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.
Shell description
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.
Anatomy
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.
Genetics
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 ().
Distribution
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.
Taxonomy
The family Helicidae contains 3 subfamilies (according to molecular phylogenetic analyses):
Subfamily Helicinae Rafinesque, 1815
Genital system anatomy (does not apply on all species, as derived states are found in some of them): mucous glands divided into 2 or more branches, love dart with four blades (vanes) along its length, two penial papillae/verges.
Tribe Allognathini Westerlund, 1903
Allognathus
Cepaea Held, 1838
Hemicycla
Iberus
Idiomela T. Cockerell, 1921
Lampadia
Tribe Helicini Rafinesque, 1815
Aristena Psonis, Vardinoyannis & Poulakakis, 2022
Amanica Nordsieck, 2017
Caucasotachea Boettger, 1909
Codringtonia Kobelt, 1898
Helix Linnaeus, 1758 - type genus
Isaurica Kobelt, 1901
Levantina Kobelt, 1871
Lindholmia Hesse, 1918
Maltzanella Hesse, 1917
Neocrassa Subai, 2005
Tribe Thebini Wenz, 1923
A 2022 phylogenetic analysis proposed that all groups of the Maghreb radiation belonged to a single tribe, Thebini, without support for a separate Otalini tribe. The same study proposed a new tribe, Maculariini trib. nov. containing the genus Macularia due to the wide geographic disjunction between the western Alpine Macularia and the primarily Maghrebian Thebini tribe. Cantareus Risso, 1826 Cornu Born, 1778 Eobania P. Hesse, 1913 Eremina Pfeiffer, 1855 Gyrostomella P. Hesse, 1911 Loxana Pallary, 1899 Massylaea Möllendorff, 1898 Otala Schumacher, 1817 Rossmaessleria P. Hesse, 1907 Theba Risso, 1826
Tribe Maculariini Neiber, Korábek, Glaubrecht & Hausdorf, 2021
Macularia Albers, 1850
Subfamily Murellinae Hesse, 1918
Genital system anatomy (does not apply on all species, as derived states are found in some of them): mucous glands weakly branched or undivided, love dart with four blades along its length, one penial papilla.
Distributed in Sardinia, Corsica, the Apennine Peninsula and Sicily. Marmorana W. Hartmann, 1844 Tacheocampylaea Tyrrheniberus