<jats:p>Species of dinophycean Amphidomataceae are producers of phycotoxins classified as azaspiracids. We provide the first records of two of their constituent species,<jats:italic>Amphidoma languida</jats:italic>and<jats:italic>Azadinium dexteroporum</jats:italic>, for the Irminger Sea off Iceland. Morphological examination and molecular characterization, including uncorrected mean pairwise distances between sequences of the Internal Transcribed Spacer (ITS), doubtlessly assigned the sub-Arctic strain 2A11 to the reference of<jats:italic>Amphidoma languida</jats:italic>. Strain 2A11 produced AZA-38 and AZA-39, corresponding to the toxin profile described for the type material. The sub-Arctic isolate 1D12 differed significantly in terms of ITS genetic distance (p = 0.04) from a Mediterranean<jats:italic>Azadinium dexteroporum</jats:italic>strain, but our morphological analysis did not reveal any major or stable diagnostic traits between the reference strain of<jats:italic>Azadinium dexteroporum</jats:italic>and the new strain described here. In contrast to the Mediterranean strain of<jats:italic>Azadinium dexteroporum</jats:italic>, the sub-Arctic strain 1D12 did not produce any known azaspiracids. The new records of<jats:italic>Amphidoma languida</jats:italic>and<jats:italic>Azadinium dexteroporum</jats:italic>from the Irminger Sea imply an important range extension of the species, formerly known from the northern and eastern Atlantic (<jats:italic>Amphidoma languida</jats:italic>) and from the Mediterranean area (<jats:italic>Azadinium dexteroporum</jats:italic>) only. Together with three new species of<jats:italic>Azadinium</jats:italic>recently described from the same expedition, the results clearly show that the biodiversity of the Amphidomataceae in the sub-Arctic is remarkably large.</jats:p>