First report of parasitic isopod Nerocila orbignyi (Cymothoidae) from India with its molecular characterization.

The present report provides the first material evidence of  Nerocila orbignyi  (Guérin-Méneville, 1832) collected from two different landing centres of the Chilika lagoon, thus claiming the first report of this parasite from India. One of the specimens was recorded from the host fish species  Plotosus canius  Hamilton 1822, constituting the first host record for this isopod. A key for the identification of  N. orbignyi among its congeners is also provided .  Molecular characterization of Cytochrome C Oxidase I (COI) gene of  N. orbignyi  was based on one specimen submitted for the first time to the NCBI database. This parasite is differentiated from the other available sequences of its related congeners retrieved from the NCBI and BOLD database by 26-34% in the Kimura 2 Parameter (K2P) distance and belongs to a separate cluster in Maximum likelihood (ML) tree analysis.