''Turbonilla macra'' 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 ...

of sea snail, a 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 ...

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.WoRMS (2011). ''Turbonilla macra'' Dall & Bartsch, 1909. 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 specialis ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=576058 on 2012-03-01Keen M. (1971). Sea shells of Tropical West America. Marine mollusks from Baja California to Perú. (2nd edit.). Stanford University Press pp. 1064

Description

The very small shell is subcylindric in the middle, tapering rapidly at the

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

. Its length measures 3.2 mm. The early whorls are wax-yellow, the later ones white, with a very broad, wax-yellow band at the periphery, which extends above the sutures and on the base. The whorls of the protoconch are very small, and number at least two. They form a depressed helicoid

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 a ...

, which is obliquely half immersed in the first of the succeeding turns. The seven 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. Some ...

are moderately rounded at first, later flattened. They are ornamented by almost straight, vertical, slender, well-developed axial ribs, of which there are 22 upon the first, 24 upon the second to fifth, and 25 upon the penultimate turn. The intercostal spaces about as wide as the ribs, marked by five equal but not equally spaced series of spiral pits. The first four of these above the periphery are equally spaced; the fifth is a little nearer to the summit of the whorl than its neighbor. The sutures are well impressed. The periphery of the body whorl is well rounded. It is marked by the feeble continuations of the axial ribs. The base of the body whorl is prolonged, and well rounded. it is marked by six equally spaced and equally strongly incised spiral lines. 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 ovate. The posterior angle is acute. The outer lip is thin, showing the external markings 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 wo ...

is moderately strong, reinforced by the base, and provided with a weak fold at its insertion. The parietal wall is covered with a thin callus.Dall & Bartsch (1909), A Monograph of West American Pyramidellid Mollusks, United States National Museum Bulletin 68, p.91
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Distribution

The type specimen was found in the Pacific Ocean off Point Abreojos, Baja California Peninsula.

References

External links

To USNM Invertebrate Zoology Mollusca Collection

To USNM Invertebrate Zoology Mollusca Collection

To World Register of Marine Species
{{Taxonbar, from=Q7854333 macra Gastropods described in 1909