''Roseaplagis artizona'' 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 ...

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.

Description

The height of the shell attains 3.5 mm, its diameter 4 mm. The very small shell is subperforate or imperforate. It has a conical shape. It is slightly iridescent and shining. 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 ...

consists of fine spiral lirae, about 15 on the penultimate whorl. The growth lines are inconspicuous. It has a light yellow colour with radiate oblique broad streaks of dark brown. The intervals are filled with a few light brown dots. The base of the shell is tessellated with yellowish and brown. The epidermis is very thin, the pearly inner layer shining partly through it. 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 ...

is conic with its height greater than that of 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 ...

. The sides are very slightly convex. The

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

is small, acute, and consists of two convex, light-brown, and finely spirally striate

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. The six whorls are flatly 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 keeled at the periphery. The base of the shell is convex. The sutures are very little impressed. The slightly oblique

is subquadrangular. The interior is silvery and finely lirate. The outer and basal

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

are sharp, angled where they meet, margined with a white bead. 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 subvertical, slightly arched, with a slight swelling in the middle. The umbilicus is partly or completely covered by the columella expansion. The white umbilical tract is slightly impressed. Suter H. (1913-1915), Manual of New Zealand Mollusca; Wellington, N. Z. :J. Mackay, govt. printer,1913-1915
(described as ''Gibbula micans'')

Distribution

This marine species is endemic to

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 ...

References

* Adams, A. 1853. ''Contributions towards a monograph of the Trochidae, a family of gasteropodous Mollusca''. Proceedings of the Zoological Society of London 19 1851: 150-192. * Powell, A.W.B. 1979: ''New Zealand Mollusca: Marine, Land and Freshwater Shells''. Collins, Auckland 500p * Marshall B.A. 1998. ''The New Zealand Recent species of Cantharidus Montfort, 1810 and Micrelenchus Finlay, 1926 (Mollusca: Gastropoda: Trochidae).'' Molluscan Research 19(1): 107-156 {{Taxonbar, from1=Q28950211, from2=Q7990178 artizona Gastropods of New Zealand Gastropods described in 1853