It is native to South America, where it occurs in the Tocantins River basin in Brazil.

The species is notably large for a loricariid, reaching 60 cm (23.6 inches) SL.

[2] P. major was described in 2018 by Carine C. Chamon (of the Federal University of Tocantins) and Thiago Costa e Silva on the basis of coloration and morphology.

Its specific epithet derives from Latin and refers to its large size.

[2] It appears in the aquarium trade, where it is usually referred to either as the giant cactus pleco or by its L-number, which is L-186.