Pseudancistrus corantijniensis is distinguished from non-derived Pseudancistrus and other Ancistrini by the presence of hypertrophied odontodes along the snout in males as well as in females and quite

early in ontogeny. Pseudancistrus corantijniensis is diagnosed from derived Pseudancistrus on the basis of coloration: whitish spots very small, crowded and faint (especially in preserved specimens) on the snout to the posterior border of the eyes and the anterior border of the cleithrum, becoming abruptly larger (at least 1 mm in diameter even in young specimens), more spaced and more visible on the posterior part of the head. Large whitish spots continue along the body with a slight and gradual increase in size posteriorly. A single large whitish spot is generally present on each dorso-lateral plate posterior to the pelvic-fins. Pseudancistrus barbatus and P. depressus have smaller whitish spots covering the body and the spots increase slightly

and gradually in size from snout to caudal peduncle rather than displaying an abrupt spot size reduction posterior to the eyes as in P. corantijniensis. In P. nigrescens, the whitish spots increase gradually in size from the

snout to caudal peduncle, yet they become bigger and hazier than in the other derived Pseudancistrus. In the latter species, larger spots are often not round and can cover more than one plate.