''Seguenzia monocingulata'' is an extinct

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 ...

Seguenziidae Seguenziidae is a family of very small deepwater sea snails, marine gastropod mollusks in the superfamily Seguenzioidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).Bouchet, P. (2012). Seguenziidae. Accessed through ...

. It resembles '' Seguenzia formosa'' and has been regarded as a synonym of that (extant) species. However the two species are distinct, based on shell morphology.

Description

The height of the shell attains 4 mm. The white, imperforate shell has a high conoid shape. The

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 have revolving ribs, of which the last has about four distant prominent ones, besides minor striae on the base.

Distribution

This species was originally described by Seguenza from

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Trapani Trapani ( , ; scn, Tràpani ; lat, Drepanum; grc, Δρέπανον) is a city and municipality (''comune'') on the west coast of Sicily, in Italy. It is the capital of the Province of Trapani. Founded by Elymians, the city is still an impor ...

, a locality of the city of Messina, Sicily. Dautzenberg, Ph.; Fischer, H. (1906). Mollusques provenant des dragages effectués à l'ouest de l'Afrique pendant les campagnes scientifiques de S.A.S. le Prince de Monaco. Résultats des Campagnes Scientifiques Accomplies sur son Yacht par Albert Ier Prince Souverain de Monaco, XXXII. Imprimerie de Monaco: Monaco. 125 p., 5 plates
/ref> It is common in deep-sea deposits from southern Italy.

References

External links

* {{DEFAULTSORT:Seguenzia Monocingulata monocingulata Gastropods described in 1876 Prehistoric gastropods