SYSTEMATICS OF PELAGIC AEOLID NUDIBRANCHS OF THE FAMILY GLAUCIDAE (MOLLUSCA, GASTROPODA)

摘要

Specimens of pelagic aeolid nudibranchs of the family Glaucidae, collected from several localities in the Pacific Ocean, were anatomically examined and described. The comparative study of their external morphology and anatomy revealed that the genera Glaucus and Glaucilla share a number of synapomorphies. Maintenance of two sister monotypic genera is irrelevant and does not provide additional information. Thus, Glaucus is regarded as the single valid genus within the family, with two valid species Glaucus atlanticus Forster, 1777 and Glaucus marginatus Forster, 1777. Glaucus marginatus is reported from the northeastern Pacific for the first time and an aberrant specimen of G. atlanticus, with smooth radular teeth, is described. The presence of a penial spine and a penial gland together and the abnormal cleioproct condition in Glaucus suggests that this taxon could be closely related to Cuthona (Family Tergipedidae) rather than to Facelina and other related groups, as several authors have proposed. However, there is no compelling evidence one way or the other.