ИСТИНА

Most species of the family Tergipedidae possess a slender body with simple branches of the digestive gland tending to reduce, sometimes up to single ceras per row. Only few taxa, for instance the type species of the genus Cuthona, C. nana have a relatively broad body and highly branched digestive gland. Most Tergipedidae, with minor exceptions, have the anus in the acleioproctic position, high in the interhepatic space. A notal ridge is not known for tergipedids. The present study examines two tergipedid genera which possess numerous branches of the digestive ducts, an elevated lateral ridge, a posterior anus and other atypical characters for the family Tergipedidae. One of these taxa is a new genus and species from the Murman coast of the Barents Sea (depth 60-300 m). It is characterized by having a wide body, numerous branched rows of the digestive gland ducts and an elevated not al ridge. The radular teeth of the new genus possess unusual clusters of lateral denticles. The other taxon, the Antarctic genus Guyvalvoria Vayssiere, 1906 is revised. Based on new material and the type specimen, the type species of the genus, G. francaisi Vayssiere, 1906 is redescribed. Two new species of the genus Guyvalvoria are described from the Davis Sea and the sub-Antarctic Kerguelen Id. The Antarctic genus Guyvalvoria and sub-Arctic new genus have some similarities in their external appearance, both have numerous branches of the digestive gland and have a tendency to shift the anus caudally. Morphological peculiarities of the new taxa suggest a new interpretation of the head, which differentiates it from the typical head of other aeolids. Transformation of the digestive gland branching pattern within the family is also explored. Both the new genus and Guyvalvoria Vayssiere, 1906 are considered basal within the Tergipedidae.