During taxonomic studies on the Trichobranchidae housed at the Australian Museum, Sydney morphological characters of specimens were found to serve taxonomists on four taxonomic levels – family, genus, species and specimen level. The number of neuropodial uncini per torus and abdominal segments, long considered holding information for species determination, proved to be highly variable within species. Characters found to be consistent within species were e.g.,the position of nephridial papillae, shape of branchiae and chaetae, and the development of anterior segments and lateral lappets. Also, staining in methyl green resulted in a clear pattern without intraspecific variability in most cases and is since considered a helpful tool for identification of Trichobranchidae. In this study an overview of morphological characters of Trichobranchidae and their information for taxonomy is given based on the trichobranchid collection of the Australian Museum. Additionally, description of a new species Terebellides jitu sp. nov., formerly treated as a variation of Terebellides narribri, is given. The description of T. narribri is revised.
Key words: Southern hemisphere, Annelida, Terebellida, Terebellides jitu sp. nov., Terebellides narribri