In a study of the oligochaete fauna and their actinosporean parasites in three lakes in Algonquin Park, Canada, a novel form of raabeia-type actinosporean was observed in a single specimen of Uncinais uncinata (∅ersted) (Naididae). This form differs from those previously described in its small size, and by having caudal processes that gradually widen and terminate with a single prominent branch.