Contents lists available at ScienceDirect Veterinary Parasitology journal homepage: www.elsevier.com/locate/vetpar Short communication Morphological and molecular analyses of Tylodelphys spp. metacercaria (Trematoda: Diplostomidae) from the vitreous humour of two freshwater fish species, Channa gachua (Ham.) and Puntius sophore (Ham.) Anshu Chaudhary ⁎ , Shivi Gupta, Richa Tripathi, Hridaya S. Singh Molecular Taxonomy Laboratory, Department of Zoology, Chaudhary Charan Singh University, Meerut, U.P., 250004, India ARTICLE INFO Keywords: Tylodelphys spp Molecular characterization SEM Fish Meerut India ABSTRACT Trematodes of family Diplostomatidae consists of a large and diverse group of parasites which have larval stages that are very important pathogens of wild and cultured freshwater fishes worldwide, can cause serious impacts. Our understanding of the diplostomids diversity, though, remains deficient and limited especially in India. In the present study, the morphology and molecular characterization of Tylodelphys spp. from the vitreous humour of eye, collected from two economically important food fish, dwarf snakehead Channa gachua (Perciformes: Channidae) and pool barb Puntius sophore (Cypriniformes: Cyprinidae) were described from Bijnor and Meerut, Uttar Pradesh (U.P.), India respectively. Tylodelphys spp. were characterized morphologically by light micro- scopy and SEM observations. Partial sequences of the ribosomal ITS1-5.8S-ITS2 gene cluster were also used for molecular identification of the species. Combined morphological and molecular analyses revealed the presence of three species of Tylodelphys: Tylodelphys sp. CG from C. gachua and Tylodelphys sp. PS 1, Tylodelphys sp. PS 2 from P. sophore respectively. This study demonstrated that molecular diversity of Tylodelphys spp. in Meerut, UP, India that may contribute to our knowledge of the diagnosis and taxonomy of diplostomids in fish. 1. Introduction Tylodelphys Diesing, 1850 is a genus that widely distributed in freshwater systems. Species of this genus have three hosts in their life cycle, intermediate hosts, including lymnaeid snails and fish while the definitive hosts are fish eating birds. The main frequently encountered stages of their life cycle are the metacercariae that found unencysted in the cranial cavity of brains and eyes of freshwater fish (Flores, 1997; Musiba and Nkwengulila, 2006; Chibwana and Nkwengulila, 2010; Chibwana et al., 2015; Otachi et al., 2015; Blasco-Costa et al., 2016; García-Varela et al., 2016). Metacercaria stage of Tylodelphys may exert serious impacts on wild and cultured fish populations, causes eye cat- aracts and disruption of the brain tissue that finally lead to the mor- tality in fish (Chappell, 1995; Sandland and Goater, 2000). There are many species of Tylodelphys metacercaria, about > 20 described within India under genera Diplostomulum Hughes, 1929 but some synonymies with Tylodelphys (Pandey and Agrawal, 2013; Blasco-Costa et al., 2016). Moreover, data on the species of diplostomids from India is hindered due to limited studies on their taxonomy. The Indian species of di- plostomids described morphologically and still their identification problems remains because of lack of molecular data. However, the difficulty in the identification and discrimination of diplostomids can be overcome by the use of molecular techniques. The molecular tools have established an important and efficient approach in the taxonomic identification of diplostomids worldwide (Locke et al., 2010a; Georgieva et al., 2013; Blasco-Costa et al., 2014, 2016; Otachi et al., 2014; Pérez-del-Olmo et al., 2014; Chibwana et al., 2015; García-Varela et al., 2016). Recent molecular studies using ri- bosomal ITS1-5.8S-ITS2 gene sequences have been successfully char- acterized the diplostomids species which were previously identified based only on morphology (Locke et al., 2010b; Chibwana et al., 2013; Blasco-Costa et al., 2014, 2016; Pérez-del-Olmo et al., 2014). Never- theless, our knowledge of the Tylodelphys spp. diversity in India is quite limited, because of deficiencies in molecular data from the inter- mediate/definitive hosts. In this study, we used the morphology, scanning electron micro- scopy and ribosomal ITS1-5.8S-ITS2 gene cluster sequences to char- acterize the Tylodelphys species diversity of freshwater fish in India. http://dx.doi.org/10.1016/j.vetpar.2017.07.016 Received 18 January 2017; Received in revised form 6 June 2017; Accepted 19 July 2017 ⁎ Corresponding author. E-mail address: anshu8282@rediffmail.com (A. Chaudhary). Veterinary Parasitology 244 (2017) 64–70 0304-4017/ © 2017 Elsevier B.V. All rights reserved. MARK