Three new species of Jainus (Monogenoidea: Dactylogyridae) from the gills of Triportheus angulatus (Characiformes: Triportheidae) collected in the Peruvian Amazonia.

Three new species of Jainus Mizelle, Kritzky & Crane, 1968, are described parasitizing the gill filaments of Triportheus angulatus (Spix & Agassiz) (Characiformes: Triportheidae), an omnivorous fish endemic to the Amazon River basin. Jainus iquitensis n. sp. is characterized by the morphology of the vagina, which is bell-shaped, with a canal as a sclerotized tube and the morphology of hook pair VII, which in the new species presents an inflated base, a characteristic not observed in other congeners. Jainus loretoensis n. sp. is unique among Jainus species due to the morphology of its Y-shaped ventral anchors, with an arrow-shaped superficial root and a finger-shaped deep root. Jainus sardinae n. sp. is characterized by presenting a slender, small J-shaped tube with a sigmoid accessory piece and a ventral anchor that is Y-shaped, with inconspicuous finger-shaped deep root and superficial root with rounded ending with a chin-shaped projection. These findings add three new species to the previously reported two Jainus species from Peru.