Megaleporinus

1. Lateral line with 39 to 40 (rarely 41) pored scales ........ ............................................................................ M. piavussu

1’. Lateral line with 41 to 44 pored scales .......................... 2

2. Mouth always subterminal, its cleft at horizontal through ventral margin of orbit or slightly below; three black blotches on flank, equally rounded; dark-brown transverse bars on flank usually persistent in large specimens; longest anal-fn ray more than twice the length of the last ray........ ......................................................................... M. obtusidens

2’. Mouth usually terminal, its cleft above horizontal through ventral margin of orbit; three black blotches on flank, first blotch vertically elongated, and remaining rounded; dark-brown transverse bars on flank usually not persistent in large specimens; longest anal-fn ray less than twice the length of the last ray ................. M. macrocephalus