Helicidae
| Helicidae | |
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| Helix pomatia | |
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| Family: | Helicidae Rafinesque, 1815
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The Helicidae, sometimes known as the typical snails, are a taxonomic family of small to large, air-breathing, land snails. In other words, they are terrestrial pulmonate gastropod mollusks.
Several species in this family are edible, including Helix aspersa the garden snail, and Helix pomatia the "escargot".[1] The biology of these two species in particular has been much studied.
Shell description
The shells of these snails are mostly rather globular in shape. In some genera, such as Cepaea, the shells are brightly colored and patterned.
Anatomy
Animal is capable of complete retraction within the shell, the tail without mucous gland or projection.[2]
Mouth always provided with a jaw, which is striate, ribbed, sulcate or plicate, sometimes composed of several imbricating pieces; radula composed of many transverse horizontal series of teeth, the centrals tricuspidate, about the size of the laterals, laterals bicuspid, or tricuspid with the interior cusp obsolete, marginals usually wider than high, short with two or three small cusps.[2]
In the soft parts the most obvious distinction is the want of a caudal mucous pore in the Helices, and their possessing a sculptured jaw. Typically, there is a distinction in the dentition, although in some species the lateral teeth of Helices take on a pseudozonitoid appearance; even in such cases the extreme marginals in Helix remain short and very obtuse.[2]
This family of snails is defined by the anatomical presence of a diverticulum. Some genera within this family create and use love darts as part of their mating behavior. These snails have one dart apparatus. The dart sac has no accessory sac, and contains two tubular glands, inserted at the base of the dart sac.
In this family, the number of haploid chromosomes varies from 21 to 30 (according to the values in this table).[3]
Distribution
The family is native to Eurasia and belongs the Western Palearctic group..
However some of the species, such as for example Helix aspersa, have been introduced and become established in numerous different places worldwide.
Many accidental introductions happen because the eggs of most Helicidae are laid in the soil, and they may thus easily travel unnoticed along with landscaping plants.
Genera
Subfamilies and genera within the family Helicidae include:
After Fauna Europaea[4] and Taxonomy Browser[5] the family Helicidae includes the following subfamilies, tribus and genera:
Subfamily Ariantinae Mörch, 1864 - in this subfamily the glands are divided or undivided. The love darts contain tow to four blades. There is only one penial papilla.
- Arianta Turton, 1831
- Causa
- Chilostoma Fitzinger, 1833
- Cylindrus Fitzinger, 1833
- Drobacia
- Faustina
- Helicigona A. Férussac, 1821
- Isognomostoma Fitzinger, 1833
- Vidovicia
Subfamily Helicinae Rafinesque, 1815 - In this subfamily the glands are divided. The love dart has four blades or vanes.There are two penial papillae.
- Tribe Thebini Wenz, 1923 (the synonym Euparyphinae Perrot, 1939 has been declared an invalid name)
- Theba Risso, 1826 - Theba pisana (O. F. Müller, 1774)
- Tribe Helicini Rafinesque, 1815
- Allognathus
- Assyriella
- Cantareus Risso, 1826
- Cepaea Held, 1838
- Codringtonia
- Cornu Born, 1778
- Eobania P. Hesse, 1913
- Helix Linnaeus, 1758
- Hemicycla
- Iberus
- Idiomela T. Cockerell, 1921
- Lampadia
- Leptaxis
- Levantina
- Otala Schumacher, 1817
- Pseudotachea
- Tyrrhenaria
- Tribe Murellini Hesse, 1918
- Macularia
- Marmorana W. Hartmann, 1844 This genus might actually belong to the subfamily Ariantinae and not to the subfamily Helicinae, as has been assumed until now [6]
- Tacheocampylaea
- Tyrrheniberus
References
- ^ M.P. Kerney & R.A.D. Cameron. 1979. A field guide to the land snails of Britain and northwestern Europe. Collins, London.
- ^ a b c Tryon G. W. 1887 Manual of conchology; structural and systematic. With illustrations of the species. Second series: Pulmonata. Volume 3. Helicidae - Volume I. page 3-4.
- ^ Barker G. M.: Gastropods on Land: Phylogeny, Diversity and Adaptive Morphology. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, ISBN 0-85199-318-4. 1-146, cited pages: 139 and 142.
- ^ Fauna Europaea
- ^ Taxonomy Browser
- ^ Hartmut Nordsieck. April 2006. Higher classification of Helicoidea and the molecular analyses of their phylogeny.
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