Piggybacking pycnogonids and parasitic narcomedusae on Pandea rubra (Anthomedusae, Pandeidae)

Associations between pycnogonids and the mesopelagic anthomedusan Pandea rubra are reported from two in situ video footage records off the Pacific coast of northern Japan, and from a plankton sample collected in the Weddell Sea (one juvenile of the pycnogonid Pallenopsis (Bathypallenopsis) tritonis). This is the first pelagic record of a pycnogonid in the Southern Ocean and the first record of an association between pycnogonids and a hydroidomedusa at mesopelagic depths. Taxonomic descriptions of both host and associate are given. Two early stages of a parasitic narcomedusa adhered to the medusan subumbrella are also reported. Possible origins for the pycnogonid-medusa association are postulated.