A New Cercaria of the Subfamily Gymnophallmae (Trematoda: Digenea) developing in a unique ‘Parthenita’ in Littorina saxatilis (Olivi)

Abstract

A ‘PARTHENITA’ containing furcocerous and tailless stages of a gymnophalline cercaria was found in the hæmolymph spaces of the digestive gland, gonad and gonoduct of the gastropod Littorina saxatilis. The unique feature of this ‘parthenita’ is that it has the same essential structure as the cercariæ which it produces. It is not yet possible to decide whether this ‘parthenita’ is, in fact, a cercaria possessing the kind of multiplication more usually associated with a redia or sporocyst; or whether it is a sporocyst or redia with a structure similar to a cercaria. Until this is decided the word ‘parthenita’ will be used here to indicate an analogy with the more usual redia or sporocyst found in digenetic trematodes.