Barreleye Macropinna sp. (Argentiniformes, Opisthoproctidae) from the Miocene of Sakhalin Island, Russia

The first fossil spookfish (Argentiniformes: Opisthoproctidae) is described from deposits of the middle-upper Miocene Kurasi Formation of Sakhalin Island, Russia. The fossil is placed in the family Opisthoproctidae because of the posterior position of its dorsal fin, along with a very small mouth and very long pelvic fin. It is referred further to the genus Macropinna, based on the placement of the anterior margin of the anal fin under the posterior part of dorsal fin, and a close correspondence in vertebra and fin ray counts and body proportions with the only living species, Macropinna microstomaChapman, 1939. The great similarity between fossil and Recent barreleyes suggests that this Miocene form is a representative of the Recent species or a stem member of M. microstoma.