Actinosporean infections in oligochaetes in a river system in southwest Ireland with descriptions of three new forms.

Abstract

Sediment samples were collected in April, June and August 1998 from a river in southwest Ireland. A total of 1,836 oligochaete specimens were collected from these sediments, and examined for actinosporean infections. Actinosporean-infected oligochaetes have been determined, symptoms and course of infection have been considered and the spores released from them have been described. Spore characteristics for each actinosporean were defined and the prevalence of infection in each oligochaete species was also determined. The overall prevalence of infection with actinosporeans within the oligochaete sample was approximately 2%. Seven types were distinguished, belonging to echinactinomyxon, aurantiactinomyxon and neoactinomyxum forms, from Tubifex ignotus, Lumbriculus variegatus and Limnodrilus hoffmeisteri, and compared with actinosporean types previously reported in the literature. Three of these forms have not been previously described, while the other 4 are morphologically and morphometrically similar to known forms. These actinosporeans may be stages in myxozoan life cycles.