D actylogyrus kolodynensis sp. n. (Platyhelminthes: Monogenea) infecting gills of Osteobrama cotio (Hamilton, 1822) (Cypriniformes: Cyprinidae) from India.

Dactylogyrus kolodynensis, a new monogenean parasite species, is described from Osteobrama cotio (Cyprinidae) collected from Lawngtlai (Mizoram) and Lucknow (Uttar Pradesh), India, using morphological examination and sequencing of partial 28S rRNA gene. The new species is morphologically characterized and distinguished from closely related congeners by a combination of the following characters: copulatory tube a loose coil of one complete clockwise ring, jaw-shaped accessory piece comprising variable sheathes enclosing and guiding the copulatory tube, and sclerotized vaginal tube, with a terminal flower-bud-shaped vaginal pore. The molecular analyses of specimens of D. kolodynensis collected from two different localities using 28S rRNA gene showed identical genotype that did not match any of the known sequences in GenBank, confirming our initial morphological identification. Dactylogyrus cotius, a sympatric species on the gills of O. cotio, is regarded as a species inquirenda because of its poor description. This is the first report of a monogenean species from Mizoram, in northeast India, bringing the total number of Dactylogyrus species in India to 57. © Indian Society for Parasitology 2022.