Auchenipterus osteomystax (Miranda-Ribeiro, 1918)

Fig. 18

Body elongated; greatest body depth contained 4.0 to 5.9 times in SL; head length 4.5 to 4.8, anal-fin base length 2.2 to 2.5 in SL; snout length 2.3 to 2.6, horizontal orbital diameter 3.2 to 3.5, least interorbital width 2.0 to 2.7 in HL; and orbital diameter 1.7 to 2.3 in interorbital width. Mouth terminal; premaxilla and dentary with several rows of thin teeth. Dorsal fin with 7, pectoral fin with 12 or 13, pelvic fin with 13 or 14 and anal fin with 42-51 rays (Ferraris, Jr., Vari, 1999). Ground color greyish dorsally, whitish ventrally. Dorsal, pelvic and anal fins hyaline; pectoral and caudal fins with distal margins black (Graça, Pavanelli, 2007).

Maximum standard length. 285.0 mm (Graça, Pavanelli, 2007).

Distribution. Río de la Plata, rio Tocantins and lower rio Amazonas basins.

Remarks. Auchenipterus osteomystax is a non-native species from the upper rio Paraná its occurrence can be associated with the filling of the Itaipu Reservoir and the consequent inundation of the Sete Quedas Falls.