Trichia Hartmann, 1840 is a junior synonym of Trochulus Chemnitz, 1786, meaning the name was published after Trochulus to describe the same group of organisms. As such, Trochulus is considered the valid name, but nearly every malacological work prior to 2006 referred to the genus as Trichia.
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 lubomirskii (Ślósarski, 1881).
Most Trochulus species have hair-like features on their periostracum (the outermost layer of the shell). Some of the hair-less species still have hairs as juveniles. Hairy shells seemed to be the ancestral character shared by all members within the genus, and the feature was probably lost three times independently later.
These losses were correlated with a shift from humid to dry habitats, hinting at an adaptive function: the hypothesis was that these hair-like protein structures improve movement in moist habitats. In 2005, experiments by Pfenninger and colleagues showed that haired shells attached more easily to wet surfaces. Snails could better cling to their herbaceous food plants during foraging under high humidity levels. The absence of hairs in some Trochulus species, which consequently lose this potential adaptive function, could then be linked to habitat shifts toward drier environments.
Feeding habits
Trochulus species in moist habitats prefer to forage on large-leaved herbaceous plants like Adenostyles, Urtica (nettles), Homogyne or Tussilago (e.g., coltsfoot).
References
This article incorporates CC-BY-2.0 text from reference.
↑(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).
12(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).
↑(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. ISBN80-903329-4-3, 268 pp., pages 42-43.
Dépraz, A.; Rathey, E.; Hausser, J. (2008). "Characterization of 13 polymorphic microsatellite loci for two land snail species, Trochulus villosus and T. sericeus (Gastropoda: Pulmonata: Hygromiidae)". Molecular Ecology Resources. 8 (3): 704–706. doi:10.1111/j.1471-8286.2007.02055.x. PMID21585877. S2CID205626994.
