Key to species of genus Amatitlania

11a(6a) Circumpeduncular scales modally 15-16; body depth usually greater than 50% of SL, always greater than 48% of SL; stripe from snout to eye usually well defined............................................ 12

11b Circumpeduncular scales modally 17-18; body depth usually less than 48% of SL, always less than 50% of SL; stripe from snout to eye usually diffuse......................................................................... 13

12a(11a) Eye blue, gold-rimmed; modally 2-2.5 scales from lateral line to first dorsal fin ray (Fig. 20); caudal vertebrae modally 15................................................................................ Amatitlania kanna

12b Eye bluish or greenish; modally 1.5 scales from lateral line to first dorsal fin ray (Fig. 21); caudal vertebrae modally 14............................................................................................ Amatitlania siquia

13 a(11b) Fourth bar on side of body Y-shaped (Fig. 19); body depth usually less than 47% of SL, always less than 48% of SL; lower lip often with a caudad projection at dorsal angle; abdominal vertebrae 13 ........................................................................................................... Amatitlania coatepeque

13b Fourth bar on side of body I-shaped (Fig. 18); body depth usually greater than 47% of SL, always greater than 46% of SL; lower lip, normal at angle; abdominal vertebrae 12 .......... ………………… ................................................................................................................ ….. Amatitlania nigrofasciata