History of the Clio pyramidata-complex (Mollusca, Gastropoda, Euthecosomata, Cliidae) in the Atlantic Ocean, restoring its original concept

An extensive overview of the historical use of the genus Clio and its type species Clio pyramidata Linné, 1767 (described from the Caribbean: Jamaica) during the last two and a half centuries demonstrates the current incorrect use of the species name and the junior synonymy of the taxon Hyalea lanceolata Lesueur, 1813 (described from the Mediterranean). The latter taxon was incorrectly considered to be a shell-morphologically different form of C. pyramidata. A neotype is designated for C. pyramidata from the original type locality to stabilise nomenclature. We examined the relationship of two shell forms of that species, viz. the form with straight carinae or shell sides (occurring in the northern Atlantic Ocean and so far considered to represent typical C. pyramidata) and the (neo)typical form with strongly concave carinae (occurring in the (sub)tropical Atlantic, inclusive of the Caribbean and Mediterranean) currently indicated as forma or subspecies lanceolata Lesueur, 1813. Based on combined morphological and genetic analyses of specimens from the Atlantic Ocean and the Caribbean we found that there are intermediates between the two shell forms and that they have different, but overlapping distributions. Moreover, there was no molecular evidence to separate the two forms as distinct species. Hence, we consider the name C. pyramidata appropriate for the different shell forms within this taxon. For the form with straight carinae the name angusta Boas, 1886, is available, but may be applied at subspecific rank only. A lectotype for angusta is selected, and a type species is designated for Flabellulum Bellardi, 1873.