Fig. 25

Body deep; greatest body depth contained 4.2 to 4.9 and caudal peduncle depth 8.3 to 9.6 times in SL; head length 3.4 to 3.9, predorsal distance 2.2 to 2.5, dorsal-fin spine length 2.2 to 2.7, pectoral-fin spine length 3.1 to 3.3 and adiposefin spine length 8.9 to 9.7, and caudal-peduncle length 3.3 to 3.8 times in SL; snout length 1.5 to 1.6, horizontal orbital diameter 5.2 to 8.6 and least interorbital width 1.6 to 2.0 in HL. Mouth inferior; premaxilla with 19-36 and dentary with 17-37 teeth. Mid-lateral series with 29-31 plates, predorsal series with 3 plates, and dorsal-fin base series with 8 plates. Dorsal fin with I,11-14, pectoral fin with I,6, pelvic fin with I,5 and anal fin with 5 rays. Ground color dark-grey; body and fins with white or light-beige blotches.

Maximum standard length. 500.0 mm.

Distribution. Río de la Plata basin.

Remarks. Pterygoplichthys ambrosettii was identified as P. anisitsi by Graça, Pavanelli (2007). Ferraris, Jr. (2007), in the checklist of the catfishes, proposed the new synonym. Pterygoplichthys ambrosettii is a non-native species from the upper rio Paraná, and its occurrence can be associated with the filling of the Itaipu Reservoir and the consequent inundation of the Sete Quedas Falls, or with the aquarium trade (Júlio Júnior et al., 2009).