''Seguenzia cervola'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of extremely small deep-water

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Seguenziidae Seguenziidae is a family (biology), family of very small deepwater sea snails, marine (ocean), marine gastropod mollusks in the superfamily Seguenzioidea (according to the Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), taxonomy of the Gastr ...

.Rosenberg, G. (2013). ''Seguenzia cervola'' Dall, 1919. Retrieved through:

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=492451 on 2013-06-10

Description

(Original description by W.H. Dall) The height of the shell attains 4.5 mm. The white shell is small and slightly depressed. It has one small, smooth nuclear

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). In nature File:Photograph and axial plane floral diagra ...

and five subsequent whorls. These are flattened a little in front of a distinct suture. They are separated by a somewhat convex smooth fasciole from a thread-like keel above the periphery. In front of this is a wide, smooth interval. On the base of the shell are about a dozen spiral threads with wider interspaces, and very faint microscopic spiral striae are visible in all the interspaces under a lens. On the upper whorls, there is a small thread between the keel and the suture. Near the

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...

, they become obsolete. At the

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

, is a shallow sulcus between the keel and the suture and a smaller one at the middle of the base. There is a sharp notch below the end of the thin, arcuate projecting

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

, behind which is a moderately large twisted umbilicus. The body shows no glaze. The base of the shell is conspicuously convex.Dall (1919) Descriptions of new species of Mollusca from the North Pacific Ocean; Proceedings of the U.S. National Museum, vol. 56 (1920)
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Distribution

The type specimen of this marine species was found off the Coronado Islands, Baja California.

References

External links

Biodiversity Heritage Library (2 publications)

Encyclopedia of Life

USNM Invertebrate Zoology Mollusca Collection

ITIS

World Register of Marine Species

Encyclopedia of Life

USNM Invertebrate Zoology Mollusca Collection

World Register of Marine Species
{{Taxonbar, from1=Q3709825, from2=Q14326692 cervola Gastropods described in 1919