Parancistrus Bleeker, 1862

Diagnosis. Parancistrus can be characterized by the presence of a membranous connection between the dorsal and adipose fins, cephalic and body scutes not carinate and a large gill opening. Armbruster (1997) additionally diagnosed the genus based on posterior deflection of the hyomandibula and presence of fleshy folds along the dorsal-fin base of nuptial males. Parancistrus can be further distinguished from Ancistrus and Chaetostoma by having a plated snout and from all other genera of the Ancistrini (sensu Armbruster, 2004), except Baryancistrus, Oligancistrus, and Spectracanthicus, by the connection between dorsal and adipose fins; from Baryancistrus, Oligancistrus, and Spectracanthicus, by the large gill openings.