Stylommatophora is an orderPhilippe Bouchet, Jean-Pierre Rocroi, Bernhard Hausdorf, Andrzej Kaim, Yasunori Kano, Alexander Nützel, Pavel Parkhaev, Michael Schrödl and Ellen E. Strong. 2017. Revised Classification, Nomenclator and Typification of Gastropod and Monoplacophoran Families. Malacologia, 61(1-2): 1-526. of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This taxon includes most land snails and slugs. Stylommatophorans lack an operculum, but some close their shell apertures with temporary "operculum" (epiphragm) made of calcified mucus. They have two pairs of retractile tentacles, the upper pair of which bears eyes on the tentacle tips. All stylommatophorans are hermaphrodites.

The two strong synapomorphies of Stylommatophora are a long pedal gland placed beneath a membrane and two pairs of retractile tentacles.

Stylommatophora are known from the Cretaceous period up to the present day. Pek I., Vašíček Z., Roček Z., Hajn. V. & Mikuláš R. (1996). Základy zoopaleontologie. Olomouc, 264 pp., . A molecular clock estimate puts the origin of the crown group also to the Cretaceous.

Stylommatophora is the most diverse group of terrestrial gastropods, with approximately 22,753 species recognized as of 2024.

2017 taxonomy

The most up-to-date formal classification of Stylommatophora is that of Bouchet et al. (2017). Parts of the 2017 system have become obsolete due to new phylogenetic studies, and continuously updated information may be found at MolluscaBase.

Rhytidoidea is apparently not a monophyletic group, but rather a collection of lineages from the southern hemisphere with unresolved relationships.

Suborder Achatinina ["Achatinoid Clade"]

Superfamily Achatinoidea Swainson, 1840 Achatinidae Swainson, 1840 Aillyidae H. B. Baker, 1955 Ferussaciidae Bourguignat, 1883 Micractaeonidae Schileyko, 1999 Superfamily Streptaxoidea Gray, 1860 Streptaxidae Gray, 1860 Diapheridae Panha & Naggs, 2010

Suborder Scolodontina

Superfamily Scolodontoidea H. B. Baker, 1925 Scolodontidae H. B. Baker, 1925

Suborder Helicina ["Non-Achatinoid Clade"] incertae sedis Superfamily Coelociontoidea Iredale, 1937 Coelociontidae Iredale, 1937 Superfamily Papillodermatoidea Wiktor, Martin & Castillejo, 1990 Papillodermatidae Wiktor, Martin & Castillejo, 1990 Superfamily Plectopyloidea Möllendorff, 1898 Plectopylidae Möllendorff, 1898 Corillidae Pilsbry, 1905 Sculptariidae Degner, 1923 Superfamily Punctoidea Morse, 1864 Punctidae Morse, 1864 Charopidae Hutton, 1884 Cystopeltidae Cockerell, 1891 Discidae Thiele, 1931 Endodontidae Pilsbry, 1895 Helicodiscidae H. B. Baker, 1927 Oreohelicidae Pilsbry, 1939 Superfamily Testacelloidea Gray, 1840 Testacellidae Gray, 1840 Superfamily Urocoptoidea Pilsbry, 1898 Urocoptidae Pilsbry, 1898 Cerionidae Pilsbry, 1901 Epirobiidae F. G. Thompson, 2012 Eucalodiidae P. Fischer & Crosse, 1873 Holospiridae Pilsbry, 1946 Infraorder Succineoidei [= Elasmognatha] Superfamily Succineoidea Beck, 1837 Succineidae Beck, 1837 Superfamily Athoracophoroidea P. Fischer, 1883 Athoracophoridae P. Fischer, 1883 Infraorder Rhytidoidei Superfamily Rhytidoidea Pilsbry, 1893 Rhytididae Pilsbry, 1893 Acavidae Pilsbry, 1895 Caryodidae Conolly, 1915 Clavatoridae Thiele, 1926 Dorcasiidae Connolly, 1915 Macrocyclidae Thiele, 1926 Megomphicidae H. B. Baker, 1930 Odontostomidae Pilsbry & Vanatta, 1898 (according to Salvador et al. 2023, in Bouchet et al. classified in Orthalicoidea) Strophocheilidae Pilsbry, 1902 Infraorder Orthalicoidei Superfamily Orthalicoidea Martens, 1860 Orthalicidae Martens, 1860 Amphibulimidae P. Fischer, 1873 Bothriembryontidae Iredale, 1937 Bulimulidae Tryon, 1867 Cyclodontinidae Salvador & Breure, 2023 (see Salvador et al. 2023) Megaspiridae Pilsbry, 1904 Simpulopsidae Schileyko, 1999 Tomogeridae Jousseaume, 1877 (see Salvador et al. 2023) Infraorder Pupilloidei [= Orthurethra] Superfamily Pupilloidea Turton, 1831 Pupillidae Turton, 1831 Achatinellidae Gulick, 1873 Agardhiellidae Harl & Páll-Gergely, 2017 Amastridae Pilsbry, 1910 Argnidae Hudec, 1965 Azecidae Watson, 1920 Cerastidae Wenz, 1923 Chondrinidae Steenberg, 1925 Cochlicopidae Pilsbry, 1900 Draparnaudiidae Solem, 1962 Enidae B. B. Woodward, 1903 Fauxulidae Harl & Páll-Gergely, 2017 Gastrocoptidae Pilsbry, 1918 Lauriidae Steenberg, 1925 Odontocycladidae Hausdorf, 1996 Orculidae Pilsbry, 1918 Pagodulinidae Pilsbry, 1924 Partulidae Pilsbry, 1900 Pleurodiscidae Wenz, 1923 Pyramidulidae Kennard & B. B. Woodward, 1914 Spelaeoconchidae A. J. Wagner, 1928 (Croatia, Bosnia and Hercegovina) Spelaeodiscidae Steenberg, 1925 Strobilopsidae Wenz, 1915 Truncatellinidae Steenberg, 1925 Valloniidae Morse, 1864 Vertiginidae Fitzinger, 1833 Infraorder Clausilioidei Superfamily Clausilioidea Gray, 1855 Clausiliidae Gray, 1855 † Filholiidae Wenz, 1923 † Palaeostoidae H. Nordsieck, 1986 Infraorder Arionoidei Superfamily Arionoidea Gray, 1840 Arionidae Gray, 1840 Anadenidae Pilsbry, 1948 Ariolimacidae Pilsbry & Vanatta, 1898 Binneyidae Cockerell, 1891 Philomycidae Gray, 1847 Infraorder Limacoidei ["Limacoid Clade"] Superfamily Limacoidea Batsch, 1789 Limacidae Batsch, 1789 Agriolimacidae H. Wagner, 1935 Boettgerillidae Wiktor & I. M. Likharev, 1979 Vitrinidae Fitzinger, 1833 Superfamily Gastrodontoidea Tryon, 1866 Gastrodontidae Tryon, 1866 Oxychilidae Hesse, 1927 Pristilomatidae Cockerell, 1891 Superfamily Parmacelloidea P. Fischer, 1856 Parmacellidae P. Fischer, 1856 Milacidae Ellis, 1926 Trigonochlamydidae Hesse, 1882 Superfamily Zonitoidea Mörch, 1864 Zonitidae Mörch, 1864 superfamily Trochomorphoidea Mörch, 1864 Trochomorphidae Möllendorff, 1890 Chronidae Thiele, 1931 Dyakiidae Gude & B. B. Woodward, 1921 Euconulidae H. B. Baker, 1928 Staffordiidae Thiele, 1931 Superfamily Helicarionoidea Bourguignat, 1877 Helicarionidae Bourguignat, 1877 Ariophantidae Godwin-Austen, 1888 Urocyclidae Simroth, 1889 Infraorder Oleacinoidei Superfamily Oleacinoidea H. Adams & A. Adams, 1855 Oleacinidae H. Adams & A. Adams, 1855 Spiraxidae H. B. Baker, 1939 Superfamily Haplotrematoidea H. B. Baker, 1925 Haplotrematidae H. B. Baker, 1925 Infraorder Helicoidei ["Helicoid Clade"] Superfamily Sagdoidea Pilsbry, 1895 Sagdidae Pilsbry, 1895 Solaropsidae H. Nordsieck, 1986 Zachrysiidae Robinson, Sei & Rosenberg, 2017 Superfamily Helicoidea Rafinesque, 1815 Helicidae Rafinesque, 1815 Cepolidae Ihering, 1909 Labyrinthidae Borrero, Sei, Robinson & Rosenberg, 2017 Thysanophoridae Pilsbry, 1926 Camaenidae Pilsbry, 1895 Polygyridae Pilsbry, 1895 Elonidae Gittenberger, 1977 Trissexodontidae H. Nordsieck, 1987 Helicodontidae Kobelt, 1904 Sphincterochilidae Zilch, 1960 Geomitridae C. Boettger, 1909 Canariellidae Schileyko, 1991 Hygromiidae Tryon, 1866 Pleurodontidae Ihering, 1912 Trichodiscinidae H. Nordsieck, 1987 Xanthonychidae Strebel & Pfeffer, 1879

2005 taxonomy According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) based on evolutionary ancestry, Stylommatophora is a clade in the clade Eupulmonata within informal group Pulmonata. It uses unranked clades for taxa above the rank of superfamily (replacing the ranks suborder, order, superorder and subclass) and the traditional Linnaean approach for all taxa below the rank of superfamily.

The clade Stylommatophora contains the subclades Elasmognatha, Orthurethra and the informal group Sigmurethra. The term "informal group" has been used to indicate whenever monophyly has not been tested, or where a traditional taxon of gastropods has now been discovered to be paraphyletic or polyphyletic.

Previous taxonomy

References