''Steromphala varia'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

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 ...

in the

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

Trochidae The Trochidae, common name top-snails or top-shells, are a family of various sized sea snails, marine gastropod molluscs in the subclass Vetigastropoda. This family is commonly known as the top-snails because in many species the shell resembles ...

, the top snails.MolluscaBase eds. (2020). MolluscaBase. Steromphala varia (Linnaeus, 1758). Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=1039845 on 2020-12-30

Description

The size of the shell varies between 8 mm and 15 mm. The solid, umbilicate shell has a conical shape. Its color is a dull, lusterless yellowish white or pinkish, with flexuous radiating cinereous or violaceous stripes below the suture. tTe entire surface is finely mottled and dotted with yellowish or violaceous and white. The short

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 are ...

is conical, not acuminate as in ''

Gibbula ardens ''Gibbula ardens'' is a species of small sea snail, known as top snails or top shells, marine gastropod molluscs in the family Trochidae, the top snails.Gofas, S. (2013). Gibbula ardens (Salis Marschlins, 1793). Accessed through: World Register o ...

'' and ''

Gibbula umbilicaris ''Steromphala umbilicaris'' is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.MolluscaBase eds. (2020). MolluscaBase. Steromphala umbilicaris (Linnaeus, 1758). Accessed through: World Register of Mar ...

''. The about six

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

s are flattened and separated by slightly impressed sutures. They are encircled by numerous fine striae. The

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

is obtusely angular at the periphery. The large

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 opt ...

is very oblique and is smooth within. The oblique columella is straightened. The umbilicus is funnel-shaped and whitish within.Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
/ref> This species is host to the

ectoparasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s '' Trochicola entericus'' Dollfus, 1914 and '' Lichomolgus trochi'' Canu, 1899

Distribution

This species occurs in the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

and in the Atlantic Ocean off

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

References

* Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification''. Collection Patrimoines Naturels, 50: pp. 180–213

External links

* Samadi L. & Steiner G. (2010). "Conservation of ParaHox genes' function in patterning of the digestive tract of the marine gastropod ''Gibbula varia''." ''

BMC Developmental Biology BioMed Central (BMC) is a United Kingdom-based, for-profit scientific open access publisher that produces over 250 scientific journals. All its journals are published online only. BioMed Central describes itself as the first and largest open ...

'' 10:74. . * Photo of trochophore ( figure 2A). *
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Brusina S., 1865: ''Conchiglie dalmate inedite''; Verhandlungen der Kaiserlich-königlichen Zoologisch-botanisch Gesellschaft in Wien 15: 3–42

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]
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: 161–180 14 (1889): 75–81]
Affenzeller S., Haar N. & Steiner G. (2017). Revision of the genus complex Gibbula: an integrative approach to delineating the Eastern Mediterranean genera Gibbula Risso, 1826, Steromphala Gray, 1847, and Phorcus Risso, 1826 using DNA-barcoding and geometric morphometrics (Vetigastropoda, Trochoidea). Organisms Diversity & Evolution. 17(4): 789-812
{{Commons category, Steromphala varia varia Gastropods described in 1758 Taxa named by Carl Linnaeus