Four valid species of the genus Gymnogonos are known at this point of investigations: G. crassicornis (northern Atlantic and the Arctic Seas); G. obvolutus (northern Atlantic and the Arctic Seas); G. ameriensis (circumantarctic distribution) and the new species G. pacificus (northern Pacific). Other species, such as Corymorpha antarctica (Pfeffer, 1889) and Tubularia cingulata (Vanhöffen, 1910) from the southern hemisphere are recognized as ‘species inquirendae’. New descriptions and taxonomic discussions of the known Gymnogonos species have been proposed. This genus has a typical bipolar distribution in the classical meaning of this term. This genus origin may rise from tropical Corymorphidae by neoteny in the period of glacial cooling.
