''Coelotrochus tiaratus'', whose common names include tiara top shell, brown top shell, mititi, and mitimiti 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). ''Coelotrochus tiaratus'' (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=598204 on 2012-11-23

Description

The shell grows to a length of 18 mm. The depressed conical shell is very deeply false-umbilicate and rather thin. The

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

has convex outlines;. The

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex ...

is acute, and lemon yellow when eroded. The 5 to 5½

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 nearly planulate, but the upper margin of each whorl is prominent and projecting beyond the periphery of the preceding. 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 carinated at the periphery. The

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 ...

above consists of spiral lirae, about 5 to 8 on each whorl, cut into close oblique beads. The interstices are obliquely finely striate, one or two of the broader ones usually with a central riblet. The color of the shell is whitish or yellowish, finely tessellated or articulated with reddish brown The tessellations are formed by the disintegration of narrow radiating stripes, which are on the base frequently continuous. The base of the shell is nearly flat, with seven or eight concentric close fine lines, which are crenulated in a peculiarly irregular manner by distinct short oblique impressed marks. The interstices are finely radiately striate. The subrhomboidal

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 smooth within. The

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

is oblique, nearly straight, with an obsolete, scarcely perceptible fold above, inserted upon the side of the umbilicus, not in its center. The smooth umbilical area is white or yellow. The false-umbilicus is deep and narrow, but partly filled by a white callus, not tapering to a point. Specimens from rocky shores are often eroded and encrusted with coralline algae, while those from shell, gravel, or cobble substrata are usually clean. Primarily a grazer of hard surfaces, most abundant among beds of bivalves. Also occurs in tidal channels at the mouths of harbours, where it grazes over empty shells of pipis.Cook, Steve De C., “New Zealand Coastal Marine Invertebrates Vol 1”, Canterbury University Press, NZ 2010, ISBN 978-1877257-60-5

Distribution

This marine shell occurs off

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

and the

Chatham Islands The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about te ...

subtidally down to 30m, in a range of habitats.

References

* Gray, J.E. (1835). Catalogue of shells collected on the east coast of New Zealand, by the Rev. W. Yate. Appendix, pp 307–310 in: Yate, W., An account of New Zealand; and of the formation and progress of the Church Missionary Society's mission in the northern island. Seeley & Burnside, London. * Powell, A.W.B. 1979: ''New Zealand Mollusca: Marine, Land and Freshwater Shells''. Collins, Auckland 500p (p. 58) * Marshall, B.A., 1998. ''A review of the Recent Trochini of New Zealand (Mollusca: Gastropoda: Trochidae)''. Moll. Res.1, 19:73-106 * Maxwell, P.A. (2009). Cenozoic Mollusca. Pp 232-254 in Gordon, D.P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch.

External links

To World Register of Marine Species
*
Quoy J.R.C. & Gaimard J.P. (1832-1835). Voyage de découvertes de l'"Astrolabe" exécuté par ordre du Roi, pendant les années 1826-1829, sous le commandement de M. J. Dumont d'Urville. Zoologie. 1: i-l, 1-264; 2(1): 1-321 [1832
2(2): 321-686 [1833]; 3(1): 1-366 [1834]; 3(2): 367-954 [1835]; Atlas (Mollusques): pls 1-93 [1833]. Paris: Tastu]
Cossmann, M. (1918). Essais de paléoconchologie comparée. Onzième livraison. Paris: published by the author. 388 pp., 11 plates

Philippi, R. A. (1846). Diagnoses testaceorum quorundam novorum. Zeitschrift für Malakozoologie. 3: 97-106

Hutton, F.W. (1883). Description of some new Tertiary shells from Wanganui. Transactions and Proceedings of the Royal Society of New Zealand. 1882: 410-411

Bruce A. Marshall, ''Molluscan and brachiopod taxa introduced by F. W. Hutton in The New Zealand journal of science''; Journal of the Royal Society of New Zealand, Volume 25, Issue 4, 1995
{{Taxonbar, from=Q5140704 tiaratus Gastropods described in 1834