Apistogramma ortegai belongs to Apistogramma regani species group, sharing exclusively with A. commbrae (Regan, 1906); A. inconspicua, 1983; and A. linkei, 1985 a tail spot (contiguous caudal spot to bar 7). It can be distinguished from A. commbrae by the absence of vertical stripes on caudal fin (vs. presence); from A. inconspicua by absence of vertical stripes on caudal fin (vs. presence) and by lateral band running into tail spot (vs. lateral band ending in bar 6); from A. linkei by absence of vertical stripes on caudal fin (vs. presence of two vertical stripes posteriorly) and by horizontal abdominal stripes (vs. vertical abdominal stripes). It can be diagnosed from other species with similar general counts, body shape and similar basic melanic color pattern, with exception of the contiguous caudal spot to bar 7: from A. eunotus by having 7-8 predorsal scales (vs. 9-12), 6-8 prepelvic scales (vs. 9-13) and presence of abdominal stripes (vs. absence); from A. cruzi by having 6-8 prepelvic scales (vs. 9-13); from A. aguarico by its dorsal-fin lappets short (vs. five first dorsal-fin lappets elongated) (Ref. 97388).