Included in this report are new distribution records and descriptions of 44 species of Polynoidae distributed between two subfamilies: Lepidonotinae, with Hermenia verruculosa Grube and Lepidonopsis humilis (Augener); and Harmothoiniae, with Subadyte pellucida (Ehlers), and three species and one new combination of Hololepidella Willey. The study includes a replacement of Malmgrenia McIntosh, 1874 (= indeterminable) with Malmgreniella Hartman, 1967, emended, with a redescription of M. dicirra Hartman, 1967, the type species, and a review and revision of the species that have been referred to Malmgrenia, resulting in 13 new combinations (with 2 new synonyms) and 19 new species of Malmgreniella. In addition, three new genera are added, including Paragattyana, for P. micropoides (Augener), new combination, and P. intesi, new species; Rullieriella, for R. monoechinata (Rullier), new combination, with synonym Parahalosydna chryostictus Hutchings and Rainer; and Wilsoniella for W. furcosetosa (Loshamn), new combination. Most of the species show a more or less close association with other invertebrates, including echinoderms (ophiuroids, spatangoid echinoids, synaptid holothurians), coelenterates (hydrocorals), and other polychaetes (arenicolids, terebellids, and chaetopterids).
