''Monotygma lauta'' 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 ...

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 ...

, the pyrams and their allies.

Description

The rather stout, milky white shell is subturrited and has a broadly elongate-conic shape. The length of the shell is 7 mm. The

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 of 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 " ...

are small. They are almost completely immersed in the first succeeding whorl. Only the tilted edge of two volutions is apparent, which indicates that the axis of whorls of the protoconch is at right angles to the axis of the later ones. The 6¾ whorls of the

teleoconch The gastropod shell is part of the body of many gastropods, including snails, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium ...

are inflated, strongly shouldered at the summit, and decidedly rounded. They are marked by many weak, irregular axial riblets and very strong, broad, angular, incised, spiral channels. These are crossed by many more or less regularly spaced and subequally developed backward slanting axial riblets. These riblets render the flattened and faintly spirally striated, raised spaces between the incised channels feebly crenulated on both edges. Five incised channels appear between the sutures on the second and third whorl and six on the fourth and fifth. The periphery and the base of 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 ...

are well rounded, the latter sculptured like the space between the sutures, with six spiral channels. The suboval

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 quite large. The posterior angle is obtuse. The thin outer lip is denticulate. The incised spiral channels appear as a chain of squarish areolations within, by transmitted light. The

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

is moderately strong, somewhat twisted and slightly reflected with a subobsolete oblique fold near its insertion. The parietal wall is covered by a very feeble callus.Dall & Bartsch (1906), Notes on Japanese, Indopacific, and American Pyramidellidae; Proceedings of the United States National Museum, 30(1452): 321-369, 10 pls.
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Distribution

This marine species occurs off Japan. It has also been found as a migrant in the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

References

* van Aartsen J.J. & Hori S. (2006). ''Indo-Pacific migrants into the Mediterranean. 2. Monotigma lauta (A.Adams, 1853) and Leucotina natalensis Smith, 1910 (Gastropoda, Pyramidellidae)''. Basteria 70: 1-6 * Templado, J. and R. Villanueva 2010 ''Checklist of Phylum Mollusca''. pp. 148–198 In Coll, M., et al., 2010. The biodiversity of the Mediterranean Sea: estimates, patterns, and threats. PLoS ONE 5(8):36pp {{Taxonbar, from=Q13861700 Pyramidellidae Gastropods described in 1853