STUDIES ON THE LIFE-HISTORY OF ALLOCREADIUM ALLONEOTENICUM SP. NOV. (ALLOCREADIIDAETREMTODA)

¹ Marine Biological Laboratory, Woods Hole, Mass.

Allocreadium alloneotenicum sp. nov. is described from the haemocoel of Limnéphilus sp., caddis fly larvae, from Cape Cod, Massachusetts. The life-cycle is demonstrated both in natural and experimental infections. The normal clam host is Pisidium abditum. Miracidia hatch in the debris from dead larvae or after ingestion and passage in the feces of the snail, Aplexa hypnorum. The process of miracidial peneration was observed. Secretions from the apical gland are histolytic in action, facilitating penetration, while the "penetration" glands produce the cuticula of the sporocyst. Sporocysts give rise to one generation of mother rediae which in turn liberate daughter rediae. Daughter rediae give rise to ophthalmoxiphidiocercariae and also produce occasional rediae. The cercariae penetrate caddis fly larvae (as many as 25 of them being found in natural infections). They mature in the haemocoel and a single worm was found to have laid 1200 eggs. Experimental infections of fish with infected caddis fly larvae were negative.