''Pleurotomella orariana'' is a
species 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 in the
family 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 12 mm, its diameter 5 mm.
(Original description) The small shell is fusiform. It is white or pale yellowish on a dull surface. Its
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 ...
is eroded and is followed by about six subsequent
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. The suture is distinct, not appressed. The whorls are rounded. The anal fasciole is smooth except for minute arcuate, elevated, more or less distant axial lines, and the intervening incremental lines. The whorl in front of the fasciole is axially sculptured with (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 ...
about twenty-six) moderately strong, equal, rounded, somewhat protractive ribs with subequal interspaces. The ribs extend from the shoulder to the suture or, on the body whorl, to the base, where they become obsolete. These ribs are crossed on the
spire by about six prominent spiral threads, subequal and with wider interspaces, often with a more minute intercalary thread, the primaries somewhat swollen on the summits of the ribs. On the body whorl the same
sculpture extends over the whorl and upon 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 ...
. The outer
lip is thin, broadly arcuate, simple, with a rounded, shallow,
anal sulcus The anal sulcus, also called the anal sinus or anal canal, in Gastropods is a notch, a shelly tube at the top of the aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and fo ...
close to the suture. The body shows a thin wash of callus, white and smooth. The
columella is straight, rapidly attenuated in front with a pervious axis. The siphonal canal is wide, slightly recurved.
W.H. Dall (1908) Reports on the Mollusca and Brachiopoda, Bulletin of the Museum of Comparative Zoology at Harvard College. vol. 43
/ref>
Distribution
This marine species occurs in the Gulf of Panama.
References
External links
*
Dall W.H. (1919). ''Descriptions of new species of mollusks of the family Turritidae from the west coast of America and adjacent regions.'' Proceedings of the United States National Museum. 56(2288): 1-86, pis 1-24
McLean J.H. (1971). A revised classification of the family Turridae, with the proposal of new subfamilies, genera, and subgenera from the eastern Pacific. The Veliger. 14(1): 114-130
{{DEFAULTSORT:Pleurotomella Orariana
orariana
Gastropods described in 1908