Over 100 specimens of Desmoscolex were found in samples from Yonge Reef, Lizard Island and Nymphe Island (Great Barrier Reef, Australia). In the present paper 4 new species are described: D. brevisetosus sp.n., characterized by the absence of subventral setae on the 2nd main ring and the presence of short fubdorsal setae on the 16th main ring: D. dimorphus sp.n. characterized by the presence of sexual dimorphism (absence of subventral setae on the 14th main ring, short subdorsal setae on the 16th main ring and smaller aphids in females);D. geraerti sp. n. and D. nymphianus sp. n. with the typical setal pattern and elongated laterally shifted subdorsal setae on the 13th, 16th and 17th main ring but the former sp characterized by large bipartite amphids, cephalated spicules and trough-shaped gubernaculum; the latter sp by the smaller rounded amphids with their posterior margin coinciding with that of the amphidial pore and by the short straight spicules.