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 invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary t ...
s and
sea snail
Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the abse ...
s, (
marine gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. The ...
mollusks
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estim ...
) within the
subclass Heterobranchia
Heterobranchia, the ''heterobranchs'' (meaning "different-gilled snails"), is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.
Heterobranchia is one of the main clades of gastropods. Cur ...
.
[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. Although the term specifically excludes seawater and brackish water, it does inclu ...
.
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
** Thin-shell structure
Science Biology
* Seashell, a hard o ...
shapes in this group are typically those that are seen in the sundial, pyramid, rissoella and orbitestellid families of snails.
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 taxonomic family of freshwater snails.
Taxonomy 2005 taxonomy
Glacidorbidae is the only family in the superfamily Glacidorboidea. Glacidorboidea has been classified within the informal group Lower Heterobranchia in th ...
* 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 mollusks in the informal group Lower Heterobranchia.MolluscaBase eds. (2020). MolluscaBase. Valvatoidea Gray, 1840. Accessed through: World Register of Mari ...
(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
Glacidorboidea
The Glacidorbidae is a taxonomic family of freshwater snails.
Taxonomy 2005 taxonomy
Glacidorbidae is the only family in the superfamily Glacidorboidea. Glacidorboidea has been classified within the informal group Lower Heterobranchia in th ...
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 gast ...
.
[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. It ...
'' 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, but are n ...
.
2016 taxonomy
Kano et al. (2016):
moved
Ringiculoidea 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, but are n ...
.
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
Valvatoidea
Valvatoidea is a superfamily of minute freshwater and marine snails, aquatic gastropod mollusks in the informal group Lower Heterobranchia.MolluscaBase eds. (2020). MolluscaBase. Valvatoidea Gray, 1840. Accessed through: World Register of Mari ...
References
{{Taxonbar, from=Q6430801