The tanaidomorphan genera Leptognathioides and Portaratrum from the Benthic
Invertebrates of Icelandic waters (BIOICE), Marine Benthic Fauna of the Faroe
Islands (BIOFAR), and Atlantic Frontier Environmental Network (AFEN)-related
surveys are examined. The diagnosis for Leptognathioides polita is amended and
additional size data are given. A new species, L. biarticulata, is described although the differences from L. polita are slight. It occurs in the bathyal Iceland Basin with a distribution that does not overlap with that of L. polita. A new species of Portaratrum, P. holdichi, is described and the apparent similarities (parallelisms) between this former colletteid genus and the akanthophoreid Chauliopleona are discussed. The distribution and rarity of both genera in the region are analysed, Leptognathioides being more common in the cold-water areas or along the cold– warm interface. Portaratrum holdichi n. sp. is more common and abundant in the Rockall-Biscay region of the NE Atlantic.
