Life cycle of the seabird digenean Gymnophallus minor (Gymnophallidae) in the Arctic.

Gymnophallidae is one of the digenean families featuring bivalves as first intermediate hosts. However, the exact bivalve host species remain unknown for most members of this family. Gymnophallids have been one of the targets in our continuous efforts to reveal the diversity of digeneans in the higher north. Here, we focus on Gymnophallus minor, which we found in eiders from various locations in the Arctic and sub-Arctic. Sexual adults (maritae) of G. minor can be easily identified because they have a distinctive character: the roughly equal size of the pharynx and the ventral sucker. We also matched them, using DNA markers, with the intramolluscan stages (sporocysts, cercariae, and metacercariae) from the bivalve Liocyma fluctuosa collected on Spitsbergen. Taken together, we compile the first data on the life cycle of G. minor and discuss them in the context of other gymnophallids.