''Rossiteria nucleolus'' 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). ''Rossiteria nucleolus'' (Pilsbry, 1903). 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=547289 on 2012-11-23

Description

The height of the shell attains 5.6 mm, its diameter 6.3 mm. The narrowly umbilicateshell has a depressed globose-conic shape. Its color pattern is white with an interrupted buff zone above, and conspicuously variegated with squarish black-brown spots, of which there is a row of broad ones below the suture (three or four on a whorl), a row of smaller ones just above the periphery, and another one on the base. Besides these, there is an irregular articulation or dotting of dark brown on the spiral cords. The glossy surface is sculptured with numerous very low and subequal, nearly smooth spiral threads, almost obsolete on the base, but reappearing on the border of the umbilicus. The surface shows, under a lens, subregular, close, longitudinal grooves, almost obsolete, but visible near the suture and umbilicus. 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 convex. 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. The

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 oblique. The columellar margin is deeply concave in the middle. The columella is abruptly truncate at the base. The outer lip is bevelled to a sharp edge, thickened and spirally lirate within.H. Pilsbry, ''New Japanese Mollusks''; The Nautilus XVII # 5, p. 70
(described as ''Monilea (Rossiteria) nucleolus'')

Distribution

This marine species occurs off

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

H. Pilsbry, New Japanese Marine Mollusca:Gastropoda; Proceedings of the Academy of Natural Sciences of Philadelphia. vol. 56 (1904); pl. VI # 58, 58a
* Poppe G.T., Tagaro S.P. & Dekker H. (2006) ''The Seguenziidae, Chilodontidae, Trochidae, Calliostomatidae and Solariellidae of the Philippine Islands''. Visaya Supplement 2: 1-228. page(s): 111

External links

Encyclopedia of Life

World Register of Marine Species
{{Taxonbar, from=Q7369857

nucleolus The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of sig ...

Gastropods described in 1903