The DIVA-1 (2000), DIVA-2 (2005) and BIOZAIRE (2001, 2003) expeditions to abyssal zones of three ocean basins (Angola, Cape and Guinea) in the SE Atlantic have yielded more than 23,000 specimens or fragments of Polychaeta. Most of the thirteen collecting areas were sampled with an Agassiz trawl, an epibenthic sledge and repeated box corer and multicorer hauls at depths between 3945 and 5672 m. Among the 47 families found, the best-represented were Acrocirridae, Ampharetidae, Chrysopetalidae, Cirratulidae, Hesionidae, Paraonidae, Spionidae and Sabellidae, whereas Alciopidae, Aphroditidae, Cossuridae, Pholoidae, Sternaspidae, Tomopteridae and Typhloscolecidae were rarely found. The present work generally deals with the taxa in Phyllodocida; the remaining groups are planned to be treated in future publications. The material was examined for morphological and partially for molecular characters (18S rDNA, 16S rDNA, COI, ITS1, ITS2); phylogenetic reconstructions were performed using maximum likelihood and parsimony. The following new taxa and names and other changes to nomenclature are proposed. Family Amphinomidae: Bathychloeia balloniformis sp. nov.; Chrysopetalidae: Dysponetus hesionides sp. nov., Dysponetus profundus sp. nov., Pseudodysponetus fragmentosus gen. et sp. nov.; Glyceridae: Glycera diva sp. nov., Glycera southeastatlantica sp. nov.; Hesionidae: Gyptis incisa sp. nov., Nereimyra auripalpa sp. nov., Sirsoe hessleri (Blake, 1991) comb. nov.; Lacydoniidae: Lacydonia elongata Hartmann-Schroder & Rosenfeldt, 1992 syn. nov. of L. papillata Uschakov, 1958; Nereididae: Profundilycastis Hartmann-Schroder, 1977 syn. nov. of Rullierinereis Pettibone, 1971, Ruillerinereis profundus (Hartman, 1965) comb. nov.; Phyllodocidae: Eulalia meteorensis sp. nov., Eumida angolensis sp. nov., Pseudomystides bathysiphonicola (Hartmann-Schroder, 1983) comb. nov., Pseudomystides brevicirra sp. nov., Pseudomystides rarica (Uschakov, 1958) comb. nov., Pterocirrus remus sp. nov.; Sphaerodoridae: Sphaerephesia regularis sp. nov., Sphaerodoropsis longianalpapilla sp. nov., Sphaerodoropsis inacrotubercula sp. nov., Sphaerodoropsis protuberanca sp. nov. and Sphaerodoropsis rosehipiformis sp. nov.; Syllidae: Guillermogonita abyssicola gen. et sp. nov. Identification keys to the encountered families of Polychaeta as well as to the species within each family are presented, where applicable. For the new and many previously established species, detailed morphological descriptions are given and the respective geographic distribution is discussed.
