''Agathotoma aculea'' 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 Mangeliidae

Description

The length of the shell attains 6 mm, its diameter 2 mm. (Original description) The small shell is purple-brown, banded with white, or varicolored. 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 ...

consists of loosely coiled, smooth

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 teleoconch comprises four additional whorls. The axial sculpture features six somewhat sigmoid, rounded, light-colored ribs that extend continuously up the spire. The interspaces between these ribs are excavated and much wider, with fine axial striation that slightly wrinkles the spirals. The spiral sculpture displays numerous sharp, often paired grooves separated by wider, flattened interspaces, faintly marked by axial striation. The aperture is narrow and accounts for about one-third of the shell's total length. The

anal sulcus The anal sulcus, also called the anal sinus or anal canal, in Gastropods is a notch, a shelly tube at the top of the aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and fo ...

is conspicuous. The outer lip is thickened and smooth inside. The columella is simple, and the

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 ...

is barely differentiated. Dall (1919) Descriptions of new species of Mollusca from the North Pacific Ocean; Proceedings of the U.S. National Museum, vol. 56 (1920)
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Distribution

This marine species was found off Cape San Lucas and

Magdalena Bay Magdalena Bay ( es, Bahía Magdalena) is a long bay in Comondú Municipality along the western coast of the Mexican state of Baja California Sur. It is protected from the Pacific Ocean by the unpopulated sandy barrier islands of Isla Magdalen ...

, Baja Californica

References

Bouchet P., Kantor Yu.I., Sysoev A. & Puillandre N. (2011) ''A new operational classification of the Conoidea''. Journal of Molluscan Studies 77: 273-308.

Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1-1295
{{Taxonbar, from=Q4691565 aculea Gastropods described in 1919 Molluscs of Mexico