The Limacoidei is a

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

of air-breathing

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known as ...

semislug Semi-slugs, also spelled semislugs, are land gastropods whose shells are too small for them to retract into, but not quite vestigial. The shell of some semi-slugs may not be easily visible on casual inspection, because the shell may be covered ...

s and

slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

pulmonate Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...

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. T ...

molluscs 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 taxon, extant species of molluscs are recognized. The number of fossil sp ...

in the suborder

Helicina ''Helicina'' is a genus of tropical and subtropical land snails with an operculum, terrestrial gastropod mollusks. This is the type genus of its family (Helicinidae) and subfamily ( Helicinae), as well as the superfamily Helicinoidea. This ...

Distribution

The original ancestral area of limacoid families is thought to be the

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

region and south-eastern Asia.

Etymology

The word "limacoid" means "resembling a slug".

Typography of the name

In 1998, for the same taxon, Hausdorf used the name Limacoidea

sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...

. The name of this

taxon In biology, a taxon (back-formation from ''taxonomy''; plural 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 nam ...

, the limacoid clade, was written by Bouchet & Rocroi (2005) with

quotation mark Quotation marks (also known as quotes, quote marks, speech marks, inverted commas, or talking marks) are punctuation marks used in pairs in various writing systems to set off direct speech, a quotation, or a phrase. The pair consists of an ...

s like this: "limacoid clade". Other typographical variants are used by various other authors, for example capitalizing and restricting the use of the quote marks thus: "Limacoid" clade and "Limacoid clade".

2003 taxonomy by Schileyko

The study of A. Schileyko in this group, published in parts 8–11 of his monograph between 2002 and 2003, did not discuss the system that Hausdorf had proposed. However, Schileyko refers to the work of Hausdorf, where this system was proposed, in part 10 (2003) on p. 1390. So he was acquainted with this system before 2003. Alternative taxonomy is as follows (subfamilies listed only for Helicarionidae and Zonitidae): *Superfamily Helicarionoidea **Family Euconulidae **Family Trochomorphidae **Family Helicarionidae ***Subfamily Geotrochinae ***Subfamily Helicarioninae ***Subfamily Papuarioninae ***Subfamily Urocyclinae **Family Gymnarionidae **Family Rhysotinidae **Family Ariophantidae **Family Ostracolethidae **Family Ryssotidae **Family Milacidae *Superfamily Dyakioidea **Family Dyakiidae **Family Staffordiidae *Superfamily Gastrodontoidea **Family Gastrodontidae *Superfamily Zonitoidea **Family Zonitidae ***Subfamily Pristilomatinae ***Subfamily Godwiniinae ***Subfamily Zonitinae ***Subfamily Oxychilinae **Family Daudebardiidae **Family Parmacellidae *Superfamily Trigonochlamydoidea **Family Trigonochlamydidae *Superfamily Vitrinoidea **Family Vitrinidae *Superfamily Limacoidea **Family Limacidae **Family Agriolimacidae **Family Boettgerillidae Moreover, after these groups, in the same infraorder Limacoinei, Schileyko listed six more superfamilies: Camaenoidea, Xanthonychoidea, Helicoidea, Polygyroidea, Hygromioidea and Arionoidea.

2005 taxonomy by Bouchet & Rocroi

Explanatory note

For this particular group of families, Bouchet & Rocroi adapted the taxonomic approach which was originally published by German malacologist Bernhard Hausdorf in 1998 in the ''Journal of Molluscan Studies''. http://mollus.oxfordjournals.org/cgi/content/abstract/64/1/35 Bouchet & Rocroi clearly state, on p. 283: However, in their paper, Bouchet & Rocroi (apparently accidentally) failed to show, graphically or typographically, ''any'' coverage of the limacoid clade in the taxonomic section of their paper, on pp. 268–269. Because of this omission, some authors have subsequently (mistakenly) included in the "limacoid clade" the two following superfamilies:

Arionoidea Arionoidea is a taxonomic group, superfamily of air-breathing land slugs, shell-less terrestrial pulmonate gastropod mollusks. Families Families within the superfamily Arionoidea include: * Arionidae * Anadenidae * Ariolimacidae * Bin ...

and

Helicoidea Helicoidea is a taxonomic superfamily of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Stylommatophora. Taxonomy 2005 taxonomy There are 19 families within the superfamily Helicoidea according to the ta ...

. This misunderstanding was copied by Poppe & Tagaro (2006)Poppe G. T. & Tagaro S. (23 February 2006)
''The New Classification of Gastropods According to Bouchet & Rocroi, 2005''
Visaya Net. who attempted to explain the changes within this taxonomy to the public. This same error is reproduced in various other internet sources.

Taxonomic list

The taxonomy of Bouchet and Rocroi shows the "limacoid clade" as follows: (Families that are exclusively fossil are indicated with a dagger †) *Superfamily Staffordioidea **Family

Staffordiidae Staffordiidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Trochomorphoidea. MolluscaBase eds. (2021). MolluscaBase. Staffordiidae Thiele, 1931. Accessed through: World Register of Mar ...

*Superfamily Dyakioidea **Family

Dyakiidae Dyakiidae is a family of air-breathing land snails terrestrial pulmonate gastropod mollusks in the superfamily Trochomorphoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Some of the species in this family are sin ...

*Superfamily

Gastrodontoidea Gastrodontoidea is a taxonomic superfamily of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the limacoid clade. Taxonomy According to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), families in this superfamily ...

**Family

Gastrodontidae Gastrodontidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Gastrodontoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). MolluscaBase eds. (2020). MolluscaBase ...

**Family

Chronidae Chronidae is a family of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the superfamily Trochomorphoidea within the superorder Eupulmonata. MolluscaBase eds. (2021). MolluscaBase. Chronidae Thiele, 1931. Accessed through: ...

**Family

Euconulidae Euconulidae is a taxonomic family of minute, air-breathing land snails, terrestrial pulmonate gastropod mollusks or micromollusks in the superfamily Trochomorphoidea. This land snail family is closely allied to the Zonitidae, the glass snails. ...

**Family

Oxychilidae Oxychilidae is a taxonomic family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Gastrodontoidea. Distribution The distribution of Oxychilidae includes the Nearctic, western-Palearctic, eastern-Palear ...

**Family

Pristilomatidae Pristilomatidae is a taxonomic family of air-breathing land snails, terrestrial gastropod mollusks in the superfamily Gastrodontoidea. According to the 2005 taxonomy of the Gastropoda by Bouchet & Rocroi these snails belong to the "limacoid ...

**Family

Trochomorphidae Trochomorphidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Gastrodontoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Since 2017, its classification has bee ...

**Fossil taxa probably belonging to the Gastrodontoidea ***Subfamily † Archaeozonitinae ***Subfamily † Grandipatulinae ***Subfamily † Palaeoxestininae *Superfamily

Parmacelloidea Parmacelloidea is a superfamily of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the clade Stylommatophora and the informal group Pulmonata. These are limacoid or keelback slugs. Families Families within the superfamily ...

**Family

Parmacellidae Parmacellidae is a family of air-breathing land slugs, terrestrial pulmonate gastropod mollusks within the superfamily Parmacelloidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). This family has no subfamilies (ac ...

**Family

Milacidae Milacidae is a family of air-breathing, keeled, land slugs. These are shell-less terrestrial gastropod mollusks in the superfamily Parmacelloidea. This family has no subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, ...

**Family

Trigonochlamydidae Trigonochlamydidae is a family of air-breathing land slugs, terrestrial gastropod molluscs in the clade Eupulmonata (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Distribution The native distribution of Trigonochla ...

*Superfamily Zonitoidea **Family

Zonitidae Zonitidae, common name the true glass snails, are a family of mostly rather small, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Zonitoidea. Zonitidae is the only family in the superfamily Zonitoidea. Th ...

*Superfamily

Helicarionoidea Helicarionoidea is a superfamily of air-breathing land snails and semi-slugs, terrestrial pulmonate gastropod mollusks in the infraorder Limacoidei. Families There are three families within the superfamily Helicarionoidea: * Helicarionidae ...

**Family

Helicarionidae Helicarionidae is a family of air-breathing land snails or semi-slugs, terrestrial pulmonate gastropod mollusks in the superfamily Helicarionoidea. Distribution The distribution of Helicarionidae includes the eastern Palearctic, Malagasy, Ind ...

**Family

Ariophantidae Ariophantidae is a taxonomic family of air-breathing land snails and semi-slugs, terrestrial pulmonate gastropod mollusks in the superfamily Helicarionoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Distribution ...

**Family

Urocyclidae Urocyclidae is a family of air-breathing land snails, semi-slugs and land slugs, terrestrial pulmonate gastropod mollusks in the superfamily Helicarionoidea, (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Some spec ...

*Superfamily

Limacoidea Limacoidea is a taxonomic superfamily of medium-sized to large, air-breathing land slugs and snails. They are terrestrial pulmonate gastropod mollusks in the infraorder Stylommatophora (according to the taxonomy of the Gastropoda by Bouchet ...

**Family

Limacidae Limacidae, also known by their common name the keelback slugs, are a taxonomic family of medium-sized to very large, air-breathing land slugs, terrestrial pulmonate gastropod molluscs in the superfamily Limacoidea. Distribution The distr ...

**Family

Agriolimacidae ''Agriolimacidae'' is a family of small and medium-sized land slugs, or shell-less snails, terrestrial molluscs, terrestrial pulmonate gastropod mollusc, mollusks. Distribution Distribution of Limacidae is Holarctic, this include: Nearctic, wes ...

**Family

Boettgerillidae ''Boettgerilla'' is a genus of air-breathing land slugs, terrestrial pulmonate gastropod molluscs in the family Boettgerillidae. The generic name ''Boettgerilla'' is named after the German malacologist Oskar Boettger. Taxonomy ''Boettger ...

**Family

Vitrinidae Vitrinidae is a family of small, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Limacoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). MolluscaBase eds. (2021). MolluscaBa ...

Cladogram

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

showing phylogenic relations of families in the limacoid clade:Hausdorf B. (2000). "Biogeography of the Limacoidea sensu lato (Gastropoda: Stylommatophora): Vicariance Events and Long-Distance Dispersal". ''

Journal of Biogeography The ''Journal of Biogeography'' is a peer-reviewed scientific journal in biogeography that was established in 1974. It covers aspects of spatial, ecological, and historical biogeography. The founding editor-in-chief was David Watts, followed by J ...

'' 27(2): 379–390.
JSTOR
As explained in the previous section, the superfamilies

and

do not belong to the limacoid clade. However, they are sometimes mistakenly included in this taxon.

References

* Bouchet P., Rocroi J.P., Hausdorf B., Kaim A., Kano Y., Nützel A., Parkhaev P., Schrödl M. & Strong E.E. (2017). Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia. 61(1-2): 1-526 {{Taxonbar, from1=Q57262978, from2=Q11247992 Stylommatophora