''Mikadotrochus beyrichii'', common name Beyrich's slit shell, 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 ...

Pleurotomariidae Pleurotomariidae, common name the "slit snails", is a family of large marine gastropods in the superfamily Pleurotomarioidea of the subclass Vetigastropoda. This family is a very ancient lineage; there were numerous species in the geological pas ...

. It was discovered by Franz Martin Hilgendorf in an ancient Japanese collection.

Description

The size of the shell varies between 50 mm and 100 mm. The shell has a trochiform shape. It is as high as broad. It has a flat base. It shows moderately numerous spiral lines. It is pale yellow, beautifully flamed with 11 red

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 that are regularly increasing. The penultimate whorl has 8 lirae above, 2 in and 2 under the slit fasciole. These lirae are beset with weak nodules, about 3 times as long (in the direction of the spiral) as high or broad. 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 ...

has a blunt angle at its base. This base contains 20 concentric lirae, and in the middle a deep pit or "false umbilicus". On the outside it is white, on the inside it is pearly. The thick, pearly columellar margin is S-shaped.

Distribution

''M. beyrichii'' is endemic to the coastal waters of

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 ...

.Oliver, A.P.H. (2004). ''Guide to Seashells of the World.'' Buffalo: Firefly Books. 17. and

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

References

* Dautzenberg, Ph.; Fischer, H. (1898). ''Note sur le Pleurotomaria beyrichi''. J. conchyliol. XLVI: 218–224, plate XI * Williams S.T., Karube S. & Ozawa T. (2008) ''Molecular systematics of Vetigastropoda: Trochidae, Turbinidae and Trochoidea redefined''. Zoologica Scripta 37: 483–506

External links

* {{DEFAULTSORT:Mikadotrochus Beyrichii Pleurotomariidae Taxa named by Franz Martin Hilgendorf Gastropods described in 1877