Clio
Clio recurva (specimen at the Smithsonian Institution)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Clade:	Euopisthobranchia
Order:	Pteropoda
Suborder:	Euthecosomata
Superfamily:	Cavolinioidea
Family:	Cliidae
Genus:	Clio Linnaeus, 1767
Type species
Clio pyramidata Linnaeus, 1767
Synonyms
Balantium Children, 1823 † Balantium (Flabellulum) Bellardi, 1873 † Balantium (Poculina) Bellardi, 1873 (invalid: junior homonym of...) † Chaduma Korobkov, 1966 Cleodora Peron & Lesueur, 1810 Clio (Balantium) Children, 1823 Clio (Bellardiclio) A.W. Janssen, 2004 Clio (Clio) Linnaeus, 1767 · alternate representation † Clio (Nudiclio) Korobkov, 1966 Euclio Bonnevie, 1913 · unaccepted Proclio Hubendick, 1951

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^[1]

All species within this genus exhibit a bilaterally symmetrical shell that is either straight or slightly curved dorso-ventrally towards the apex. The shell cross-section is elliptical to triangular. The protoconch is distinct and globular or elliptical, often bearing a spine at its tip.

While some species are classified within subgenera (e.g., Clio s.str., Balantium Bellardi, 1872, Bellardiclio Janssen, 2004), the majority of species remain unassigned to one of these.

Numerous fossil species have been described.

Recognised extant species are:

• † Clio aichinoi Checchia-Rispoli, 1921
• Clio andreae (Boas, 1886)
  • Distribution : north Atlantic, bathypelagic species.
• Clio bartletti van der Spoel, 1978 ^{[citation needed]}
  • Distribution: central Atlantic (Pleistocene fossil).
• † Clio bellardii Audenino, 1895
• † CLio berglundorum Squires, 1989
• † Clio blinkae A. W. Janssen, 1989
• † Clio braidensis (Bellardi, 1873)
• † Clio calix (Bellardi, 1873)
• Clio campylura (Tesch, 1948)
• † Clio carinata Audenino, 1895 †
• † Clio chadumica Korobkov, 1966
• Clio chaptalii J. E. Gray, 1850
  • Distribution : tropical, circumglobal.
• † Clio colina A. W. Janssen & Zorn, 2001
• 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 distefanoi Checchia-Rispoli, 1921
• † Clio fallauxi (Kittl, 1886)
• Clio flabelliforme (Blankenhorn, 1889)
• † Clio gailae Goedert & A. W. Janssen, 2012
• † Clio ghawdexensis A. W. Janssen, 2003
• † Clio giulioi A. W. Janssen, 1995
• † Clio goedertorum Squires, 1989
• † Clio guidottii Simonelli, 1896
• † Clio hataii (H. Noda, 1972)
• † Clio ichishiensis (Shibata, 1983)
• † Clio irenae A. W. Janssen, 1989
• † Clio itoigawai (Shibata, 1983)
• † Clio jacobae A. W. Janssen, 1989
• † Clio kendacensis P. Jung, 1971
• † Clio lavayssei Rutsch, 1934
• † Clio lozoueti A. W. Janssen, 2010
• † Clio lucai A. W. Janssen, 2000
• † Clio merijni A. W. Janssen, 2012
• † Clio multicostata (Bellardi, 1873)
• † Clio nielseni A. W. Janssen, 1990
• † Clio oblonga Rampal, 1996
• † Clio ortheziana (Benoist, 1889)
• Clio orthotheca (Tesch, 1904)
• † Clio pauli A. W. Janssen, 1989
• † Clio pedemontana (C. Mayer, 1868)
• Clio piatkowskii van der Spoel, Schalk & Bleeker, 1992
  • Distribution: Antarctic.
• Clio polita Pelseneer, 1888
• † Clio pulcherrima (Mayer, 1868)
• 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 ricciolii (Calandrelli, 1844)
• † Clio saccoi Checchia-Rispoli, 1921
• † Clio scheelei (Munthe, 1888)
• † Clio shibatai Ujihara, 1996
• † Clio sulcosa (Bellardi, 1873)
• † Clio triplicata Audenino, 1895
• † Clio vasconiensis A. W. Janssen, 2010
• † Clio vilis A. W. Janssen, 2012

Species brought into synonymy

• Clio antarctica Dall, 1908: synonym of Clio pyramidata antarctica Dall, 1908 accepted as Clio pyramidata Linnaeus, 1767 (superseded combination)
• 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)
• Clio sulcata (Pfeffer, 1879): synonym of Clio pyramidata f. sulcata (Pfeffer, 1879) accepted as Clio pyramidata Linnaeus, 1767

• Vaught, K.C. (1989). A classification of the living Mollusca. American Malacologists: Melbourne, FL (USA). ISBN 0-915826-22-4. XII, 195 pp
• Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 180–213
• Willan, R. (2009). Opisthobranchia (Mollusca). In: Gordon, D. (Ed.) (2009). New Zealand Inventory of Biodiversity. Volume One: Kingdom Animalia. 584 pp