Studies on the morphology of Uronema marinum Dujardin (Ciliatea: Uronematidae) with a description of the histopathology of the infection in marine fishes

Abstract

Abstract. A normally free‐living hymenostomatid ciliate was found to be the cause of heavy infections of gills, viscera and body muscle in Atlantic and Pacific marine fishes kept in the New York Aquarium. Of special interest is the fact that the parasites, usually with food vacuoles filled with blood cells and cellular debris, caused extensive damage to the body muscle; the other infected organs showed no characteristic tissue reactions. The immediate cause of death is attributed to the exceptional load of the parasite on the gills, thus interfering with normal respiratory function.The ciliate, isolated from a recent outbreak, is described in detail, and shows many characteristics of Uronema marinum Dujardin, a species that has been reported as free‐living in salt water; the form reported here differs from the type and other members included in this species, by the presence of less than three rows of bipolar meridians. This facultative parasite is described in detail and compared with other genera.