Two new species of Gyrodactylus (Gyrodactylidae) are described from Corydoras paleatus (Jenyns) and Corydoras ehrhardti Steindachner (Callichthyidae) of Rio Piraquara, Municipality of Piraquara, near Curitiba, Paraná, Brazil: Gyrodactylus anisopharynx sp. n. and Gyrodactylus samirae sp. n. These species are unique among the known Neotropical species of Gyrodactylus by the combination of several characters. Gyrodactylus anisopharynx is characterised by having hooks with point evenly curved, toe moderately pointed, round convex heel, straight sloping shelf, superficial bar with anterolateral projections and male copulatory organ armed with two rows of spinelets. Two variants of G. anisopharynx, of distinct pharynx size, are recognised: forma "large-pharynx" and forma "small-pharynx". Gyrodactylus samirae is characterised by having hook with straight shaft, short slightly recurved point, truncate toe, trapezoidal heel, shelf slightly concave, orthogonal to shaft; anchors with relatively short superficial root; superficial bar with extremities lightly expanded; and male copulatory organ armed with two rows of spinelets. Paragyrodactyloides superbus (Szidat, 1973) is redescribed and transferred to Gyrodactylus based on examination of type and new specimens. Features previously considered as diagnostic for the genus are misinterpretations or primitive characters for Gyrodactylus spp.