''Selastele retiarium'', common name the netted top shell, 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 ...

Calliostomatidae Calliostomatidae is a family of sea snails within the superfamily Trochoidea and the clade Vetigastropoda.Gofas, S. (2013). Calliostomatidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetail ...

Description

(Original description by Hedley & May) The height of the shell attains 7 mm. The small, subperforate shell has a conical shape with sharply keeled periphery, overlapping spire

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 ...

s and a flat base. Its colour and number of whorls are uncertain, the latter exceeding six.

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 ...

: small spiral threads parted by wider interstices amount to seven on the penultimate, and to twenty 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 ...

. Of these a double row compose the peripheral keel. On either side of the keel the interstices are wider than usual. The radials are irregular oblique wave-like folds, twenty-two on the body whorl, which raise beads on the keel rows, and there cease abruptly. On the base incipient radials bead the inner spirals. 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 trapezoidal. The simple outer lip is sharply angled by the periphery. The columella insertion is a little reflected over the minute umbilicus.Hedley & May (1908), Mollusca from one hundred fathoms, seven miles east of Cape Pillar, Tasmania; Records of the Australian Museum v. 7 (1908)
(described as ''Calliostoma retiarium'')

Distribution

This marine species occurs off

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

, Victoria and

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

at depths between 170 m and 180 m.

References

* Cotton, B.C. (1959). South Australian Mollusca. Archaeogastropoda. Adelaide : Govt. Printer. pp. 1–449 * Wilson, B. (1993). ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, WA : Odyssey Publishing. Vol.1 1st Edn pp. 1–408. * Marshall, B.A. (1995). ''Calliostomatidae (Gastropoda: Trochoidea) from New Caledonia, the Loyalty Islands and the northern Lord Howe Rise''. pp. 381–458 in Bouchet, P. (ed.). Résultats des Campagnes MUSORSTOM, Vol. 14 . Mém. Mus. nat. Hist. nat. 167 : 381–458

External links

* {{DEFAULTSORT:Selastele Retiarium retiarium Gastropods described in 1908