''Belomitra pacifica'' 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 ...

mollusc 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 esti ...

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 ...

Belomitridae.MolluscaBase eds. (2020). MolluscaBase. Belomitra pacifica (Dall, 1908). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=490760 on 2020-03-29

Description

The length of the (decollate) shell is 23 mm, its diameter 7 mm. (Original description) The small, delicate shell is white with a pale yellowish periostracum. It contains at least six

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 beside the (lost)

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

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 ...

is acute, slender and is longer than 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 ...

. The suture is deep and appressed. The whorls are gently rounded. The apical whorls show (on the third whorl about fifteen) very narrow, sharp, threadlike, vertical ribs with much wider interspaces, and at the suture numerous, irregular, small, retractive folds extending over the fasciole, with wider interspaces, nearly twice as many as there are ribs. On the succeeding whorls these ribs and folds grow sparser and weaker, so that on the sixth whorl ribs, folds and fasciole are obsolete or absent. On the spire, the axial sculpture is crossed by (on the third whorl about eight, on the sixth ten or a dozen) fine flat threads with wider interspaces, (increasing by interpolation), which override the ribs and rise above them but do not form nodules at the intersections. These spirals are very uniform and 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 ...

extend forward covering 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 ...

, and are slightly scored by the incremental lines. The aperture is oval, not mature in the specimen. 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 obsolete. The columella and the body are polished, the surface erased, not callous. The columella is short, gyrate, the axis pervious, but the siphonal canal is short, rather wide, with no siphonal fasciole. The outer lip is only slightly produced, sharp and thin in the type specimen. The operculum is concentric, pointed in front, with an apical nucleus. W.H. Dall (1908) Reports on the Mollusca and Brachiopoda, Bulletin of the Museum of Comparative Zoology at Harvard College. vol. 43

Distribution

This marine species occurs off the

Alexander Archipelago The Alexander Archipelago (russian: Архипелаг Александра) is a long archipelago (group of islands) in North America lying off the southeastern coast of Alaska. It contains about 1,100 islands, the tops of submerged coastal m ...

, Prince Of Wales Island, West of, Alaska, United States, North Pacific Ocean at a depths of 2869 m.

References

* W.H. Dall, Bull. Mus. Comp. Zool. 43(6): 213,270, pl. 12, fig. 3. * Bouchet P. & Warén A. (1986 1985" ''Mollusca Gastropoda: Taxonomical notes on tropical deep water Buccinidae with descriptions of new taxa''. Mémoires du Muséum National d'Histoire Naturelle, A, 133: 457-517

External links

Kantor Yu.I., Puillandre N., Rivasseau A. & Bouchet P. (2012) Neither a buccinid nor a turrid: A new family of deep-sea snails for Belomitra P. Fischer, 1883 (Mollusca, Neogastropoda), with a review of Recent Indo-Pacific species. Zootaxa 3496: 1–64

Tucker, J.K. 2004 ''Catalog of recent and fossil turrids (Mollusca: Gastropoda)''. Zootaxa 682:1-1295.
Belomitridae Gastropods described in 1908 {{Caenogastropoda-stub