Trochulus

Trochulus
	An older adult individual of Trochulus hispidus with most of the hairs worn off of the shell
	Five views of a shell of Trochulus hispidus
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Heterobranchia; clade Euthyneura; clade Panpulmonata; clade Eupulmonata; clade Stylommatophora; informal group Sigmurethra
Superfamily:	Helicoidea
Family:	Hygromiidae
Subfamily:	Hygromiinae
Tribe:	Trochulini
Genus:	Trochulus; Chemnitz, 1786[1]
Synonyms
	Trichia Hartmann, 1840[2]

Trochulus is a genus of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the subfamily subfamily Trochulininae of the family Hygromiidae, the hairy snails and their allies.

Taxonomy

Trichia Hartmann, 1840[2] is a junior synonym of Trochulus Chemnitz, 1786.[3]

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).[4] Based on molecular analyses, Trochulus lubomirski does not belong to the genus Trochulus.[5] Trochulus lubomirski (Ślósarski, 1881) is now recognized as Plicuteria lubomirski (Ślósarski, 1881).

Species

A younger individual of Trochulus villosus on a leaf

The speciation centre for the genus Trochulus is in the Alps.[6]

The type species of this genus is Trochulus hispidus.

Species within the genus Trochulus include:[7][8]

Trochulus alpicola (Eder, 1921)
Trochulus ataxiacus (Fagot, 1884)
Trochulus biconicus (Eder, 1917) - synonym: Trichia biconica
Trochulus glyptus (Locard, 1880) - synonym: Trochulus caelatus (Studer, 1820) - synonym: Trichia caelata[9]
Trochulus clandestinus (Hartmann, 1821)
Trochulus coelomphala (Locard, 1888)
Trochulus graminicola (Falkner, 1973) - synonym: Trichia gramnicola
Trochulus hispidus (Linnaeus, 1758) - synonyms: Trichia hispida (Linnaeus, 1758), Trochulus sericeus (Draparnaud, 1801)[10]
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 (Ślósarski, 1881)
Trochulus oreinos (Wagner, 1915): synonym of Noricella oreinos (Wagner, 1915)
Trochulus waldemari (Wagner, 1912): synonym of Xerocampylaea waldemari (Wagner, 1912)

Hair on shells

The periostracum 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)[5] 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.[5]

Feeding habits

Trochulus species in moist habitats prefer to forage on large-leaved herbaceous plants like Adenostyles, Urtica (nettles), Homogyne or Tussilago (coltsfoot etc).[5]

References

This article incorporates CC-BY-2.0 text from reference.[5]

(in German) Chemnitz J. H. (1786) Neues systematisches Conchylien-Cabinet. Neunten Bandes zwote Abtheilung, enthaltend die ausführliche Beschreibung von den Land- und Flußschnecken, oder von solchen Conchylien, welche nicht im Meere, sondern auf der Erde und in süssen Wassern zu leben pflegen. Mit zwanzig nach der Natur gemalten und durch lebendige Farben erleuchteten Kupfertafeln. pp. I-XXVI [= 1-26], 1-194, Tab. 117-136. Nürnberg. (Raspe).
(in German) Hartmann J. D. W. (1844) Erd- und Süsswasser-Gasteropoden der Schweiz. Mit Zugabe einiger merkwürdigen exotischen Arten. I. Band. pp. i-xx [= 1-20], 1-227, Tab. I-XII [= 1-12], I-XII [sic, = 13-24], 25-84. St. Gallen. (Scheitlin & Zollikofer).
(30 September 2004) ICZN Opinion 2079 Archived 2008-05-17 at the Wayback Machine. Bulletin of Zoological Nomenclature 61(3).
Schileyko A. A. (February 1978) "On the systematics of Trichia s. lat. (Pulmonata: Helicoidea: Hygromiidae)". Malacologia 17(1): 1-56.
Pfenninger, Markus; Hrabáková, Magda; Steinke, Dirk; Dèpraz, Aline (2005). "Why do snails have hairs? A Bayesian inference of character evolution". BMC Evolutionary Biology. 5: 59. doi:10.1186/1471-2148-5-59. PMC 1310604. PMID 16271138.
(in Czech) Hrabáková M., Juřičková L. & Petrusek A. (2006) "Problematika rodu Trochulus (Mollusca, Gastropoda) v České republice". In: Bryja J. & Zukal J. (eds.) 2006. Zoologické dny Brno 2006. Sborník abstraktů z konference 9.-10. února. ISBN 80-903329-4-3, 268 pp., pages 42-43.
Species in genus Trochulus. AnimalBase. Accessed 29 December 2008.
Trichia. Fauna Europaea, accessed 2 December 2009.
Trichia (Trichia) glypta. Molluscs of central Europe, accessed 2 December 2009.
Proćków, Małgorzata; Kuźnik-Kowalska, Elżbieta; Mackiewicz, Paweł (2017-08-01). "Phenotypic plasticity can explain evolution of sympatric polymorphism in the hairy snail Trochulus hispidus (Linnaeus, 1758)". Current Zoology. 63 (4): 389–402. doi:10.1093/cz/zow082. ISSN 1674-5507. PMC 5804198. PMID 29491999.