Hypopygus ortegai is diagnosed from congeners by the following combination of characters: the dorsal rami of intermittent branch of anterior lateral line nerve not visible (versus visible in remain species), the total number of anal-fin rays (137-147 versus 102–135 in H. hoedemani, H. lepturus, and H. minissimus; 155–174 in H. cryptogenes), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), the head length (12.6–13.9% of LEA versus 13.2–15.3 in H. nijsseni), the distance at the nape (11.0–12.5% of LEA versus 12.5–13.8 in H. nijsseni), the distance from the anus to the anal-fin ray (6.5–9.5% of LEA versus 10.0–12.0 in H. neblinae), and the head length (12.6–13.9% of LEA versus 13.2–22.9 in H. isbruckeri) (Ref. 88778).