''Shutonia variabilis'' 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 ...

, a marine

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 in the family

Pseudomelatomidae Pseudomelatomidae is a family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda ( Bouchet & Rocroi, 2005). In 1995 Kantor elevated the subfamily Pseudomelatomina ...

, the turrids and allies.

Description

The length of the shell attains 18.5 mm, its diameter 6 mm. (Original description) The elongately fusiform shell has a long

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...

. it is thin and yellowish-white. The shell contains eight

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, of which about 2 (if normal) form a smooth, slightly inflated, reddish-brown

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 ...

. The subsequent whorls are subangular, concave in their upper part and separated by a conspicuous waved suture. The sculpture consists of a row of tubercles at the periphery, sharper in upper whorls, more obtuse lower on, a row of granules, just below the suture, becoming scarcely visible in last whorl and entirely or nearly wanting in some specimens. The lower part of the whorls show one or two rather faint, spiral lirae. The part of the last whorl below the keel shows more or less conspicuous spirals, which vary from regular flat lirae to more irregular riblike ones. In the latter case mainly two spirals are stronger. Moreover, there are extremely fine spiral striae and rather conspicuous growth-striae. The aperture is elongated and angular above. The peristome is thin, with a wide sinus above, then protracted. The columellar margin is nearly straight, only slightly concave above, ending in a rather long, narrow siphonal canal, covered with a thin layer of enamel. The interior of the aperture is smooth.Schepman, 1913. The prosobranchia of the Siboga expedition. Part IV -V - VI: Toxoglossa

Distribution

This marine species occurs off Indonesia and in the

Andaman Sea The Andaman Sea (historically also known as the Burma Sea) is a marginal sea of the northeastern Indian Ocean bounded by the coastlines of Myanmar and Thailand along the Gulf of Martaban and west side of the Malay Peninsula, and separated from ...

and off Thailand.

References

* Schepman, M. 1913. p. 425 Six specimens out of ten from Schepman 1913 were identified as ''Makiyamaia sibogae'' by Shuto 1970].

External links

*
Gastropods.com: ''Shutonia variabilis''
{{DEFAULTSORT:Shutonia Variabilis variabilis Gastropods described in 1913