We used a molecular phylogenetic approach to investigate species delimitation and diversification in the northeastern Atlantic and Mediterranean musseldrills of the Ocinebrina aciculata complex, based on molecular data from topotypical material of many of the nominal taxa. The complex is shown to consist of at least five species: Ocinebrina aciculata (Lamarck, 1822) from the Atlantic and western Mediterranean; O. cf. corallina (Scacchi, 1836) from the central Mediterranean Sea; O. reinai Bonomolo & Crocetta, 2012 from the Tyrrhenian Sea; O. corallinoides Pallary, 1912 from the Gulf of Gabès; and O. aegeensis n. sp. currently known from the Aegean Sea only. The new species is differentiated from the other taxa by very subtle morphological diagnostic features, although it is clearly identified by genetic distance and apomorphic DNA-sequence characters. The identity of Murex corallinus Scacchi, 1836 (type species of Ocinebrina Jousseaume, 1880) could not be defined with certainty, pending genetic comparison of specimens of the ‘large Tyrrhenian morphotype’ (corresponding to the neotype, but not assayed herein) with the assayed ‘small morphotype’.