''Gymnobela atypha'' is a species 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 ...

Raphitomidae Raphitomidae is a family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet P. & Rocroi J.-P. (Ed.) (2005). "Classification and nomenclator of gastropod families". ''Malacologia'' 47(1-2). . 39 ...

.MolluscaBase (2019). MolluscaBase. Gymnobela atypha (Bush, 1893). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=532893 on 2019-04-25

Description

The length of the shell attains 36 mm, its diameter 12 mm. (Original description) The rather large shell is solid, somewhat translucent, bluish white, with a comparatively smooth surface and little lustre. The

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 ...

is unusually high, consisting of nine angularly shouldered whorls below the small, very acute, chestnut-brown protoconch. 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 short and broad. The posterior sinus is as broad as the subsutural band and rather shallow. The outer

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

is considerably inflated, curving gradually toward 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 ...

without forming a decided siphonal canal. The columella is nearly straight, curved slightly anteriorly, with a narrow, closely adhering strip of enamel. The suture is distinct, undulating and slightly channelled. The subsutural band is rather broad, oblique, somewhat concave, ornamented on the upper whorls with hue, distinct, curved riblets and lines of growth, the latter alone being visible on the two lower whorls. Just above the periphery, at the edge of the subsutural band, very narrow, sharp, slightly raised, oblique ribs, separated by very wide, slightly concave spaces, cross the whorls to the suture, and on the body whorl disappear just below the sutural line of the

. These ribs are most conspicuous at the shoulder, and vary considerably in different specimens, changing from the above narrow, sharp ones, with wide interspaces, to others broad and rounded, With narrower interspaces, the number on the body whorl vary from twelve to fifteen. The entire surface, except the protoconch and the subsutural band, is cut by fine, shallow grooves separated by flattened spaces of unequal width. These are deeper and coarser, or broader, on the lower part of the body whorl and siphonal canal, causing the spaces between them to appear as raised rounded threads. The protoconch is long, very slender, consisting of four and a half finely reticulated light chestnut-brown whorls. The apical whorl is imperfect, but must have been very minute, judging from the size of the succeeding one. Bulletin of the Museum of Comparative Zoology at Harvard College v. 23 (1892-1893)

Distribution

This marine species was found off the Carolinas, USA.

References

* K.J. Bush (1883), Bulletin of the Museum of Comparative Zoology 23: 205, pl. 2, fig. 3 * Figueira R.M. Andrade & Absalão R.S. (2012) ''Deep-water Raphitomidae (Mollusca, Gastropoda, Conoidea) from the Campos Basin, southeast Brazil.'' Zootaxa 3527: 1–27.

External links

* atypha Gastropods described in 1893 {{Gymnobela-stub