''Pyrgulina alveata'' 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 ...

of very small

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 pyramidellid

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 ...

micromollusk A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also ...

. This genus is currently placed in the subfamily

Chrysallidinae Chrysallidinae is a taxonomic group of very small sea snails, marine gastropod mollusk in the family Pyramidellidae, the pyrams and their allies. Taxonomy Chrysallidinae has been one of eleven recognized subfamilies of the gastropod family ...

of 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 ...

Pyramidellidae Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs. The great majority of species of pyrams are micromol ...

.OBIS : ''Pyrgulina lecta''
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Description

The elongate-ovate shell is turreted, shouldered, sutures crenulated, shining, hyaline to milk-white. It measures 3.4 mm. The nuclear

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 ...

moderately' large, deeply obliquely immersed in the first of the succeeding whorls, only the last half turn of the last volution is visible from the side. The six post-nuclear whorls are rather high between the sutures, somewhat flattened, the summit of the succeeding whorls falls a little anterior to the periphery of the preceding one. This gives the whorls a constricted appearance at the suture. The whorls are ornamented by strong sublamellar axial ribs, which are thickened and cuspid at the summit. Fourteen of these ribs occur upon the first, sixteen upon the third, and twenty upon the penultimate whorl. The intercostal spaces are broad and rounded, fully three times the width of the ribs, crossed by narrow, incised spiral lines, which are about one-fourth as wide as the space enclosed between them. Twelve of these lines occur between the sutures upon the fourth and penultimate whorls. The periphery and the base of 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 ...

are well rounded, the latter attenuated. They are marked like the space between the sutures by the prominent continuations of the axial ribs and ten incised strong, spiral lines. 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 suboval. The columella is short, curved, reinforced by the attenuated base, provided with a strong, oblique fold near its insertion. The parietal wall is covered by a moderately thick callus, which extends over the umbilical area.Dall & Bartsch, ''Notes on Japanese, Indo-Pacific and American Pyramidellidae''; Proceedings of the U.S. National Museum, vol XXX n° 1452; 1906

Distribution

This species occurs in the Pacific Ocean off

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

References

External links

{{Taxonbar, from=Q7263550 Pyramidellidae Gastropods described in 1906