A collection of more than 1500 specimens of Syllidae (Annelida, Polychaeta) from sub-Arctic and Boreal regions along the coast of Norway has been studied. We report 32 species, two of them new to science, belonging to the genera Sphaerosyllis Claparède, 1863 and Syllis Savigny in Lamarck, 1818, and 16 new to Norway. Sphaerosyllis tarquei sp. nov. is characterized by having long blades on its compound chaetae and the presence of glands inside the dorsal cirri. Syllis kas sp. nov. was reported, figured and described by Uschakov (1955) as Syllis oerstedi (Malmgren, 1867); however, revision of the types of Chaetosyllis oerstedi reveals that they are sexual stolons of Syllis cornuta Rathke, 1843; this species is characterized by the shape of the spiniger-like chaetae, which are relatively short, distally blunt, with a thin distal spine, and unidentate falcigers some of which have similar spines. We also include descriptions and figures of Parexogone longicirris (Webster & Benedict, 1887) and Syllides longocirrata Ørsted, 1845. Finally we include a key of all reported species in the area.

In a study investigating the composition and spatial and temporal variation of the benthic macrofauna associated to the discharge of domestic sewage off Fortaleza, north-eastern Brazil, a new species of Syllis was found. This new species, S. guidae sp. nov., is characterized by having blades of falcigers with subdistal tooth about same length as distal tooth, but stouter than it, with spines on cutting edge almost reaching the tip of subdistal tooth, blades of falcigers with conspicuous subdistal triangular process and unusually long anal papilla between anal cirri, measuring about one-quarter of their length. Syllis guidae sp. nov., is herein described and compared with the most similar congeners.