Pseudolithoxus is a genus of suckermouth armored catfishes with five described species from the basins of the Orinoco, Casiquiare and upper Rio Negro in Venezuela.

[1] Additionally, a possibly undescribed species is known from the Trombetas and Nhamundá rivers in Brazil.

[5] The genus is characterized by evertible cheek plates, a very dorsoventrally flattened body, extremely hypertrophied odontodes (integumentary teeth) on elongated pectoral spines and along the snout margin, and 3 rows of plates on the caudal peduncle.

P. dumus has a colour pattern consisting of black spots on the head and anterior part of body, while P. tigris has a colour pattern consisting of brown and tan bars on the head and anterior part of body.

The caudal fin is weakly forked, with the lower lobe longer than the upper.