The family Oweniidae Rioja, 1917 is a small group of broadly distributed polychaetes whose relationships and position in the annelid tree are still poorly understood. A comprehensive revision of the group with reconsideration of character homologies and terminology under a phylogenetic framework was needed. We investigated the relationships of members of Oweniidae and other polychaetes by performing maximum parsimony analyses of 18 oweniid species of the five recognized genera to date and members of the families Siboglinidae, Sabellidae, Spionidae, Magelonidae, and Chaetopteridae. Phylogenetic hypotheses confirmed the monophyly of Oweniidae and suggested sister-group relationships with Magelonidae, although weakly supported. Analyses also recovered Owenia and Myriowenia as monophyletic and allowed recognition of Myrioglobula as a junior synonym of Myriochele based on the presence of acicular chaetae and the shape of the head. Implied weighting analyses supported these findings and recovered Galathowenia australis as sister group of Myriochele. The presence of acicular chaetae justifies the consideration of this species as belonging to Myriochele. Nomenclatural changes are proposed for those species previously considered as members of Myrioglobula, and these are: Myriochele antarctica comb. nov., Myriochele japonica comb. nov., Myriochele islandica comb. nov., Myriochele malmgreni comb. nov., and Myriochele australis comb. nov. After analyses and definition of generic diagnostic features, other new combinations include Galathowenia eurystoma comb. nov. and Galathowenia haplosoma comb. nov., previously considered as members of Myriochele. Taxonomic revision of Australian collections revealed the presence of Myriochele heruensis Gibbs, 1971, which is herein redescribed, and allowed the description of four new species: Galathowenia annae sp. nov., Galathowenia arafurensis sp. nov., Galathowenia quelis sp. nov., and Myriochele australiensis sp. nov., mostly from the east coast of Australia, in addition to the three recently well-documented species of Owenia. Australian species have been described, illustrated, and compared in detail with similar taxa. Distribution patterns and ecological notes have also been given. Keys to oweniid genera and Australian species are provided.
