Astyanax keronolepis is distinguished from all other species of Astyanax by the following combination of characters: 9-11 dentary teeth, gradually decreasing in size; high concentration of chromatophores distributed along the scale contour forming a hexagonal pattern, resembling a honeycomb; head heavily covered with tubercles in adults males; midlateral strip expanded anteriorly and tapering posteriorly toward the caudal peduncle; and caudal spot elliptically shaped. In addition, this species differs from most congeners, except from A. taeniatus, A. ribeirae, A. hastatus, A. burgerai, A. giton and A. bahiensis, by its humeral spot shaped like a comma. It can be diagnosed from A. taeniatus by having teeth asymmetrical and with no gap on the dentary symphysis (vs. teeth symmetrical and with a gap on dentary symphysis). It can be differentiated from A. ribeirae, A. hastatus, A. burgerai, A. giton and A. bahiensis by having only one humeral spot (vs. two humeral spots) (Ref. 119398).

Description: Dorsal-fin rays ii, 9; anal-fin rays iii-iv, 18-22; pectoral-fin rays i, 11-13; pelvic-fin rays i-ii, 7-8; horizontal scale rows between lateral line and pelvic-fin origin 4-6 (Ref. 119398).