"P. genibarbis" reaches a length of SL. They are a large, bulky Loricariid. The armor plates along the side of the fish are thick, are keeled, and encase the whole body. The adipose fin is not present. Like other members of Rhinelepini, they do not have the omega iris that is typical in most species of Loricariids. In Iquitos, Peru, it is known as "carachama sin costilla", which actually means "Loricariid without ribs"; this refers to the trait that it shares with other Rhinelepini catfish that do not have ribs past the sixth vertebra.