First record of a rare species, Polyasterias problematica (Prasinophyceae), in Balsfjord, northern Norway

Abstract

<i>Polyasterias problematica</i> is a poorly investigated prasinophyte species, practically known only from a few, primarily historical studies. Fragmentary information on the species indicates that <i>P. problematica</i> is mainly distributed in the euphotic zone of the Canadian and Russian Arctic, Atlantic Canada, the mid-Atlantic and some European seas. Here, we present the first record of this species in the Balsfjord waters, northern Norway. A detailed morphological description, with line drawings and microscopy-based photographs, as well as information on its up-to-date geographical distribution and possible explanations for its extraordinary scarcity are provided.