The relationships of the Mediterranean trochid gastropods 'Monodonta' mutabilis (Philippi, 1846) and 'Gibbula' richardi (Payraudeau, 1826)

The Mediterranean trochid gastropods currently known as Monodonta mutabilis (Philippi, 1846) and Gibbula richardi (Payraudeau, 1826) are shown, on both morphological and electrophoretic grounds, to be sibling species, and therefore congeneric. The generic name Phorcus Risso, 1826 should be used for these species, which may be more closely related to the Mediterranean Trochocochlea species than to other species classified in Gibbula. The oldest appropriate genus-group name for the Mediterranean species currently classified as Monodonta (M. articulata, M. turbinata) is Trochocochlea Morch, 1852. The earliest type species designation for Osilinus Philippi, 1847 is that of Trochus constrictus Lamarck, 1822 by Herrmannsen (1847), which would make Osilinus a valid senior synonym of the widely used name Austrocochlea Fischer, 1885 and not of Trochocochlea as commonly accepted. A ruling of the International Commission on Zoological Nomenclature will be sought for the case.