Abstract
The male or cryptoniscus larva of a new epicaridean parasite, Cironiscus dahli gen. et sp. nov., is described and illustrated. The systematic affinity of Cironiscus is discussed, and it is concluded that the genus belongs to the family Cabiropsidae within the Cryptoniscinae. The parasite was found on Cirolana borealis and Cirolana microphthalma, mainly from Scandinavian waters. The geographical distribution is mapped, and some notes on host-parasite relations are given. The host Cirolana borealis is reported for the first time from the Baltic.