Exitomelita sigynae gen. et sp. nov.: a new amphipod from the Arctic Loki Castle vent field with potential gill ectosymbionts

The newly discovered deep-sea hydrothermal vent field ‘‘Loki’s Castle’’ at 2,350 m depth at 70 N on the Knipovich Ridge north of the island Jan Mayen is the only known black smoker field from the Arctic Ridge system. This vent field holds a unique fauna clearly distinct from vent sites along the Mid-Atlantic Ridge south of Iceland. In addition to numerous maldanid and ampharetid polychaetes one animal of particular interest at this vent site, is a new genus and species of melitid amphipod. This new species is found in cracks and crevices on vent chimneys as well as in areas where diffuse venting is common such as the base of vent chimneys. Here, we present a formal morphological description of this new melitid species and hypothesize about the main form of its nutrition using stable isotope and molecular data