Stylommatophora

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Stylommatophora
Temporal range: Cretaceous–Recent
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Superorder: Eupulmonata
Order: Stylommatophora
A. Schmidt, 1855
Diversity[1][2]
about 20,500 species
Cornu aspersum (common garden snail)

Stylommatophora is an order[3] 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.[4]

Stylommatophora are known from the Cretaceous period up to the present day.[5] A molecular clock estimate puts the origin of the crown group also to the Cretaceous.[6]

2017 taxonomy[edit]

The most up-to-date formal classification of Stylommatophora is that of Bouchet et al. (2017).[3] Continuously updated information may be found at MolluscaBase.[7] The 2017 system already becomes obsolete in some parts due to new phylogenetic studies.

Rhytidoidea is apparently not a monophyletic group, but rather a collection of lineages from the southern hemisphere with unresolved relationships.[8]

suborder Achatinina [“Achatinoid Clade”]

suborder Scolodontina

suborder Helicina [“Non-Achatinoid Clade”]

2005 taxonomy[edit]

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.[9] 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.

clade Elasmognatha

clade Orthurethra

informal group Sigmurethra

"limacoid clade" (within the Sigmurethra)

(not in limacoid clade, but is within the Sigmurethra)

Cepaea hortensis, within the Helicoidea.
An individual of Trochulus hispidus, a stylommatophoran land snail in the family Hygromiidae within the Helicoidea.

Previous taxonomy[citation needed][edit]

References[edit]

Wikimedia Commons has media related to Stylommatophora.
Wikispecies has information related to Stylommatophora.
  1. ^ Solem A. (1978). Classification of the land Mollusca. In: Fretter V. & Peake J. (eds). Pulmonates, Vol. 2A. London, Academic Press, 49–97.
  2. ^ Sutcharit C., Naggs F., Wade C. M., Fontanilla I. & Panha S. (2010). "The new family Diapheridae, a new species of Diaphera Albers from Thailand, and the position of the Diapheridae within a molecular phylogeny of the Streptaxoidea (Pulmonata: Stylommatophora)". Zoological Journal of the Linnean Society 160: 1-16. doi:10.1111/j.1096-3642.2009.00598.x.
  3. ^ a b c Philippe 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.
  4. ^ Dayrat, B; Tillier, S (2002-07-29). "Evolutionary relationships of euthyneuran gastropods (Mollusca): a cladistic re-evaluation of morphological characters". Zoological Journal of the Linnean Society. 135 (4): 403–470. doi:10.1046/j.1096-3642.2002.00018.x.
  5. ^ (in Czech) Pek I., Vašíček Z., Roček Z., Hajn. V. & Mikuláš R. (1996). Základy zoopaleontologie. Olomouc, 264 pp., ISBN 80-7067-599-3.
  6. ^ Jörger, Katharina M; Stöger, Isabella; Kano, Yasunori; Fukuda, Hiroshi; Knebelsberger, Thomas; Schrödl, Michael (2010). "On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia". BMC Evolutionary Biology. 10 (1): 323. Bibcode:2010BMCEE..10..323J. doi:10.1186/1471-2148-10-323. ISSN 1471-2148. PMC 3087543. PMID 20973994.
  7. ^ "Molluscabase". molluscabase.org. Retrieved 2023-08-23.
  8. ^ a b c d e Salvador, Rodrigo B.; Silva, Fernanda S.; Cavallari, Daniel C.; Köhler, Frank; Slapcinsky, John; Breure, Abraham S. H. (2023-07-26). Zhang, Feng (ed.). "Molecular phylogeny of the Orthalicoidea land snails: Further support and surprises". PLOS ONE. 18 (7): e0288533. Bibcode:2023PLoSO..1888533S. doi:10.1371/journal.pone.0288533. ISSN 1932-6203. PMC 10370776. PMID 37494326.
  9. ^ Bouchet, Philippe; Rocroi, Jean-Pierre; Frýda, Jiří; Hausdorf, Bernhard; Ponder, Winston; Waldés, Ángel; Warén, Anders (2005). "Classification and Nomenclator of Gastropod Families". Malacologia. 47: 1–397.
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