Lower Heterobranchia, also known as the Allogastropoda, is a group of rather specialized, highly evolved

sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

s and

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s, marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusks Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The num ...

within the subclass

Heterobranchia Heterobranchia, the heterobranchs (meaning "different gill"), is a taxonomic clade of snails and slugs, which includes marine, aquatic, and terrestrial gastropod molluscs. Heterobranchia is one of the main clades of gastropods. Currently Het ...

.WoRMS (2020). "Lower Heterobranchia". Accessed at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1054700 on 2020-05-16 Although the great majority of Lower Heterobranchs are indeed marine, a few have succeeded in making the transition to

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

Description

The

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

shapes in this group are typically those that are seen in the sundial, pyramid, rissoella and orbitestellid families of snails. Bactroptyxis trachaea 041811

Taxonomy

2005 taxonomy

In the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, the Lower Heterobranchia is an Informal Group. Superfamilies within the Lower Heterobranchia include: *Unassigned to a superfamily (orbitestellid-shells) ** Family Cimidae ** † Family Dolomitellidae ** † Family Heterosubulitidae ** † Family Kuskokwimiidae ** † Family Misurinellidae **Family Orbitestellidae **Family Tjaernoeiidae **Family Xylodisculidae * superfamily Acteonoidea * superfamily Architectonicoidea * superfamily

Glacidorboidea The Glacidorbidae is a Taxonomy (biology), taxonomic family (biology), family of freshwater snails. Taxonomy 2005 taxonomy Glacidorbidae is the only family in the superfamily Glacidorboidea. Glacidorboidea has been classified within the info ...

* superfamily Mathildoidea * † superfamily Nerineoidea * superfamily Omalogyroidea * superfamily Pyramidelloidea * superfamily Ringiculoidea * superfamily Rissoelloidea * † superfamily Streptacidoidea * superfamily

Valvatoidea Valvatoidea is a superfamily of minute freshwater and marine snails, aquatic gastropod mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant ...

(Taxa that are exclusively fossil are indicated with a dagger †) For a more detailed taxonomy see: Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)#Informal group "Lower Heterobranchia" (= Allogastropoda)

2010 taxonomy

Jörger et al. (2010) have redefined major groups within the Heterobranchia: they moved

and Pyramidelloidea to

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 ...

.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. .

2014 taxonomy

Wägele et al. (2014):Wägele H., Klussmann-Kolb A., Verbeek E. & Schrödl M. (2014). "Flashback and foreshadowing—a review of the taxon Opisthobranchia". '' Organisms Diversity & Evolution'' 14(1): 133–149. moved Rissoelloidea and Acteonoidea from Lower Heterobranchia to

Euthyneura Euthyneura is a taxonomic infraclass of snails and slugs, which includes species exclusively from marine, aquatic and terrestrial gastropod mollusks in the clade Heterobranchia. Euthyneura are characterised by several autapomorphies, bu ...

2016 taxonomy

Kano et al. (2016): moved Ringiculoidea from Lower Heterobranchia to

. So the following taxa remain within the Lower Heterobranchia: *Unassigned to a superfamily (orbitestellid-shells) ** Family Cimidae ** † Family Dolomitellidae ** † Family Heterosubulitidae ** † Family Kuskokwimiidae ** † Family Misurinellidae **Family Orbitestellidae **Family Tjaernoeiidae **Family Xylodisculidae * superfamily Architectonicoidea * superfamily Mathildoidea * † superfamily Nerineoidea * superfamily Omalogyroidea * † superfamily Streptacidoidea * superfamily

References

{{Taxonbar, from=Q6430801