''Ithycythara penelope'' 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 5 mm, its diameter 2 mm. (Original description) The minute shell is pale brownish, or whitish with obscure brownish spiral bands. It has a minute trochoid

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 ...

of three

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 earlier smooth, the last axially minutely closely ribbed, followed by five subsequent whorls. The suture is distinct, hardly appressed, the whorl sloping steeply away from it. The; spiral sculpture consists of fine close-set threads over the entire surface. The whorls are moderately convex. The axial sculpture consists of (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 ...

six) prominent ribs, with much wider interspaces, extending the whole length of the whorl and on the spire more prominent at the periphery. The aperture is narrow and parallel-sided. The outer lip is varicose and smooth within. 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 wide and shallow. 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 hardly differentiated.Dall (1919) Descriptions of new species of Mollusca from the North Pacific Ocean; Proceedings of the U.S. National Museum, vol. 56 (1920)

Distribution

This marine species occurs in the Sea of Cortez, Western Mexico, and off the Galápagos Islands

References

External links

Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1–1295.
* {{DEFAULTSORT:Ithycythara Penelope penelope Gastropods described in 1919