''Ethalia guamensis'', common name the Guam button 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 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). ''Ethalia guamensis'' (Quoy & Gaimard, 1834). 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=547307 on 2012-11-23 The subspecies ''Ethalia guamensis selenomphala'' Pilsbry, 1905 is a taxon inquirendum.

Description

The length of the shell varies between 10 mm and 25 mm. The depressed, polished shell is perforate, solid, strong, and smooth. Its color is whitish, mottled and lineolate above with brown, reddish, fawn-color or purplish, with 4 narrow spiral articulated lines, sometimes scarcely visible because of the variegated coloration. The color of the base is lighter. There are six

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, convex, the last one rounded and convex beneath. The suture is impressed. 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 outer wall is moderately thick. The columella is strong and thick, arcuate above, spread upon 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 ...

and nearly over the umbilicus in a pad of callus, which is either white, pink or deep crimson. The callus is kidney-shaped, but slightly convex, filling the umbilicus except a narrow chink. From the outer termination of the callus an arcuate groove extends to the base of the columella, within which the surface of the shell is radiately finely striate and darker colored. Ethalia guamensis - radula

Radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

: The teeth, especially those of the central part are very thin and transparent, without distinct cusps; the rhachidian tooth (R) is broadly winged, bow-shaped, at its upper part it is thickened, a true cusp cannot be detected. The first (i), second (2), third (3) and fourth (4) laterals are about equal in shape. The first one is subtriangular, with a slightly concave inner and convex outer margin, thickened at its upper part, the second is very similar, the third is narrower and the fourth is more subquadrangularly elongate; the fifth (5) or last lateral is club-shaped, thickened above, without cusp. Of the uncini (U) the proximal one has a short, broad cusp, with a small denticle near the base of the distal margin; the second is more elongate, also with a small denticle; the subsequent ones are much more elongate, No denticles can be detected, perhaps because the cusps lie so close together, as to cover each other in part.Schepman 1908-1913, The Prosobranchia of the Siboga Expedition; Leyden,E. J. Brill,1908-13
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Distribution

This marine species occurs off

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...

, 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 ...

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

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

References

* Adams, A. 1855. ''A monograph of Umbonium (Rotella), a genus of Trochidae''. Proceedings of the Zoological Society of London 1853(21): 187-189 * Hedley, C. 1907. ''The Mollusca of Mast Head Reef, Capricorn Group, Queensland, part II.'' Proceedings of the Linnean Society of New South Wales 32: 476-513, pls 16-21 * Schepman, M.M. 1908. ''Prosobranchia (excluding Heteropoda and parasitic Prosobranchia). Rhipidoglossa and Docoglossa. With an appendix by Prof. R. Bergh ectinobranchiata'' Siboga-Expéditie Report 49(1): 1-108, 9 pls * Yen, T.C. 1942. ''A review of the Chinese gastropods in the British Museum''. Proceedings of the Malacological Society of London 24(5/6): 170-290 * Abbott, R.T. & Dance, S.P. 1982. ''Compendium of Seashells: a colour guide to more than 4,200 of the world's marine shells''. New York : E. P. Dutton pp. i-x, 1-411. * Wilson, B. 1993. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, Western Australia : Odyssey Publishing Vol. 1 408 pp.

External links

Barcode of Life (1 barcode)

Biodiversity Heritage Library (18 publications)

Encyclopedia of Life

GenBank (3 nucleotides; 1 proteins)

World Register of Marine Species
* {{Taxonbar, from=Q5402845 guamensis Gastropods described in 1834