Pristilomatidae

Vitrea subrimata, copyright O. Gargominy.

Belongs within: Limacoidei.

Snails of crystal
Published 5 July 2021

In many parts of the world, searching under pots or among other garden rubbish may turn up minute snails with translucent shells. Among the various families which might be found in this way are representatives of the family Pristilomatidae, commonly known as crystal snails.

Common crystal snail Vitrea crystallina, copyright O. Gargominy.

All members of the Pristilomatidae* are tiny: the minute gem snail Hawaiia minuscula, one species which has become widespread, is a giant within the family at close to three millimetres in diameter. The shells have a low spire, growing in more or less a disc shape, and are generally smooth or ornamented with very fine radial lines. In life, they are transparent or a cloudy white, explaining their vernacular name. Internal organs are often visible through the shell. The Pristilomatidae are part of the broader group of mostly tiny snails known as the Gastrodontoidea (which I’ve covered on this site earlier, albeit in a rather inept fashion). Even among this array, however, they are notably small. Within the gastrodontoids, the pristilomatids are primarily distinguished by the structure of the male genitalia, in which the vas deferens in attached to the proximal end of the penial tunica (a sheath of muscle tissue around the penis; Hausdorf 1998). However, there is a bit of an open question about how well supported they are as a group. Their distinguishing features could all be side effects of their reduced size.

*In older texts, you may find this family referred to as the Vitreidae, after one of the larger genera included. However, the name Pristilomatidae has priority.

Minute gem snail Hawaiia minuscula, copyright Chris Mallory.

Within their native range, crystal snails may mostly be found in western North America and the western Palaearctic. Several species, however, have become further distributed in association with humans. As such, they are mostly found in damp, disturbed habitats, such as gardens, nurseries and parks. They will be found in secluded locations such as under flower pots or buried among moss or leaf litter. Some species prefer to fully bury themselves within the soil. Some other members of the gastrodontoids are known to be predatory, feeding on small arthropods or other snails and their eggs, but I haven’t been able to find any direct reference to such habits among pristilomatids. It seems more likely that they prefer to feed on decaying fragments of vegetation. They do not seem to be regarded as presenting a challenge to the gardener; rather, they may provide their own small amount of assistance in keeping things tidy.

Systematics of Pristilomatidae
<==PristilomatidaeBR17
|--Pristiloma Ancey 1887 [Pristilomatinae, Pristilomatini, Pristilominae]BR05
| |--*P. stearnsi (Bland 1875) [=Zonites stearnsi]BR17
| `--P. lansingiBP90
|--Vitrea Fitzinger 1833BR17, SS10 [Vitreidae, Vitreinae, Vitreini]
| |--*V. diaphana (Studer 1820)BR17 [=Glischrus (Helix) diaphanaBR17, SS10, Vitrina diaphanaG40]
| |--V. botterii (Pfeiffer 1853)NB19
| |--V. cavannae (Paulucci 1881)NB19
| |--V. contracta (Westerlund 1871)NB19
| |--V. etrusca (Paulucci 1878)NB19
| |--V. garganoensis (Gittenberger & Eikenboom 2006) [=Lindbergia garganoensis]NB19
| |--V. gostelii Gümüş & Neubert 2012GN12
| |--V. indentataP15
| | |--V. i. indentataP15
| | `--V. i. umbilicataP15
| |--V. obliqua Meek & Hayden 1857TTE93
| |--V. pygmaea (Böttger 1880)SS10 [incl. Zonites crystallina contracta Westerlund 1873SS10, V. contractaBP90]
| |--V. riedelianaGN12
| |--V. subrimata (Reinhardt 1871)NB19
| `--V. trolli (Wagner 1922)NB19
|--Lindbergia Riedel 1959NB19
| |--L. beroni Riedel 1984NB19
| |--L. orbicularis (Riedel 1962)NB19
| |--L. pageti Riedel 1968G08
| |--L. parnonensis Gittenberger 2008G08
| |--L. pinteri Riedel 1981NB19
| |--L. pseudoillyrica Riedel 1960NB19
| |--L. spiliaenymphus Riedel 1959NB19
| `--L. stylokamarae Riedel 1981NB19
|--Gollumia Riedel 1988NB19
|--Hawaiia Gude 1911NB19 [incl. Johannesoconcha Preston 1913SS10, Magillivrayella Preston 1913SS10]
| `--H. minuscula (Binney 1840) (see below for synonymy)SS10
|--Spinophallus Riedel 1962NB19
|--Gyralina Andreae 1902NB19
|--Troglovitrea Negrea & Riedel 1968NB19
`--Taurinellushka Balashov 2014NB19

Hawaiia minuscula (Binney 1840) [=Helix minuscula; incl. Magillirayella crystallina Preston 1913, Helix kawaiensis Pfeiffer in Reeve 1854, *Hawaiia kawaiensis, Johannesoconcha multivolva Preston 1913, Helix (Patula) unwini Brzier 1889]SS10

*Type species of generic name indicated

References

[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.

[BR17] Bouchet, P., J.-P. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nützel, P. Parkhaev, M. Schrödl & E. E. Strong. 2017. Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia 61 (1–2): 1–526.

[BP90] Burch, J. B., & T. A. Pearce. 1990. Terrestrial Gastropoda. In: Dindal, D. L. (ed.) Soil Biology Guide pp. 201–309. John Wiley & Sones: New York.

[G08] Gittenberger, E. 2008. Two problematic, troglophilous gastropods from the Peloponnese, Greece (Gastropoda: Pulmonata: Zonitidae). Zoologische Mededelingen 82 (28): 275–280.

[G40] Gray, J. E. 1840. A Manual of the Land and Fresh-water Shells of the British Islands, with figures of each of the kinds. By William Turton, M.D. A new edition, thoroughly revised and much enlarged. Longman, Orme, Brown, Green, and Longmans: London.

[GN12] Gümüș, B. A., & E. Neubert. 2012. New taxa of terrestrial molluscs from Turkey (Gastropoda, Pristilomatidae, Enidae, Hygromiidae, Helicidae). ZooKeys 171: 17–37.

Hausdorf, B. 1998. Phylogeny of the Limacoidea sensu lato (Gastropoda: Stylommatophora). Journal of Molluscan Studies 64 (1): 35–66.

Hausdorf, B. 2000. Biogeography of the Limacoidea sensu lato (Gastropoda: Stylommatophora): vicariance events and long-distance dispersal. Journal of Biogeography 27: 379–390.

[NB19] Nardi, G., A. Braccia, S. Cianfanelli & M. Bodon. 2019. Revision of the systematic position of Lindbergia garganoensis Gittenberger & Eikenboom, 2006, with reassignment to Vitrea Fitzinger, 1833 (Gastropoda, Eupulmonata, Pristilomatidae). Basteria 83 (1–3): 19–28.

[P15] Pilsbry, H. A. 1915. Mollusca of the southwestern states, VI: the Hacheta Grande, Florida, and Peloncillo Mountains, New Mexico. Proceedings of the Academy of Natural Sciences of Philadelphia 67 (2): 323–350, pls 5–7.

[SS10] Stanisic, J., M. Shea, D. Potter & O. Griffiths. 2010. Australian Land Snails vol. 1. A. field guide to eastern Australian species. Bioculture Press: Mauritius.

[TTE93] Tracey, S., J. A. Todd & D. H. Erwin. 1993. Mollusca: Gastropoda. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 131–167. Chapman & Hall: London.

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