Morphological and Molecular Characterization of Metacercaria of Tylodelphys (Digenea: Diplostomidae) from the Piscine Host, Mystus tengara from India.

The diversity and taxonomy of diplostomids infecting freshwater fishes of the Indian region are predominantly poorly known. Yet compared to other trematodes, identification and discrimination of diplostomid metacercaria are difficult using morphology and site of infection. The present study provides the first molecular study of a Tylodelphys sp. from India. Specimens of Tylodelphys were collected from the vitreous humor of the eyes and from the brains of siluriform fish, Mystus tengara (Siluriformes: Bagridae) from Hastinapur, Meerut (U.P.), India. Taxonomic studies were performed on the basis of morphological, morphometrical, and molecular analysis. The dissimilarities in morphological and sites of infection between 2 forms of Tylodelphys, designated as Tylodelphys sp. 1 and Tylodelphys sp. 2, suggested that the forms were different species but, after performing molecular analysis, we conclude that despite morphological differences both morphotypes are conspecific.