''Infundibulum concavum'' 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 ...

Trochidae The Trochidae, common name top-snails or top-shells, are a family of various sized sea snails, marine gastropod molluscs in the subclass Vetigastropoda. This family is commonly known as the top-snails because in many species the shell resembles ...

, the top snails.

Description

The height of the shell varies between 35 mm and 40 mm, and its diameter ranges from 45 mm to 47 mm. The shell is false-umbilicate and has a regularly conic shape, being concave on the underside. Its color is greenish and roseate under a dull grayish-green cuticle. The outlines of 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 ...

are nearly rectilinear. The 7 to 8

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 are planulate, very obliquely striate, radiately corrugated, and covered with a very minute secondary sculpture of fine, close, radiating wrinkles. The

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, 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 ...

is acutely carinated at the periphery. The base of the shell is concave and concentrically lirate, with about 6 to 8 lirae that are granose in the young and nearly smooth in the adult. The aperture is very oblique, covering half the base. 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 very prosocline and crenulated by the folds on the outside. The basal margin is straight, thin, and simple. The columella is oblique, with a strong fold above, projecting into 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 ...

with a very deep insertion. The parietal wall is lirate. The umbilical tract is white or yellowish, spirally costate in young and smooth in fully adult specimens. This is a very distinct form, with an aperture so oblique that it resembles a ''

Calyptraea ''Calyptraea'', commonly known as the Calyptraea chinensis, Chinese hat snails is a genus of sea snails, marine (ocean), marine gastropod mollusks in the family (biology), family Calyptraeidae, a family which contains the slipper snails or slippe ...

'' Lamarck, 1799 H. Pilsbry, Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
(described as ''Trochus concavus'' )

Distribution

This species occurs in the Indian Ocean off

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

and the

Mascarene The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their na ...

Basin.

References

External links

* {{DEFAULTSORT:Infundibulum concavum concavum Gastropods described in 1791 Taxa named by Johann Friedrich Gmelin