''Clionella subventricosa'' 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 ...

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

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 ...

Clavatulidae Clavatulidae is a Taxonomy (biology), taxonomic family (biology), family of sea snails, marine gastropod mollusks in the superfamily Conoidea. The family is not well differentiated morphologically. Clavatulidae was raised, based on cladistic an ...

. ;Subspecies: * ''Clionella subventricosa kaffraria'' Kilburn, 1985 (Eastern Cape subspecies) * ''Clionella subventricosa subventricosa'' (E. A. Smith, 1877)

Description

The shell grows to a length of 22 mm. The ovate, rather dark brown shell has a squat, fusiform shape. The eight

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 slightly convex. The spiral

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 ...

shows shallow, well-spaced grooves. The axial ribs are rounded and number 11-14 per whorl. The shoulder angle lies below the middle of the whorl. The periphery is flattened so that

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 weakly biangulate. 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 rather large with a rather narrow, slightly notched

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 ...

. The color inside the aperture shows various shades of pale brown. The anal sinus is very shallow.Smith, E.A. (1877)
"Diagnoses of new Species of Pleurotomidae in the British Museum"
''The Annals and Magazine of Natural History: Including Zoology, Botany, and Geology''. vol. xix. p. 499.

Distribution

This marine species occurs from

False Bay False Bay (Afrikaans: ''Valsbaai'') is a body of water in the Atlantic Ocean between the mountainous Cape Peninsula and the Hottentots Holland Mountains in the extreme south-west of South Africa. The mouth of the bay faces south and is demarc ...

Cape Agulhas Cape Agulhas (; , "Cape of Needles") is a rocky headland in Western Cape, South Africa. It is the geographic southern tip of Africa and the beginning of the traditional dividing line between the Atlantic and Indian oceans according to the In ...

, South Africa

References

* Kilburn, R.N. (1985). ''Turridae (Mollusca: Gastropoda) of southern Africa and Mozambique. Part 2. Subfamily Clavatulinae''. ''Annals of the Natal Museum'' 26(2), 417–470 * Steyn, D.G. & Lussi, M. (1998) ''Marine Shells of South Africa. An Illustrated Collector's Guide to Beached Shells''. Ekogilde Publishers, Hartebeespoort, South Africa, ii + 264 pp. page(s): 150

External links

* {{Taxonbar, from=Q3719916 Endemic molluscs of South Africa subventricosa Gastropods described in 1877