''Pleurotomella benedicti'' 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
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
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
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 Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
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 ...
.
Description
The length of the shell attains 17 mm, its diameter 8 mm.
(Original description) The fusiform shell is moderately stout, with a high, regularly tapered
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 are ...
, and very convex, shouldered
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 ...
s. These have strong, oblique, transverse ribs rendered nodulous by well-developed, raised cinguli. The shell contains six whorls, below the chestnut-colored
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 called ...
. The suture is deep, not very oblique. The subsutural band is rather broad, concave, nearly smooth, contrasting strongly with the rest of the whorls. Its
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 ...
consists only of the deeply concave lines of growth, parallel with the notch in the outer
lip. Below the subsutural band the whorls are abruptly swollen, forming a rounded shoulder. The transverse ribs, commencing at the shoulder, are prominently raised, rather oblique, and extend entirely across the whorls of the spire, becoming smaller next the suture. On 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 ...
they extend to the base of the
siphonal canal
The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...
. They are obtuse at summit and separated by wider, deeply concave interspaces. On the last whorls there are about sixteen ribs. Both the ribs and interspaces are crossed by well-marked, somewhat unequal, raised, revolving lines, separated by narrow grooves. These, in passing over the ribs, produce small, somewhat conical, unequal nodules, which give a somewhat rough appearance to the surface of the shell. One of the spiral lines just above the suture and one or two of those at the shoulder are stronger than the rest. Between the ribs the revolving lines are roughened by fine lines of growth. The four nuclear whorls are evenly rounded and in strong contrast with those that follow them. The first one is very minute, forming a very acute
apex. The surface is finely cancellated by two sets of lines running obliquely in opposite directions. 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 opt ...
is elongated and rather broad in the middle. The outer lip has a deep and broad posterior sinus, below which it projects strongly forward and is regularly arched to the base of the siphonal canal. The canal is narrow, nearly straight, slightly prolonged. The
columella is straight and tapered, with its inner edge forming a slightly sinuous curve. The
inner lip is smooth and polished, with a thin coat of enamel which extends somewhat forward in a regular curve on the body whorl. The color is white with a pale grayish tinge, with the exception of the whorls in the protoconch, which are deep chestnut-brown.
Distribution
''P. benedicti'' can be found in Atlantic waters, ranging from the coast of
south to the
Lesser Antilles
The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc betwe ...
.
[Tunnell, John W., Jr., Felder, Darryl L., & Earle, Sylvia A., eds. ''Gulf of Mexico Origin, Waters, and Biota, Volume 1: Biodiversity.'' Texas A&M University Press, 2009. 668.]
References
External links
*
{{DEFAULTSORT:Pleurotomella Benedicti
benedicti
Gastropods described in 1884