Zonitidae, common name the true glass snails, are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of mostly rather small, air-breathing land snails,

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

pulmonate gastropod

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s in the superfamily Zonitoidea. Zonitidae is the only family in the superfamily Zonitoidea. The family's

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...

is '' Zonites'', established by Pierre Denys de Montfort in 1810. This family has no subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).

Distribution

The distribution of the Zonitidae encompasses the western Palearctic.

Shell description

The spiral, heliciform shells of these snails are flattened in shape with a very low

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires a ...

. The shell is perforate or umbilicate. The lip of the

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

is simple, lacking thickened margin. These shells are more or less transparent as if made of glass, hence the popular name "glass snails". The shells are colorless or of an amber to brownish color.

Biology

Some snails in genera within this family create and use

love dart A love dart (also known as a gypsobelum, shooting darts, or just as darts) is a sharp, calcareous or chitinous dart which some hermaphroditic land snails and slugs create. Love darts are both formed and stored internally in a dart sac. These ...

s as part of their mating behavior. In this family, the number of haploid

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

s lies between 21 and 25 and also lies between 31 and 35, but other values are also possible (according to the values in this table).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, . 1–146, cited pages: 139 and 142.

Ecology

These snails live in damp places under stones and similar objects. The true glass snails are usually nocturnal.

Genera

Genera within the family Zonitidae include: * '' Aegopis'' Fitzinger, 1833 * '' Aegopinella'' Lindholm, 1927 * '' Allaegopis'' Riedel, 1979 * '' Balcanodiscus'' Riedel & Urbanski, 1964 * '' Brazieria'' Ancey, 1887 * '' Doraegopis'' Riedel, 1982 * '' Eopolita'' Pollonera, 1916 *'' Glyphyalinia'' Martens, 1892 * '' Gollumia'' Riedel, 1988 * '' Meledella'' Sturany, 1908 * '' Mesomphix'' Rafinesque, 1819 * '' Ogaridiscus'' Dall, 1877Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. ''Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks''. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp. * '' Paraegopis'' Hesse, 1910 * '' Paravitrea'' Pilsbry, 1898 * '' Retinella'' Fischer, 1877 * '' Thasiogenes'' Riedel, 1998 * '' Troglaegopis'' Riedel & Radja, 1983 * '' Turcozonites'' Riedel, 1987 *'' Ventridens'' Binney & Bland, 1869 * '' Zonites'' Montfort, 1810 – type genus

Cladogram

The following

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

shows the phylogenic relationships of this family to other families in the limacoid clade:Hausdorf B. (2000). "Biogeography of the Limacoidea sensu lato (Gastropoda: Stylommatophora): Vicariance Events and Long-Distance Dispersal". '' Journal of Biogeography'' 27(2): 379–390.
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