''Asthelys simplex'' is a
species of extremely small deep water
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
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
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* ...
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 in the
family 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 ...
.
[Rosenberg, G. (2012). ''Asthelys simplex'' (Watson, 1879). Retrieved through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=492405 on 2013-04-14]
Description
The shell grows to a height of 6.5 mm. The shell is a rather narrow flat-based cone that is sharply angulated. The shell is small, thin, delicate, smooth, glassy, and nacreous under a thin white calcareous surface.
Sculpture: There are longitudinals, which are faint, hairlike and sinuated, showing the old lines of growth. The whole surface has traces of faint, rounded, and irregular spirals. At the bottom of each
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 ...
is a flat puckered band about 0.25 mm. broad, whose upper edge projects sharply, especially on the upper whorls, and whose lower edge is a slight narrow flange, which forms a sharp carina at the periphery. This band forms the upper border of the
suture, which is further marginated below by two not continuous rounded threads occupying the top edge of each whorl. The base of the shell is covered by about fourteen rounded ridges and furrows, which are rather stronger toward the center, the last one, forming the edge of the
umbilicus, being specially so.
Color: The surface is a dead slightly creamy white, formed by a thin calcareous layer through which the underlying nacre shines.
The
spire is high and conical. The
apex broken. The 8 whorls (reckoning the first two as broken) show a slow and regular increase till the last, which enlarges rapidly. They are perfectly flat, with an upper and lower border, sharply angulated and carinated at the periphery, slightly convex but still very flat on the base, with a blunted angulated and carinated umbilical edge. The suture is linear, almost invisible, marginated above and below. The
aperture is perpendicular, rhomboidal, with the
columella and basal edges nearly equal, and the columella and outer
lip nearly parallel. The outer lip is sharp and thin, not patulous, not descending, advancing at its junction with the
body whorl
The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk.
In gastropods
In gastropods, the b ...
, then retreating so as to form the broad open sinus, acute angled at the periphery, slightly arched across the base, nicked close to the point of the pillar. The columellar lip is arched, strengthened by a thin pad; reverted on the umbilicus so as to leave a slight groove behind it, it has a slight tooth in front. From the body whorl it bends very much over to the left, so as largely to cover the umbilicus, and then it curves over to the right to join the outer lip on the base at an obtuse angle. The umbilicus is small, oblique edged, funnel-shaped, nearly covered by the columellar lip, contracted within, scored with hair-like lines of growth.
Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
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Distribution
This species occurs off the mouth of La Plata
La Plata () is the capital city of Buenos Aires Province, Argentina. According to the , it has a population of 654,324 and its metropolitan area, the Greater La Plata, has 787,294 inhabitants. It is located 9 kilometers (6 miles) inland from th ...
, Uruguay at a depth of 3,500 m.
References
External links
Biodiversity Heritage Library (1 publication)
Encyclopedia of Life
World Register of Marine Species
{{Taxonbar, from=Q13401341
simplex
In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions. The simplex is so-named because it represents the simplest possible polytope in any given dimension. ...
Gastropods described in 1879