''Tosatrochus attenuatus'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

of sea snail in the subfamily

Cantharidinae The Cantharidinae are a taxonomic subfamily of very small to large sea snails, marine gastropod molluscs in the family Trochidae, common name top snails.Bouchet, P.; Gofas, S. (2011). Cantharidinae. Accessed through: World Register of Marin ...

of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

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. It is the only species in the genus ''Tosatrochus''.

Description

The length of the shell varies between 20 mm and 25 mm. The thick, imperforate or very narrowly perforate shell has a conic-elongated shape. It is whitish, ornamented with radiating livid-brown flammules, brown punctulate. The 9

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 flo ...

s are convex, spirally lirate (the lirae unequal) and longitudinally nodose-costate, the nodules more prominent below. The sutures are impressed. The angulated body whorl is depressed beneath the sutures and nodulous at the periphery. It is very convex and with about 8 concentric lirae beneath, the interstices with intercalated lirulae. 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 ...

is subquadrate and canaliculate within. The basal margin is arcuate and plicate. 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 ...

is subangular, concave, strongly truncate at base, with a short callus over the

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy * ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus urbis Romae The ...

.Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
(described as ''Cantharidus elongatus'')

Distribution

This species occurs in the Indo-West

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

and off 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 ...

and

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 ...

References

{{Taxonbar, from1=Q7827556, from2=Q7827557 Trochidae Monotypic gastropod genera