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.
2007 The Plankton Society of Japan, The Japanese Association of Benthology