New nudibranchs to Norway – more knowledge on diversity of sea slugs

Five new species of sea slugs (nudibranchs) have been found in Norwegian coastal waters for the first time. Intensive field work over the last few years have provided new knowledge on distribution and abundance on several species not often observed. These results are a part of our long-going project on diversity of Norwegian nudibranchs we have had running since 1997.

Onchidoris sparsa was one of the species reported as new to the Norwegian fauna in our recent publication. Photo: Torkild Bakken

In the recent paper on nudibranch diversity an account of the total nudibranch fauna of coastal Norwegian waters is give, bringing the number of species known to 87. A total of five species are reported from the Norwegian coast for the first time (Doridoxa ingolfiana, Goniodoris castanea, Onchidoris sparsa, Eubranchus rupium and Proctonotus mucroniferus). In addition 10 species that can be considered rare in Norwegian waters are presented with new information, in some cases with considerable changes to their distribution. These species are Lophodoris danielsseni, Onchidoris depressa, Palio nothus, Tritonia griegi, Tritonia lineata, Hero formosa, Janolus cristatus, Cumanotus beaumonti, Berghia norvegica and Calma glaucoides.

We have previously published, in 2005, an extensive account of presence, distribution abundance of nudibranchs in Norwegian waters. Results presented now are new records found in the period after 2005, and are based on field work after targeting specific habitats. This targeted hunt for new species has resulted successfully by the help from under-water photographers who have taken an interest in nudibranchs. Specific aims and skilled eyes under water have been successful. Due to this we conclude that sampling effort and contributed skills by specialists in collecting at poorly sampled areas is key factors for great success to gain new knowledge of biological diversity.


Evertsen J, Bakken T. 2013. Diversity of Norwegian sea slugs (Nudibranchia): new species to Norwegian coastal waters and new data on distribution of rare species. Fauna norvegica 32: 45-52. DOI: 10.5324/fn.v32i0.1576

Evertsen J, Bakken T. 2005. Nudibranch diversity (Heterobranchia, Gastropoda) along the coast of Norway. Fauna norvegica 25: 1-37.


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