Clio (gastropod)

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 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 still need to be assigned to one of these.

Numerous fossil species have been described.

Species
Recognised extant species are:

Formae: The true status of these formae has to be evaluated, they might be real formae, subspecies, or even species.
 * 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.
 * forma excisa van der Spoel, 1963
 * forma lanceolata Lesueur, 1813 (tropical/subtropical, circumglobal)
 * forma martensi (Pfeiffer, 1880) ??
 * forma sulcata (Pfeffer, 1879)
 * 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)