Marine protozoan epibionts on the copepod Lepeophtheirus salmonis,parasite of the Atlantic salmon

Two species of ciliate suctorian protozoa belonging to the genus Ephelota, E. gemmipara and E. gigantea, were found as epibionts on the marine copepod Lepeophtheirus salmonis (salmon louse), an ectoparasite of marine salmonid fish, including the Atlantic salmon, Salmo salar. Epibionts were distributed over the cephalothoracic shield, genital segment, abdomen and caudal branches of the copepods. Individuals from both species possessed two types of tentacles: long, prehensile, pointed tentacles and short, adhesive, capitate feeding tentacles. Both species contained a highly ramified and lobated macronucleus. E. gemmipara showed a rounded cellular body attached to a stalk possessing longitudinal and transversal striations but lacking a suprastylar extension. E. gigantea had an umbrella‐shaped cellular body significantly larger than in E. gemmipara, the stalk showing only longitudinal striations but possessing a conspicuous suprastylar extension. This is the first time that the presence of ciliate epibionts has been recorded at species level on the copepod Lepeophtheirus salmonis. Statistical data about the distribution of both species on the surface of the copepod are detailed and a new geographical distribution for E. gigantea is proposed.