Pseudancistrus is a genus of armored suckermouth catfish in the family Loricariidae, part of the broad pleco group, native to the Guiana Shield river systems of Brazil, Suriname, Guyana, Venezuela, and French Guiana. The 15 species in the atlas run from roughly 3 in up to about 10 in and share the typical bottom-dwelling pleco body plan: a flattened, bony-plated body and a ventral suckermouth used to graze algae and biofilm from rock and wood, usually in the faster, well-oxygenated water of rapids and rocky stream stretches rather than sluggish lowland rivers. The genus name reflects tufts of bristle-like odontodes many species carry on the head and cheeks, most obvious on breeding males, echoed in common names like bearded catfish (Pseudancistrus barbatus) and flattened bearded pleco (P. depressus).
Other named species include the Kukenan Pseudancistrus (P. coquenani), tiger-cheek Pseudancistrus (P. genisetiger), bighead pleco (P. megacephalus), headspotted stream pleco (P. nigrescens), and starry pleco (P. sidereus), and a few of these turn up in the specialist pleco hobby, kept much like other Guiana Shield loricariids with strong flow, high oxygen, and driftwood to graze and rasp. Conservation data are patchy, with several species still unassessed, but none currently carry a threatened status, and most of the genus remains better known to ichthyologists surveying Guiana Shield streams than to the wider aquarium trade.