The identification of magelonids with mucronate chaetae on chaetiger 9 has long been confused. Until 1977 all corresponding European specimens were erroneously referred to Magelona papillicornis; a Brazilian species. Since then, but without any detailed study, the name M. mirabilis (originally given to a species from Scotland) has been widely employed. However, in recent years, it has become clear that two morphologically similar species coexist in European waters. Magelona mirabilis is redescribed and a neotype designated, and M. johnstoni sp. nov. is formally distinguished. Following re-examination of the other five species present in the region, a dichotomous key and a synoptic table of characters is provided for all seven European species.