Morphological, ultrastructure and molecular characterization of (Acari: Hydrachnida: Unionicolidae) isolated from , West Bengal, India.

spp. is a parasitic aquatic mite known to infect freshwater aquatic organisms, especially the marine and freshwater molluscs and few species of sponges. (Acari: Hydrachnida: Unionicolidae) generally infect the freshwater bivalves of the Genus sp. They are usually facultative in nature and can be parasitic at any stage of their life cycle. They cause damage to the gills of the host which harms their normal respiration process. The present work portraits the morphological characters, ultrastructure and DNA barcoding of its mitochondrial gene Cytochrome Oxidase I (COI)(mtCOI), and its taxonomic position was justified by obtaining a phylogenetic tree. The description regarding its morphological characters, ultrastructure and molecular characterization has been presented here. This paper holds the report of a parasitic aquatic mite for the first time from a gastropod molluscan host (Lamarck, 1882), from Diamond Harbour, South 24 Parganas, West Bengal, India.