Redescription of the arctic-boreal species Calathura brachiata (Stimpson, 1853) (Isopoda, Anthuridea, Paranthuridae)

Calathura brachiata (Stimpson, 1853) has been found in the North Atlantic, north of Iceland and northeast of Greenland; 750 specimens have been investigated. Although this species is quite large and widely distributed, the identification was complicated by the fact that the synonymy with Calathura norvegica (Sars, 1872) and Anthura arctica (Heller, 1875) had not yet been satisfactorily resolved. Moreover, the descriptions of these species were either incomplete, or it was difficult to recognize the species from the illustrations. We therefore present a complete redescription of manca stages 2 and 3, as well as of an adult female, on the basis of our material from the North Atlantic, together with a redescription of an adult male based on museum material.