''Trochulus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of small 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 ...

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 ...

mollusk 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 e ...

s in the subfamily subfamily Trochulininae of the family

Hygromiidae Hygromiidae is a taxonomic family of small to medium-sized air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea. Helicellidae Ihering, 1909 Anatomy Some snails in genera within this family create ...

, the hairy snails and their allies.

Taxonomy

''Trichia'' Hartmann, 1840 is a

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

of ''Trochulus'' Chemnitz, 1786. Nearly every malacological work prior to 2006 used the name ''Trichia'' instead of the (now considered valid) name ''Trochulus''. The genus '' Plicuteria'' Schileyko, 1978 has been once recognized as a subgenus within ''Trochulus'' by Schileyko (1978). Based on molecular analyses, ''Trochulus lubomirski'' does not belong to the genus ''Trochulus''. ''Trochulus lubomirski'' (Ślósarski, 1881) is now recognized as '' Plicuteria lubomirski'' (Ślósarski, 1881).

Species

The

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

centre for the genus ''Trochulus'' is in the

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of this genus is ''

Trochulus hispidus ''Trochulus hispidus'', previously known as ''Trichia hispida'', common name, the "hairy snail", is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies. ...

''. Species within the genus ''Trochulus'' include: * '' Trochulus alpicola'' (Eder, 1921) * '' Trochulus ataxiacus'' (Fagot, 1884) * ''

Trochulus biconicus ''Trochulus biconicus'' is a species of air-breathing land snail, a pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies. This species is endemic Endemism is the state of a species being found in a s ...

'' (Eder, 1917) - synonym: ''Trichia biconica'' * '' Trochulus glyptus'' (Locard, 1880) - synonym: ''Trochulus caelatus'' (Studer, 1820) - synonym: '' Trichia caelata'' * '' Trochulus clandestinus'' (Hartmann, 1821) * '' Trochulus coelomphala'' (Locard, 1888) * '' Trochulus graminicola'' (Falkner, 1973) - synonym: ''Trichia gramnicola'' * ''

'' (

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of Systema Naturae, 10th edition of ''Systema Naturae'', the sta ...

) - synonyms: ''Trichia hispida'' (

), ''Trochulus sericeus'' (Draparnaud, 1801) * '' Trochulus montanus'' (Studer, 1820) * '' Trochulus phorochaetius'' (Bourguignat, 1864) * '' Trochulus plebeius'' (Draparnaud, 1805) - synonym: ''Trichia plebeia'' * '' Trochulus striolatus'' (C. Pfeiffer, 1828) - synonym: ''Trichia striolata'' * '' Trochulus suberectus'' (Clessin, 1878) * '' Trochulus villosus'' (Draparnaud, 1805) * '' Trochulus villosulus'' - (Rossmässler, 1838) - synonym: ''Trichia villosula'' (Rossmässler, 1838) ;Species brought into synonymy: * ''Trochulus erjaveci'' (Brusina, 1870): synonym of '' Xerocampylaea erjaveci'' (Brusina, 1870) * ''Trochulus lubomirskii'' (Ślósarski, 1881): synonym of ''

Plicuteria lubomirskii ''Plicuteria lubomirski'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies. Taxonomy The spelling of the name is currently disputed. In the ori ...

'' (Ślósarski, 1881) * ''Trochulus oreinos'' (Wagner, 1915): synonym of ''

Noricella oreinos ''Noricella oreinos'' is a species of small, air-breathing land snail, a terrestrial animal, terrestrial pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies.MolluscaBase (2018). Noricella oreinos (Wagner, 191 ...

'' (Wagner, 1915) * ''Trochulus waldemari'' (Wagner, 1912): synonym of '' Xerocampylaea waldemari'' (Wagner, 1912)

Hair on shells

The

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and ...

of the shells of most ''Trochulus'' species has hair-like features. Some of the hair-less species do possess hairs as juveniles. Hairy shells appeared to be the ancestral character state in the genus ''Trochulus'', a feature which has most probably been lost three times independently. These losses were correlated with a shift from humid to dry habitats, indicating an adaptive function of hairs in moist environments. It had been previously hypothesised that these costly protein structures of the outer shell layer facilitate locomotion in moist habitats. Experiments by Pfenninger et al. (2005) showed an increased adherence of haired shells to wet surfaces. The possession of hairs facilitates the adherence of the snails to their herbaceous food plants during foraging, when humidity levels are high. The absence of hairs in some ''Trochulus'' species could thus be explained as a loss of the potential adaptive function linked to habitat shifts.

Feeding habits

''Trochulus'' species in moist habitats prefer to forage on large-leaved herbaceous plants like ''

Adenostyles ''Adenostyles'' is a genus of flowering plants in the sunflower family Asteraceae, and of the tribe Senecioneae. It was described as a genus in 1816. ''Adenostyles'' occur in the temperate climates of the northern hemisphere, mainly in Europe and ...

'', ''

Urtica ''Urtica'' is a genus of flowering plants in the family Urticaceae. Many species have stinging hairs and may be called nettles or stinging nettles, although the latter name applies particularly to ''Urtica dioica''. ''Urtica'' species are food f ...

'' (nettles), '' Homogyne'' or ''

Tussilago ''Tussilago farfara'', commonly known as coltsfoot, is a plant in the tribe Senecioneae in the family Asteraceae, native to Europe and parts of western and central Asia. The name "tussilago" is derived from the Latin ''tussis'', meaning cough, an ...

'' (coltsfoot etc).

References

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Taxonomy

Species

Hair on shells

Feeding habits

References

Further reading