Pseudancistrus can be separated from the Corymbophanini and the Hypostomini by
having hypertrophied odontodes on the cheek; from most of the Rhinelepini by having an
adipose fin and a dorsal flap of the iris and from Pogonopoma wertheimeri by having few
or no plates on the abdomen (vs. abdomen fully plated); and from the Pterygoplichthini by
lacking an enlarged, respiratory stomach and by lacking or nearly lacking plates on the
abdomen (vs. abdomen fully plated in adults), and from Pterygoplichthys by having seven
dorsal-fin rays (vs. nine or more).