species is described from the río Paraná basin in Argentina. This species can be distinguised from its congeners by the following combination of characters: dorsal fin with a black spot, first two dorsal rays with their basal half dusky black, rays 4 to 8 and membranes completely black. Presence of a triangular caudal spot, covering all the base of the caudal fin rays, reaching symmetrically the end of the fin along its central rays. Three to five teeth on the maxilla. Two to four tricuspid teeth on the outer series of the premaxilla. Males lacking hooks on pelvic fins. Low body depth, between 22.8 and 28.8% of standard length