''Cryptogemma polystephanus'' 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 ...

, 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 Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

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 ...

Turridae Turridae is a taxonomic family name for a number of predatory sea snails, marine gastropod mollusks in the superfamily Conoidea. MolluscaBase (2018). Turridae H. Adams & A. Adams, 1853 (1838). Accessed through: World Register of Marine Specie ...

, the turrids.

Description

The length of the shell attains 25 mm. (Original description) The shell of moderate size contains six or more

whorls 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 d ...

. 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 eroded. The shell is white, with a cream-colored

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and ...

. The spiral

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 numerous fine, subequal, flattisb threads with narrower interspaces, which cover the whole shell. To these are added a thickened ridge which borders the anterior margin of the suture, and on 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 ...

a peripheral nodose keel, which is less marked 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 ...

, where it forms the shoulder.oO the penultimate whorl there are twenty of these nodules. Other axial sculpture is furnished by line, short, sharp elevated wrinkles which cross retractively the ridge adjacent to the suture, like the "gathers" of a skirt, and become obsolete on the fasciole. There are twenty-eight of these wrinkles on the margin of the penultimate whorl. The space above the shoulder is distinctly excavated, especially on the spire. Theis suture distinct and, on the earlier whorls, almost Channelled. 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 ...

is ovate. The anal fasciole is comprised in the nodose shoulder, not reaching the suture. The outer lip is arcuately produced forward The columella show a thin, smooth layer of enamel, obliquely attenuated distally, somewhat twisted. 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 wide and shallow. W.H. Dall (1908) Reports on the Mollusca and Brachiopoda, Bulletin of the Museum of Comparative Zoology at Harvard College. vol. 43
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Distribution

This marine species was found off San Cristobal Island, Galapagos Islands, Ecuador, South Pacific Ocean at a depth of 1159 m.

References

External links

* polystephanus Gastropods described in 1908 {{turridae-stub