AN INTRANUCLEAR MICROSPORIDIAN IN LUMPFISH CYCLOPTERUS-LUMPUS

Chronic mortalities in lumpfish Cyclopterus lumpus raised in a saltwat er recirculation system were associated with the presence of an intran uclear microsporidian. Morphologic changes were characterized by infil tration of lymphocyte-like cells predominantly in the renal interstiti um and also in the spleen, liver, gills, stomach, pyloric caecae, hear t, ovary and mesenteric fat. Affected cell nuclei contained 1 to more than 6 spherical to oval eosinophilic bodies which stained poorly with hematoxylin and eosin and Giemsa. Ultrastructurally, spores were ovoi d (2.1 x 1.0 mum) with a polar tube with 11 turns. The morphology of t hese spores place them in the genus Enterocytozoon. These spores resem ble E. salmonis in salmonids, and Microsporidia rhabdophilia in the ro dlet cells of salmonids.