Some remarks on the occurrence and development of philometrid nematodes infecting the white sucker, Catostomus commersoni Lacépède (Pisces: Catostomidae), in Ontario

Abstract

During a study on the parasitofauna of white sucker (Catostomus commersoni) in Laurel Creek, Ontario, three philometrid nematodes were found. Gravid and subgravid females completing the life cycle occurred very infrequently (Philometroides huronensis: 4.3%, Philometroides nodulosa: 1.6%, Philometra kobuleji: 1.1%). In comparison, males and retarded females infected the eyeball and the peritoneum around the swim bladder very often (43.1 and 31.6% in total, respectively). Less frequently, developmental stages were found in the abdominal cavity. Specimens found in the eyeball were identified as belonging to P. nodulosa, while the swim bladder forms could belong to P. huronensis or to P. kobuleji. The eyeball and the peritoneum around the swim bladder are regarded as refuges for retarded forms, where they can survive for more than a year. No evidence was found of a direct cause of retardation.