''Clionella subcontracta'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

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

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Clavatulidae Clavatulidae is a taxonomic family of sea snails, marine gastropod mollusks in the superfamily Conoidea. The family is not well differentiated morphologically. Clavatulidae was raised, based on cladistic analysis, from subfamily to the family ...

Description

The size of an adult shell varies between 8 mm and 1 mm. The dark yellowish-brown shell is elongate but has a narrow base. It contains eight whorls; the first two are convex, the others concave on top, convex below. The whorls are thus strongly constricted below the suture. The suboval aperture measures about ⅓ the total length of the shell. The

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

is well rounded at the middle and then contracted below. The almost straight axial ribs number 13–16 per whorl. A spiral striation or groove at the periphery, which also winds up the spire just above the suture, is usually more strongly marked than the rest. The

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 is ...

is not notched.Smith, E. A. 1904. On a collection of marine shells from Port Alfred, Cape Colony. 1. Malac. 11 (2): 21-44
(described as ''Drillia subcontracta'') The characteristics of the shell - the small size, the glossy brown shell and the lack of variation - make ''Clionellla subcontracta'' an atypical species within the genus ''Clionella.''

Distribution

This marine species occurs off Namaqualand to

Port Alfred A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Ha ...

, South Africa.

References

* Kilburn, R.N. (1985). ''Turridae (Mollusca: Gastropoda) of southern Africa and Mozambique. Part 2. Subfamily Clavatulinae''. Ann. Natal Mus. 26(2), 417–470. {{DEFAULTSORT:Clionella Subcontracta Endemic fauna of South Africa subcontracta Gastropods described in 1904