''Pilsbryspira umbrosa'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Pseudomelatomidae Pseudomelatomidae is a family (biology), family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda (Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), Bouchet & Ro ...

Description

The length of the shell attains 12 mm, its diameter 4 mm. (Original description) The small, narrow shell has a fusiform shape and is of rude

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 ...

. It is dusky-brown with a rufous tinge over the

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, 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 ...

and orifice. The shell contains 7-8

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). In nature File:Photograph and axial plane floral diagra ...

s (the nepionic being imperfect in the specimens seen), the remainder longitudinally furnished with obtusely-rounded, strong, and frequent ribs, say about fourteen on the body whorl. All the whorls are ventricose, impressed, and spirally plainly ridged suturally, and crossed by strongly developed spirals, swollen and almost becoming nodulous at the points of junction with the costae. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is small and ovate. The outer

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

is slightly expanded. The sinus is wide but 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 i ...

is very short. The columellar margin is oblique. Proceedings of the Malacological Society of London v. 14-15 (1920-1923)
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Distribution

This marine species occurs off

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

References

External links

Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1–1295
umbrosa Gastropods described in 1923 {{Pseudomelatomidae-stub