THE SYSTEMATIC POSITION OF THE GENUS NUCELLA (PROSOBRANCHIA, MURICIDAE, OCENEBRINAE)

The muricid genus Nucella Roding, 1798 has commonly been placed in Tha idinae Jousseaume, 1888 (Prosobranchia: Muricidae). The Thaidinae (sen su Kool, 1989) is monophyletic with and thus synonymous with Rapaninae Gray, 1853 (Kool, 1993, in press). Comparative anatomical investigati ons of the type species of Nucella Roding, 1798 (Buccinum filosum Gmel in, 1791 [=Nucella lapillus (Linnaeus, 1758)]) and of Thais Roding, 17 98 (Murex fucus Gmelin, 1791 [=Thais nodosa (Linnaeus, 1758)]) as well as other rapanines have revealed that inclusion of Nucella in Rapanin ae would result in polyphyletic groups (Kool, 1989; 1993, in press). S tudies of the anatomy, radula, protoconch, shell ultrastructure, and o perculum of the type species of Nucella, Ocenebra Gray, 1847 (Murex er inaceus Linnaeus, 1758 [=Ocenebra erinacea]) (Ocenebrinae Cossmann, 19 03), and Trophon Montfort, 1810 (Murex magellanicus Gmelin, 1791 [=Tro phon geversianus (Pallas, 1774)]) (Trophoninae Cossmann, 1903), indica te that Nucella has close affinities with Ocenebrinae and Trophoninae. Based on cladistic analyses, it is here proposed that Nucella be plac ed in Ocenebrinae. Results further reveal that the distinctions betwee n Ocenebrinae and Trophoninae are less clear than previously accepted.