Heterobranchia (Mollusca, Gastropoda) from northern Norway, with notes on ecology and distribution

During a diving expedition through northern Norway, a total of 25 heterobranchiate taxa were collected, and additional data on distribution and ecology were given. Cumanotus beaumonti and Flabellina borealis are recorded for the first time since Odhner (1907), (1922) on the Norwegian coast, and the distribution of eight heterobranch taxa were re-evaluated. By using SCUBA diving as a sampling method, it is proved that the diversity and distribution of heterobranchs is poorly known in northern Norwegian waters, as the results show that large quantities of specimens, as well as a significant number of taxa, are found at each locality. The significance of diving for studying heterobranchs is emphasized. Apart from new records of heterobranchs and enhanced knowledge of biodiversity and biogeography of this group in northern Norway, this paper presents previous published literature where heterobranch taxa are mentioned for northern Norway.