The genus Clio is a taxonomic group of small floating sea snails, pelagic marine opisthobranch gastropod mollusks, the sole genus belonging to the family Cliidae
All species in this genus are characterised by a bilaterally symmetric, straight or adapically dorso-ventrally slightly curved shell, with an elliptical to triangular transverse section; protoconch clearly separated, globular or elliptical, frequently with a spine at the tip. Subgenera are used for some species (e.g. Clio s.str., Balantium Bellardi, 1872, Bellardiclio Janssen, 2004), but most species cannot yet be assigned to one of these.
Numerous fossil species have been described.
Recognised extant species are:
Clio andreae (Boas, 1886)
Distribution : north Atlantic, bathypelagic species.
Clio antarctica Dall, 1908
Clio bartletti van der Spoel, 1978
Distribution: central Atlantic (Pleistocene fossil).
Clio campylura (Tesch, 1948)
Clio chaptalii J. E. Gray, 1850
Distribution : tropical, circumglobal.
Clio convexa convexa (Boas, 1886)
Distribution: tropical, Indo-Pacific
Clio convexa cyphosa Rampal, 2002
Distribution: Red Sea and Gulf of Aden.
Clio cuspidata (Bosc, 1802)
Distribution : tropical/subtropical, circumglobal.
† Clio oblonga Rampal, 1996
Clio orthotheca (Tesch, 1904)
Clio piatkowskii van der Spoel, Schalk & Bleeker, 1992
Distribution: Antarctic.
Clio polita Pelseneer, 1888
Clio pyramidata Linnaeus, 1767
Distribution : north Atlantic
Height : to over 20 mm.
Formae:
forma excisa van der Spoel, 1963
forma lanceolata Lesueur, 1813 (tropical/subtropical, circumglobal)
forma martensi (Pfeiffer, 1880) ??
forma sulcata (Pfeffer, 1879)
The true status of these formae has to be evaluated, they might be real formae, subspecies, or even species.
Clio recurva (Children, 1823)
Distribution : tropical-subtropical, circumglobal (bathypelagic species)**
Height: to over 30 mm
Clio sulcata (Pfeffer, 1879)
Species brought into synonymy
Clio australis: synonym of Clione limacina australis (Bruguière, 1792)
Clio borealis (Pallas, 1774): synonym of Clione limacina (Phipps, 1774)
Clio helicina Phipps, 1774: synonym of Limacina helicina (Phipps, 1774)
