Smith's vole (''Craseomys smithii'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

in the family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At over 870 species, it is either the largest or second-largest family ...

. It is also known as Smith's red-backed vole and is found only in

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 ...

. This vole is named after

Richard Gordon Smith Richard Gordon Smith (1858 – 6 November 1918) was a Great Britain, British traveler, sportsman, and naturalist who traveled extensively in the late 19th century and lived in Japan for a number of years. image:Smith-Monoyuki-White sake.jpg, Illus ...

, (1858–1918) who, after falling out with his wife, traveled the world hunting for animals and keeping a record of his travels and discoveries in eight large leather-bound diaries. He spent some time in Japan where he collected mammals for the British Museum, including the type specimen of this vole.

Taxonomy

There has been considerable discussion as to the

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

of this species. The molars grow continually during the animal's life and because of this trait, it was at one time placed in the genus '' Phaulomys''. However, studies using mitochondrial and nuclear ribosomal DNA have shown that it is closely related to the Japanese and Asian species, ''

Craseomys rufocanus The grey red-backed vole or the grey-sided vole (''Craseomys rufocanus'') is a species of vole. An adult grey red-backed vole weighs 20-50 grams. This species ranges across northern Eurasia, including northern China, the northern Korean Pen ...

'', and the Korean species, '' Craseomys regulus'' and that there is no support for its inclusion in ''Phaulomys''. The ever-growing molars in ''C. smithii'' are now believed to be independently derived from a rooted ''Craseomys'' ancestor

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Japan.Mammal Species of the World
bucknell.edu ''Phaulomys'' is now considered a

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

of ''Craseomys'', and contains this species, the Japanese ''C. andersoni'', and the Korean ''C. regulus'', although the exact

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

remains unsettled.

Distribution

Smith's vole is found on the Japanese islands of

Dogo Dogo may refer to: Dogs * Various molossoid dogs breeds originating in Spanish-speaking regions, including ** the Dogo Argentino ** the Dogo Canario, now known as Presa Canario ** the Dogo cubano, extinct ** the Dogo Español or Alano Español * ...

Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

Kyushu is the third-largest island of Japan's Japanese archipelago, four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa Island, Okinawa and the other Ryukyu Islands, Ryukyu (''Nansei'') Ryukyu Islands, Islands ...

and

Shikoku is the smallest of the List of islands of Japan#Main islands, four main islands of Japan. It is long and between at its widest. It has a population of 3.8 million, the least populated of Japan's four main islands. It is south of Honshu ...

. On Honshu, it is found across the central and southern part of the island, but absent from the northern part.Mammals of Japan
(PDF)Retrieved on 2012-12-27.

Description

The color of Smith's vole varies from brownish-yellow to mid brown with the underparts a paler shade of brown. The body length is about 115 millimetres with a tail about 60 millimetres. The weight varies between . The fur is dense and short, the muzzle blunt and the ears rounded. The

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

is and the molars grow continuously throughout life.

Ecology

Smith's vole lives in forests, plantations and farmland in montane areas above about 400 metres. It is absent from alluvial plains. It makes burrows in leaf litter and prefers damp conditions. It is a common species in chosen habitat but some of its populations are fragmented by road development, land reclamation, dam building and deforestation. The diet is entirely vegetarian and it feeds on the stems and leaves of green plants and on seeds. The breeding season varies in different locations and there may be one or two litters per year, each of one to six young, but usually two or three.

References

*Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore. {{Taxonbar, from=Q1764007 Craseomys Mammals described in 1905 Taxa named by Oldfield Thomas Endemic mammals of Japan Taxonomy articles created by Polbot