''Polyspirella trachealis'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

of sea snail, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

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 es ...

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 ...

Pyramidellidae Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs. The great majority of species of pyrams are micr ...

, the pyrams and their allies.Bouchet, P. (2011). ''Polyspirella trachealis'' (Gould, 1861). Accessed 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 list of names of marine organisms. Content The content of the registry is edited and maintained by scientific speciali ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=580496 on 2012-01-12

Description

The yellowish-white shell has an elongate-conic shape. Its length varies between 5.7 mm and 12.2 mm. 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 flo ...

s of the

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also calle ...

are large, planorboid, smooth and well rounded. They are obliquely immersed in the first of the succeeding turns, above which only the tilted edge of the last two volutions projects. The twelve whorls of the

teleoconch The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. So ...

are moderately rounded. They are shouldered at the summit, and marked by three strong spiral cords which slope abruptly posteriorly and gently anteriorly. These cords are about twice as wide as the spaces that separate them. Beginning with the third to last turn, the suture falls gradually more and more anterior to the periphery, exposing a portion of the base, which appears as a flattened band above the suture. In addition to the spiral cords, the whorls are marked by numerous, slender, raised, axial threads in the depressed spaces between the cords. These threads are about one-fourth as wide as the spaces that separate them. The suture is scarcely differentiated from the other grooves. The periphery of the body whorl is well rounded. The base of the shell is rather short, and well rounded. It is marked by incremental lines and exceedingly fine, spiral striations. 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 broadly ovate. The posterior angle is acute. The outer lip is thin, showing the external

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

within. The

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 ...

is somewhat twisted. It is provided with an obsolete fold at its insertion.P. Bartsch (1915), Report on the Turton Collection of South African Marine Mollusks; United States National museum, bulletin 91 p. 82 (described as ''Turbonilla (Cingulina) trachealis'')

Distribution

The type specimen was found off

Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is ...

, South Africa.

References

* Odé, H. (1998). Indo-Pacific taxa of turbonilids, excluding those along the Americas. Texas Conchologist. 34 (2): 33-103 * Van Aartsen J.J. & Corgan J.X. (1996) South African pyramidellacean gastropod names. Basteria 60: 153-160

External links

To World Register of Marine Species

Gould, A. A. (1861). Description of new shells collected by the United States North Pacific Exploring Expedition. Proceedings of the Boston Society of Natural History. 7: 385-389
Pyramidellidae Gastropods described in 1861 {{Pyramidellidae-stub