Basommatophora was a term that was previously used as a taxonomic informal group, a group of

snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...

s within the informal group Pulmonata, the air-breathing slugs and snails. According to the

taxonomy of the Gastropoda (Bouchet & Rocroi, 2005) The taxonomy of the Gastropoda as it was revised in 2005 by Philippe Bouchet and Jean-Pierre Rocroi is a system for the scientific classification of gastropod mollusks (Gastropods are a taxonomic class of animals which consists of snails and sl ...

, whenever

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

has not been tested, or where a traditional

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

of gastropods has now been discovered to be

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

, the term "group" or "informal group" was used. Basommatophora are known from the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

to the

Recent The Holocene () is the current geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Qu ...

periods.(in Czech) Pek I., Vašíček Z., Roček Z., Hajn. V. & Mikuláš R.: ''Základy zoopaleontologie''. - Olomouc, 1996. 264 pp., . Most of the families in this suborder are air-breathing freshwater snails. The three most abundant families in terms of number of species are, the Lymnaeidae (pond snails), the Planorbidae (ramshorn snails) and the Physidae (pouch or bubble snails). These are found in ponds, creeks, ditches, and shallow lakes nearly worldwide. The

Siphonariidae Siphonariidae, also known as false limpets, are a taxonomic family of small to medium-sized air-breathing sea snails, marine and brackish water pulmonate gastropod molluscs. __TOC__ Shell description Empty siphonariid limpet shells can be di ...

on the other hand are unusual in that they have secondarily returned to the sea, and are now sea snails,

limpet Limpets are a group of aquatic snails with a conical gastropod shell, shell shape (patelliform) and a strong, muscular foot. This general category of conical shell is known as "patelliform" (dish-shaped). Existing within the class Gastropoda, ...

-like marine gastropods which live in the rocky

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

but which still breathe air and become active at low tide. The single species in the family Amphibolidae is archaic and retains an operculum. It lives at such a high tidal level that it could perhaps be considered semi-terrestrial. Members of the family Chilinidae are confined to temperate parts of South America, and the Latiidae are limpet-like and confined to New Zealand. Basommatophorans are characterized by having their eyes located at the base of their non-retractile tentacles, rather than at the tips, as in the true land snails Stylommatophora. The majority of basommatophorans have shells that are thin, translucent, and relatively colorless, and all except Amphibola lack an operculum.

Taxonomy

1997 taxonomy

In the older taxonomy of the Gastropoda (Ponder & Lindberg, 1997) the suborder Basommatophora consisted of the families : *

Acroloxidae Acroloxidae, commonly known as river limpets, are a Taxonomy (biology), taxonomic family of very small, freshwater snails, Aquatic animal, aquatic pulmonate gastropod limpet-like mollusks with a simple flattened conical gastropod shell, shell in ...

Thiele, 1931 * Amphibolidae J. E. Gray, 1840 - only one species '' Amphibola crenata'' * Ancylidae * Carychiidae Jeffreys, 1830 * Chilinidae * Lancidae * Latiidae *

Lymnaeidae Lymnaeidae, common name the pond snails, is a Taxonomy (biology), taxonomic family (biology), family of small to large air-breathing freshwater snails, Aquatic animal, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila (cl ...

Rafinesque, 1815 * Otinidae H. Adams & A. Adams, 1855 * Physidae Fitzinger, 1833 *

Planorbidae Planorbidae, common name the ramshorn snails or ram's horn snails, is a family (biology), family of air-breathing freshwater snails, Aquatic animal, aquatic pulmonate gastropod Mollusca, molluscs. Unlike most molluscs, the blood of ram's horn sn ...

Rafinesque, 1815 *

J. E. Gray, 1840 *

Trimusculidae ''Trimusculus'' is a genus of medium-sized air-breathing sea snails or false limpets, marine pulmonate gastropod molluscs in the family Trimusculidae. ''Trimusculus'' is the only genus in the family Trimusculidae. Trimusculidae, the button sn ...

Zilch, 1959

2005 taxonomy

The informal group Basommatophora contains the following superfamilies and the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Hygrophila (according to the

Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005) The taxonomy of the Gastropoda as it was revised in 2005 by Philippe Bouchet and Jean-Pierre Rocroi is a system for the scientific classification of gastropod mollusks (Gastropods are a taxonomic class of animals which consists of snails and sl ...

): *Superfamily Amphiboloidea Gray, 1840 **Family Amphibolidae Gray, 1840 *Superfamily Siphonarioidea Gray, 1827 **Family

Gray, 1827 ** † Family Acroreiidae Cossmann, 1893 ; Clade Hygrophila *Superfamily Chilinoidea Dall, 1870 **Family Chilinidae Dall, 1870 **Family Latiidae Hutton, 1882 *Superfamily Acroloxoidea Thiele, 1931 **Family

Thiele, 1931 *Superfamily Lymnaeoidea Rafinesque, 1815 **Family

Rafinesque, 1815 *Superfamily Planorboidea Rafinesque, 1815 **Family

Rafinesque, 1815 **Family Physidae Fitzinger, 1833 The family Ancylidae has been reduced in the new taxonomy to the status of tribe Ancylini

Rafinesque Constantine Samuel Rafinesque-Schmaltz (; 22 October 178318 September 1840) was a French early 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ult ...

, 1815 of the subfamily Planorbinae

, 1815 of the family

, 1815. The family Carychiidae has been reduced in this taxonomy to the status of subfamily Carychiinae Jeffreys, 1830 of the family Ellobiidae L. Pfeiffer, 1854 (1822). The family Lancidae has been reduced in this taxonomy to the status of subfamily Lancinae Hannibal, 1814 of the family

, 1815.

2010 taxonomy

More recently, the Basommatophora was found to be

, and so Jörger et al. (2010)Jörger K. M., Stöger I., Kano Y., Fukuda H., Knebelsberger T. & Schrödl M. (2010). "On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia". ''

BMC Evolutionary Biology ''BMC Ecology and Evolution'' (since January 2021), previously ''BMC Evolutionary Biology'' (2001–2020), is a peer-reviewed open access scientific journal covering all fields of evolutionary biology, including phylogenetics and palaeontology ...

'' 10: 323. . moved its three members, the (superfamily Siphonarioidea, superfamily Amphiboloidea, and clade Hygrophila) into a new taxon,

Panpulmonata Panpulmonata is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura. Panpulmonata was established as a new taxon by Jörger et al. in October 2010. The older name "Pulmonata" referred to a group of euth ...

References

{{Authority control Obsolete gastropod taxa Carboniferous first appearances