Onchimira cavifera

The new genus and species Onchimira cavifera is a remarkable, unique taxon since represents a living missing link (in evolutionary terms) between two large dorid nudibranch groups - Cryptobranchia (i.e. possess gill cavity) and Phanerobranchia (gill cavity absent). Internal characters of Onchimira (including presence of the well-defined buccal pump medially fully banded with the peripheral muscle and narrow radula with differentiated first lateral teeth) unequivocally can be considered as characteristic features of the phanerobranch family Onchidorididae. On the contrary, well-defined gill cavity with closable over the gill edge of Onchimira cavifera is a typical cryptobranch feature not reported for prima facie "phanerobranch" onchidoridid before. The gill patterns and cavities of the Onchimira cavifera and cryptobranch dorids are essentially similar and their indepedent evolution is hardly plausible. The discovery of Onchimira thus is an important evidence for reduction of the gill cavity in course of the dorid evolution, contrary to the current dominated views considering phanerobranch condition as a most ancestral dorid feature. This important discovery was made by group of Russian scientists from Moscow and Petropavlovsk-Kamchatsky during an expedition in 2008 year to Pacific coast of Kamchatka (Russia). Potential range of Onchimira cavifera may includes Komandorskie (Commander) Islands and Kurile Islands.