Inhabitant or visitor? Unexpected finding of Aglaophenia (Cnidaria, Hydrozoa) in Antarctic waters

Abstract

Benthic hydrozoans are one of the most speciose and characteristic taxa from the Antarctic region, with a high number of endemic species, but diversity at the genus level is low and some families with world wide distribution are unrepresented. This is the case of the family Aglaopheniidae. A new species to science of the genus Aglaophenia Lamouroux has been found in the eastern end of the Weddell Sea, at depths of 65–116 m, within the material obtained by the German Antarctic expedition ANT XV/3. This finding constitutes a new record for the Weddell Sea fauna, the first evidence of the genus for the Polar Regions, and even the family Aglaopheniidae from Antarctic waters. The material has been accurately examined and described. Literature concerning the species of Aglaophenia from the sub-Antarctic and other close areas has been reviewed and, as a result, a checklist of 20 species, with their corresponding distribution, is given. The material examined does not agree with any of the species and therefore it is described as a new species. Some possible scenarios for the presence of an aglaopheniid in Antarctic waters are discussed (e.g. alien species, relict, global climate change, microhabitat).