''Roseaplagis rufozona'' is a species of

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 Trochidae, the top snails.

Description

The length of the shell varies between 4 mm and 8 mm. The small, rather thin, imperforate shell has a globosely conoidal shape. Its sculpture consists of distant rounded spiral cinguli, 5 on the penultimate, 13 on 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 ...

with smooth interstices. Its colour is white or cinereous. The spiral riblets are rufous or pinkish brown. The spire is conoidal with an acute apex. The sides are slightly convex. The small

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 conic with about 2

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. These are convex and spirally lirate, mostly eroded. The spire contains about 5 whorls, the body whorl rather large, and rounded at the periphery The base of the shell is convex. The suture is impressed. The subquadrangular aperture is iridescent and lirate within. The outer lip slightly indented, sharp, articulated with pinkish-brown, with an inner opaque white band. The white columella is vertical, with a slight tubercle in the middle, often obsolete. The inner lip has a small expansion beyond the columella, but perfectly filling up the perforation. There is a thin white callus on the parietal wall.

Distribution

This marine species is endemic to and occurs off

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

, New Zealand.

References

* Powell, A.W.B. 1979: N''ew Zealand Mollusca: Marine, Land and Freshwater Shells''. Collins, Auckland 500p (p. 56) * Marshall, B.A. 1998: ''The New Zealand Recent species of Cantharidus Montfort, 1810 and Micrelenchus Finlay, 1926 (Mollusca: Gastropoda: Trochidae)''. Molluscan Research 19: 107-156 (p. 140) * Donald K. & Spencer H. G. (2016). ''Phylogenetic patterns in New Zealand and temperate Australian cantharidines (Mollusca: Gastropoda: Trochidae: Cantharidinae): trans-Tasman divergences are ancient.'' Molecular Phylogenetics and Evolution. 100: 333-344. {{Taxonbar, from1=Q61697760, from2=Q8010778 rufozona Gastropods described in 1853