''Microdrillia circumvertens'' is a species of

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 ...

Borsoniidae Borsoniidae is a monophyletic family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet, P. (2011). Borsoniidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/ ...

.WoRMS (2015). Microdrillia circumvertens (Melvill & Standen, 1901). In: MolluscaBase (2015). Accessed through: World Register of Marine Species at http://marinespecies.org/aphia.php/aphia.php?p=taxdetails&id=434400 on 2016-03-14

Description

The height of the small, milky-white shell attains 6 mm, its width 2.25 mm. It has an ovate-fusiform shape. It contains 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. 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 bicarinate. A very beautiful spirally carinate and lirate species. The short canal and wide sinus proclaim it rightly placed in ''Microdrillia'' and the acute carinae are peculiar. 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 oblique and oblong. 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 ...

contains no plications.Melvill & Standen (1901) Mollusks from the Persian Gulf and Arabian Sea; Proceedings of the Zoological Society of London. v. 2, 1901
/ref>

Distribution

This marine species occurs from the

Gulf of Oman The Gulf of Oman or Sea of Oman ( ''khalīj ʿumān''; ''daryâ-ye omân''), also known as Gulf of Makran or Sea of Makran ( ''khalīj makrān''; ''daryâ-ye makrān''), is a gulf in the Indian Ocean that connects the Arabian Sea with th ...

Transkei Transkei ( , meaning ''the area beyond Great Kei River,

he river The He River is a tributary of the Xi River in Guangxi and Guangdong provinces in China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it ...

Kei''), officially the Republic of Transkei (), was an list of historical unrecognized states and dependencies, unrecognised state in the southeastern region of South Africa f ...

, South Africa

References

External links

Bouchet P., Kantor Yu.I., Sysoev A. & Puillandre N. (2011) A new operational classification of the Conoidea. Journal of Molluscan Studies 77: 273–308
circumvertens Gastropods described in 1901 {{Borsoniidae-stub