''Aforia trilix'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

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

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Cochlespiridae Cochlespiridae is a taxonomic family of predatory sea snails, marine gastropod mollusks in the superfamily Conoidea. This family is not well differentiated morphologically, and there is poor congruence between the molecular and shell characters. ...

Description

(Original description) The high, very narrow shell has a biconically fusiform shape. It is subscalar, bicarinated, strong, and white. The axial

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 ...

features numerous unequal, strong, harsh, flexuous lines of growth, with occasional lines that are stronger than the rest. The spiral sculpture displays two keels: the upper and stronger keel is slightly above the middle of the

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). In nature File:Photograph and axial plane floral diagra ...

s, sharply pinched out but with a rounded edge. There is a drooping, straight-lined shoulder above, and the whorl is somewhat contracted below it, giving it considerable prominence. The lower keel is a rounded, rather prominent thread that stands out due to the contraction of the whorl below it into the suture. Between these two keels, roughly in the middle, lies a thread more pronounced than the others. Coarse, unequal, and interrupted threads closely cover the entire surface. Two or three of these threads, in line with the sinus on the shoulder between the upper keel and the suture, are somewhat stronger, more regular, and swollen than the rest. The surface is almost free of spiral threads just below this point, where the lines marking the lower edge of the sinus run. The shell is porcellanous white. The epidermis is extremely thin, smooth, and pale yellowish. 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 high, narrow, and subscalar. The

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...

consists of 1¼ embryonic whorls, which are globose, smooth, and slightly obliquely pressed down on one side at the extreme point. The 7½ whorls are narrow and angulated, with a straight, drooping shoulder below the suture, slightly concave between the keels, and contracted into the lower suture. The base is conical and projects on the right side into a long, narrow, somewhat twisted snout. The suture is a fine, sharp, deeply impressed line. The

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 ...

is club-shaped, being oval above with a sharp angulation at the upper point, and prolonged into a long, relatively narrow, but slightly widening

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 i ...

, which is open due to the oblique cutting away of the columellar lip. 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 thin, sharp, and patulous, with a slight contraction at the edge of the siphonal canal. It leaves the body nearly at a right angle and advances with a very slight convexity to the keel. Above the keel lies a deep, thin-lipped, U-shaped sinus, whose lower margin is parallel to, but slightly above, the conical thread. From the keel, the lip's edge is first convex and then slightly receding at the front, while on the side, it is first convex and then concave to the point of the snout, where it becomes very straight. The columellar lip has a thin, porcellaneous glaze that spreads slightly on the body, from which the spirals are cut somewhat away. The lip is slightly concave above, then straight, and early and obliquely cut away at the front of 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 ...

, where it is slightly prominent, finally running out to the point of the snout as a thin edge bordering the siphonal canal. R.B. Watson, Mollusca of H.M.S. ‘Challenger’ Expedition.—Part X; Journal of the Linnean Society of London, Zoology Volume 15, Issue 88, pages 457–475, November 1881

Distribution

This species is found in the Southern Indian Ocean between

Kerguelen The Kerguelen Islands ( or ; in French commonly ' but officially ', ), also known as the Desolation Islands (' in French), are a group of islands in the sub-Antarctic region. They are among the most isolated places on Earth, with the closest t ...

and

Heard Island The Territory of Heard Island and McDonald Islands (HIMI) is an Australian external territory comprising a volcanic group of mostly barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall land ...

References

External links

Griffiths, H.J.; Linse, K.; Crame, J.A. (2003). SOMBASE - Southern Ocean mollusc database: a tool for biogeographic analysis in diversity and evolution. Organisms Diversity and Evolution. 3: 207–213
{{DEFAULTSORT:Aforia Trilix trilix Gastropods described in 1881