''Clanculus johnstoni'' 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 Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

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 ...

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.Rosenberg, G. (2012). ''Clanculus johnstoni'' Hedley, 1917. Accessed through:

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialist ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=594197 on 2012-11-23

Description

The height of the shell attains 6 mm, its major diameter also 6 mm. The small, solid shell has a globose-conic shape. It has a carmine colour with radial buff dashes, about eight to a

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). Whorls in nature File:Photograph and axial plane floral ...

, reaching from the suture half-way to the periphery. The umbilicus and the bordering funicle is white. As in allied forms, there is a colour dimorphism in which olive brown replaces the carmine, a trace of which remains on the summit. The shell contains five whorls. On the penultimate whorl there are four spirals, the upper being a double bead row, and a fifth half-buried in the suture by the succeeding whorl. On 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 ...

there are thirteen spirals which become taller, broader, more widely spaced and more inclined to break up into beads as they ascend from base to suture. The oblique

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

is finally ascending. Within the outer lip are about a dozen entering ridges, the lowest larger than the rest. The oblique columella is twisted, the edge reflected, with a large tooth at the base and a small one above. The umbilical margin broadly overreaches the cavity, its edge with three or four denticules. A translucent callus unites the lips.Hedley, C. 1917. ''Description of a new shell from Caloundra''. Proceedings of the Royal Society of Queensland 29: 55-56
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Distribution

This marine species is endemic to Australia and occurs at intertidal depths off the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

and

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

References

* Wilson, B. 1993. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, Western Australia : Odyssey Publishing Vol. 1 408 pp. * Jansen, P. 1995. ''A review of the genus Clanculus Montfort, 1810 (Gastropoda: Trochidae) in Australia, with description of a new subspecies and the introduction of a nomen novum''. Vita Marina 43(1-2): 39-62

External links

Biodiversity Heritage Library (1 publication)

World Register of Marine Species
{{Taxonbar, from=Q5125680 johnstoni Gastropods of Australia Gastropods described in 1917