New species of Dactylogyridae Bychowsky, 1933 infecting the gills of Myloplus schomburgkii (Jardine) and Colossoma macropomum (Cuvier) in the Peruvian Amazon.

Four new dactylogyrid species are described, three species (Anacanthorus camposbacae n. sp., Anacanthorus carmenrosae n. sp. and Notozothecium nanayensis n. sp.) from the gills of Myloplus schomburgkii (Jardine), captured in the River Nanay, Iquitos, Peru, and one new species (Mymarothecium iiapensis n. sp.) from the gills of Colossoma macropomum (Cuvier) in a fish pond in Iquitos, Peru. Anacanthorus camposbacae n. sp. differs from its congeners by possessing the accessory piece with a sub-medial branch having tentacle-like extensions. Anacanthorus carmenrosae n. sp. is characterised by possessing a Y-shaped accessory piece. Notozothecium nanayensis n. sp. differs from its congeners by the shape of both anchors and the presence of a short anteromedial triangular process in the ventral bar and by possessing an accessory piece with spoon-shaped proximal end. Mymarothecium iiapensis n. sp. is characterised by presenting a wrench-tool-shaped accessory piece and by possessing both anchors with conspicuous fold on the superficial roots.