Smith's vole is a species of rodent

Rodent

Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

 in the family Cricetidae

Cricetidae

The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...

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

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

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This vole is named after Richard Gordon Smith

Richard Gordon Smith

Richard Gordon Smith was a British traveler, sportsman and naturalist who traveled through many countries in the late nineteenth century and lived in Japan for a number of years.thumb|Illustration from Ancient Tales and Folklore of Japan-Life:...

, (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 species of this vole.

Taxonomy

There has been considerable discussion as to the phylogeny

Phylogenetics

In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...

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

Distribution

Smith's vole is found on the Japanese islands of Dogo

Dogo, Shimane

Dōgo is the largest of the Oki Islands in the Sea of Japan, north of the Shimane peninsula . The largest city is Okinoshima.-By airplane:Japan Airlines offers two flights per day from Itami Airport, located in Osaka....

, Honshu

Honshu

is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...

, Kyushu

Kyushu

is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....

 and Shikoku

Shikoku

is the smallest and least populous of the four main islands of Japan, located south of Honshū and east of the island of Kyūshū. Its ancient names include Iyo-no-futana-shima , Iyo-shima , and Futana-shima...

. Also at Oki

Oki

-Places:*Oki District, Shimane - the Oki Islands in Japan, formerly Oki Province*Oki, Fukuoka - a town in southern Japan*Oki Islands - a group of islands in the Sea of Japan*Oki Airport - The airport serving the Oki Islands...

 and four cities and one town in the region of Mikawa

Mikawa Province

is an old province in the area that today forms the eastern half of Aichi Prefecture. It was sometimes called . Mikawa bordered on Owari, Mino, Shinano, and Tōtōmi Provinces....

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Description

The colour 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 20 and 35 grams. The fur is dense and short, the muzzle blunt and the ears rounded. The dental formula 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.