Based on a census of the polychaete fauna of the Socotra Archipelago in the Indian Ocean we report here new findings on the genus Syllis Savigny in Lamarck, 1818. These ten species are newly recorded from this area: Syllis alternata Moore, 1908; Syllis bouvieri Gravier, 1900; Syllis broomensis (Hartmann-Schröder, 1979); Syllis compacta Gravier, 1900; Syllis crassicirrata (Treadwell, 1925); Syllis gerlachi (Hartmann-Schröder, 1960); Syllis hyalina Grube, 1863; Syllis lutea (Hartmann-Schröder, 1960); Syllis schulzi (Hartmann-Schröder, 1960); Syllis ypsiloides Aguado, San Martín Ten Hove, 2008. Additionally, Syllis qamhiyn sp. nov. is described as a new species, characterized by its conspicuously thick and short dorsal cirri filled with a gelatinous substance and reduced number of compound chaetae from medium to posterior parapodia, with enlarged shafts and short blades which become almost unidentate and do not fuse with shafts. Following an examination of the holotype of S. bouvieri, its status as a valid species and not as synonym of Syllis prolifera Krohn, 1852, as considered by some authors (see Licher 1999) is confirmed, and a redescription is included.
Keywords: Annelida, Syllis qamhiyn sp. nov., Syllis bouvieri, redescription, new records, taxonomy, morphology.