''Oxystele'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of sea snails, marine 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

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 ...

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 resemb ...

, the top snails. Although previously suggested as a subgenus of '' Diloma'', genetic analysis has shown it to be more appropriate as its own genus.

Description

The depressed conical shell is dark or variegated in color. 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 ...

is oblique. The concave

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

is arcuate, thin-edged, perfectly simple and curved below. It is above spread over the umbilical area as a rounded, well-defined pad of callus.Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
/ref> Patterns of the variegated shell color within the genus ''Oxystele'' are shown in the image : A–C ''Oxystele variegata'' from Namibia, 5 km north of Swakopmund, diameter 22.2 mm (NMSA E6038) D–F ''Oxystele impervia'' from the Western Cape, Groen Rivier, diameter 22.3 mm (NMSA E7353) G–I ''Oxystele'' sp. from the Eastern Cape, Tsitsikamma National Park, diameter 16.5 mm (HVDBM058-10, NMSA W7371); the colour pattern of these specimens suggests ''Oxystele variegata'', but these specimens group within the unit of ''Oxystele impervia'' J–L ''Oxystele'' sp. from the Northern Cape, Noup, diameter 18.0 mm (HVDBM185-10, NMSA W7608); the colour pattern suggests ''Oxystele impervia'', but they group with ''Oxystele variegata''

Distribution

These marine species occur off

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

and Japan.

Species

Patterns of shell colour within the genus Oxystele - ZooKeys-365-337-g004

Phylogram (weighted maximum parsimony based on 16S, COI and

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sequence data) of the species in the genus ''Oxystele'': Other species in the genus not included in this tree are: * '' Oxystele fulgurata'' (Philippi, 1848) * ''

Oxystele merula ''Oxystele merula'' is a species of sea snail, a marine gastropod mollusk in the family (biology), family Trochidae, the top snails.Bouchet, P. (2013). Oxystele merula (Dillwyn, 1817). Accessed through: World Register of Marine Species at http: ...

'' (Dillwyn, 1817) Species brought into synonymy: * ''Oxystele capensis'' (Gmelin, 1791): synonym of ''

Oxystele sinensis ''Oxystele sinensis'', common name the pink-lipped topshell, is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails. Description The size of the shell varies between 18 mm and 51 mm. Distribu ...

'' (Gmelin, 1791) * ''Oxystele depressa'' Granata-Grillo, 1877: synonym of ''

Tomura depressa ''Tomura'' is a genus of sea snails, marine gastropod mollusks in the 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 purp ...

'' (Granata-Grillo, 1877) * ''Oxystele impervius'' Menke, Schwarz, 1910: synonym of '' Oxystele variegata'' (Anton, 1838) * ''Oxystele inflata'' Turton, 1932: synonym of ''

'' (Gmelin, 1791) * ''Oxystele romettensis'' Granata-Grillo, 1877: synonym of '' Cirsonella romettensis'' (Granata-Grillo, 1877) * ''Oxystele sagittifera'' Lamarck, Smith, 1903: synonym of '' Oxystele variegata'' (Anton, 1838) * ''Oxystele sagittifera'' var. ''perdix'' Koch in Turton, 1932: synonym of '' Oxystele tigrina'' (Anton, 1838) * ''Oxystele sagittifera'' var. ''rufanensis'' Turton, 1932: synonym of '' Oxystele variegata'' (Anton, 1838) * ''Oxystele tabularis'' var. ''pulchra'' Turton, 1932: synonym of '' Oxystele variegata'' (Anton, 1838) * ''Oxystele tigrinus'' Turton 1932: synonym of '' Oxystele tigrina'' (Anton, 1838) * ''Oxystele zonata'' Wood, Sowerby, 1892: synonym of '' Gibbula zonata'' (Wood, 1828)

References

* Williams S.T., Donald K.M., Spencer H.G. & Nakano T. (2010) ''Molecular systematics of the marine gastropod families Trochidae and Calliostomatidae (Mollusca: Superfamily Trochoidea)''. Molecular Phylogenetics and Evolution 54:783-809 {{Taxonbar, from=Q7116153 Trochidae Taxa named by Rodolfo Amando Philippi Gastropod genera