During a research on gills ectoparasites of callichthyids fishes from the Peruvian Amazonia, the following new monogenoideans species were recovered: Philocorydoras maltain. sp. from Corydoras splendens (Castelnau) and Brochis multiradiatus (Orcés, V.); Philocorydoras beleniensisn. sp. from C. ambiacus (Cope) and C. agassizii (Steindachner) and Philocorydoras alcantarain. sp. from C. virginiae (Burgess). All new species described herein are mainly differentiated from their congeners based on the morphology of the copulatory complex. In P. maltain. sp. the cirrus corresponds to a very thin curved and slightly sclerotized tube, with an inflated and distally narrow base; the accessory piece is sclerotized, curved in the anterior portion, sickle-shaped and with the terminal portion slightly bent. In P. beleniensisn. sp. the cirrus corresponds to a slightly curved sclerotized robust tube with its base folded back ending in three finger-like projections; the accessory piece is sclerotized, cobra-shaped, distal part with an inwardly-directed curvature. In P. alcantarain. sp. the cirrus corresponds to a sclerotized arched long tube, with sclerotized accessory piece with a bifid termination, curved in its middle portion.