The life cycle of Dollfusinus frontalis, a brachylaimid trematode of small mammals (Insectivora and Rodentia)

Abstract

The life cycle of Dollfusinus frontalis, a parasite of the frontal and nasal sinuses of hedgehogs, dormice and rats on the Mediterranean island of Formentera is elucidated. Cercariogenous sporocysts develop in the digestive gland of two land snails, Trochoidea caroli and T. ebusitana. Free-living cercariae infest another land snail, mainly of the above species, in which unencysted metacercariae develop in the pericardium. Self-infestation of the first intermediate snail host almost always takes place. The sporocyst-bearing snails harbour a much higher number of metacercariae than sporocyst-lacking snails. The two-host life-cycle pattern is almost the general rule on Formentera. Mature metacercariae infest the definitive host when ingested together with the snail. The migration of the metacercariae is direct from the mouth to the nasal sinuses. The successive stages in the several hosts are described. The extreme position of D. frontalis among the family Brachylaimidae is discussed.