Nodular lesions on the fins of winter flounder, Pseudopleuronectes americanus, from Casco Bay, Maine, were identified as lymphocystis disease. Hypertrophied, encapsulated connective tissue cells contained cytoplasmic inclusions composed of icosahedral virus particles. The winter flounder is a new host for lymphocystis disease and is the second flatfish in the western North Atlantic to have the disease.
