Revision of Diplocirrus Haase, 1915, including Bradiella Rullier, 1965, and Diversibranchius Buzhinskaja, 1993 (Polychaeta, Flabelligeridae).

Diplocirrus Haase, 1915, includes flabelligerids having cylindrical to club-shaped bodies, with cirriform papillae, multiarticulate chaetae in both parapodial rami, 8 branchial filaments of two types (thick and rarely lamellate, or cirriform), gonopodial lobes in chaetigers 5 or 6, or multiple gonopores along some anterior chaetigers. Bradiella Rullier, 1965, has included only the type species: Bradiella branchiata Rullier, 1965, described from Eastern Australia. The original description has been overlooked and it lacked enough details on branchial and chaetal features. Diversibranchius Buzhinskaja, 1993, with Diplocirrus nicolaji Buzhinskaja, 1994, as the type species, was introduced for a similar species from the Japan Sea. These two monotypic genera share the same morphologic features with Diplocirrus, and are herein regarded as its junior synonyms. As herein redefined, Diplocirrus includes, besides its type species, Diplocirrus glaucus (Malmgren, 1867)from Scandinavia : Diplocirrus branchiatus (Rullier, 1965), comb. n. from Queensland, Australia, Diplocirrus capensis Day, 1961 from South Africa, Diplocirrus erythroporus Gallardo, 1968 from Vietnam, Diplocirrus hirsutus (Hansen, 1882) from Arctic and subarctic regions, Diplocirrus incognitus Darbyshire & Mackie, 2009 from South Africa, Diplocirrus kudenovisp. n. from off Western Mexico, Diplocirrus longisetosus (von Marenzeller, 1890) restricted to the Bering Sea, Diplocirrus micans Fauchald, 1972 from deep water off Oregon and Western Mexico, Diplocirrus nicolaji (Buzhinskaja, 1994), comb. n. from the Japan Sea, Diplocirrus normani (McIntosh, 1908), comb. n. from Scandinavia, Diplocirrus octobranchus (Hartman, 1965), comb. n. from off New England, and Diplocirrus stopbowitzi Darbyshire & Mackie, 2009 from the Irish Sea.