''Aliculastrum exaratum'' is a species of

gastropods Gastropods (), commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and from the land. Ther ...

belonging to the family

Haminoeidae Haminoeidae, commonly known as the haminoeid bubble snail family, is a taxonomic family of sea snails, marine opisthobranch gastropod mollusks in the superfamily Haminoeoidea. The name of this family has long been controversial, and used to be ...

Description

The length of the shell attains 6.8 mm, its diameter 3.3 mm. (Original description in Latin) A small, elliptical, and compressed shell with a narrow, elongated

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

. The shell is brown, encased in a thin epidermis. It is finely grooved in a spiral pattern with lines that vary in spacing and tend to fade towards the middle. 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. Spire ...

is shallowly umbilicated, with the interior marked by distinct transverse striations. The outer

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

is extended posteriorly, while the inner lip mimics an umbilical slit as it approaches the

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

. (Description as ''Atys chimera'') The shell is elongate-ovoid, with a shining, translucent, white appearance. Growth lines are pronounced, especially near the outer lip, with approximately nine incised spiral lines posteriorly and around sixteen anteriorly. These lines are separated by a narrow, clear band above the middle of the shell and are unequally spaced, becoming closer toward the extremities. The shell is obliquely truncate at the top, with the apex being narrowly and falsely umbilicated. The growth lines are prominently visible, dipping deeply into the cavity. The aperture is as long as the shell, featuring a well-rounded notch or posterior siphonal canal where the outer lip rises from the edge of the false umbilicus. The aperture is narrow for the first three-fifths, then widens sharply. The outer lip is subangulate above, and slightly convex as it runs nearly parallel with the upper portion of the inner lip, joining the sharply convex and slightly effuse basal lip. The columella is nearly straight in its lower part, sharply concave above, with a strong callus that is reflexed to partially cover the deep and moderately large umbilicus, extending thinly over the lower portion of the inner lip.

Distribution

The marine species occurs off

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

, Mexico and the Pacific coast of Central America.

References

External links

* exaratum Gastropods described in 1857 {{Heterobranchia-stub