''Clanculus microdon'' 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.Bouchet, P. (2012). ''Clanculus microdon'' A. Adams, 1853. 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=547257 on 2012-11-23 The variety ''Clanculus microdon'' var. ''ater'' Pilsbry, 1901 is accepted as '' Clanculus ater'' Pilsbry, 1901.

Description

The size of the shell attains 17 mm. The thick, solid shell has a depressed conoidal shape. It is of a reddish-brown hue, interstices between the ribs, chocolate colored, above marked with a few broad yellowish or flesh-tinted maculations radiating from the sutures toward, but not quite reaching the periphery, which with the base, has the ribs sparsely dotted with white. The spire is low-conic with a roseate apex. The suture is distinct and not canaliculate. The five

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 are moderately convex. They are encircled by lirae more or less distinctly granulate, very unequal in size, numbering about 14 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 ...

. The interstices are closely obliquely striate, and usually bearing a minute central riblet. The body whorl descends anteriorly and is rounded at the periphery. The base of the shell is convex, with revolving lirae more superficially and much more closely cut into granules than those of the upper surface, and also broader, flatter, and equal in size. These number 6 to 7, one or two around the umbilicus. The umbilicus is white, dotted with yellow or reddish, the remainder reddish-brown, sparsely articulated on the ribs with white, sometimes radiately marked with narrow white stripes. 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 somewhat contracted and subcircular. The outer and basal lips are thickened and finely crenulated within. The columella is oblique, with a tooth-like fold above, solute, and deeply inserted upon the side of the umbilicus The middle portion is concave, with a reflexed subdenticulate edge, ending beneath in a minute denticle. The profound umbilicus is smooth and polished within, bordered by a strong rib bearing 6 or 7 projecting white teeth, the upper one the largest. This is a species belonging to the group of C. atropurpureus, C. bathyrhaphe, etc., including species in which the base of the columella is scarcely toothed, but passes into the basal margin in a regular curve, bearing several subequal denticles. The columella above is inserted upon the side of the umbilicus instead of in the center of the axis as in the typical ''Clanculus (Clanculopsis)'' Monterosato, 1880. From ''

Clanculus atropurpureus ''Clanculus atropurpureus'' is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.Bouchet, P. (2012). ''Clanculus atropurpureus'' (Gould, 1849). Accessed through: World Register of Marine Species at http: ...

'', which seems to be its nearest ally, ''Clanculus microdon'' differs in the larger size, variegated coloration, and irregularity of the spiral ribs on the upper surface.H. Pilsbry, Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
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Distribution

This species occurs off the

Andaman Islands The Andaman Islands () are an archipelago in the northeastern Indian Ocean about southwest off the coasts of Myanmar's Ayeyarwady Region. Together with the Nicobar Islands to their south, the Andamans serve as a maritime boundary between th ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

and the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

References

External links

Biodiversity Heritage Library (11 publications)

Encyclopedia of Life

GenBank (4 nucleotides; 1 proteins)

World Register of Marine Species
* {{Taxonbar, from=Q5125694 microdon Gastropods described in 1853