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Concept
Helicidae
Résumé
Helicidae is a large, diverse family of western Palaearctic, medium to large-sized, air-breathing land snails, sometimes called the "typical snails." It includes some of the largest European land snails, several species are common in anthropogenic habitats, and some became invasive on other continents. A number of species in this family are valued as food items, including Cornu aspersum (formerly Helix aspersa; "petit gris") the brown or garden snail, and Helix pomatia (the "escargot"). The biologies of these two species in particular have been thoroughly studied and documented.
The shells are usually flattened or depressed conical. Globular shells are found in the genera Helix, Maltzanella, Lindholmia, Cornu, Cantareus, Eremina, and Idiomella. One species, Cylindrus obtusus, has a cylindrical shell. In some genera, especially in Cepaea, the shells are brightly colored and patterned.
Helicidae typically have a ribbed jaw, bursa copulatrix with a diverticulum, and one dart sac accompanied by a pair of (usually) branched, tubular mucous glands inserting at the base of the dart sac.
In this family, the number of haploid chromosomes lies between 22 and 30.
In the " project, four species (Cepaea nemoralis, Cepaea hortensis, Cornu aspersum, and Arianta arbustorum) are scheduled for whole genome sequencing and assembly ().
The core of helicids is distributed in from the Caucasus through Turkey and Europe to North Africa. However, some genera or species live beyond these limits. Helicids occur on Cape Verde (Eremina), Canary Islands (Theba, Hemicycla) and the Madeira Archipelago (Lampadia, Idiomela). Levantina extends far south in western Arabia, and Eremina desertella is distributed as south as Sudan, Eritrea and Puntland in Somalia. Cepaea hortensis lives on Iceland and in a small area in eastern Canada. Some species, notably Cornu aspersum and Theba pisana have been introduced and become established in numerous different areas worldwide.
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