The Ryukyu shrew (''Crocidura orii''), also known as Orii's shrew, is a species of

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

in the family Soricidae. This species is

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 the

Amami Islands The The name ''Amami-guntō'' was standardized on February 15, 2010. Prior to that, another name, ''Amami shotō'' (奄美諸島), was also used. is a Japanese archipelago in the Satsunan Islands, which is part of the Ryukyu Islands, and is sout ...

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 ...

and is threatened by

habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

and

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

Taxonomy

Orii's shrew was first described, as a

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of the Dsinezumi shrew (''Crocidura dsinezumi orii''), by Kuroda Nagamichi in 1924; he named it after his collector,

Orii Hyōjirō (15 July 1883 – 27 April 1970) was a Japanese Scientific collection, specimen collector of birds and mammals. At least a hundred new species and subspecies were Species description, described based on the Type (biology), type specimens he col ...

, who had provided the skin and skull of a single male from

Amami Ōshima , also known as Amami, is the largest island in the Amami Islands, Amami archipelago between Kyūshū and Okinawa Prefecture, Okinawa. It is one of the Satsunan Islands, all of which belong to Kagoshima Prefecture, Japan. The island, 712.35 ...

. This

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

, damaged during the initial trapping, was destroyed by fire in 1945. In their 1951 checklist, Ellerman and Morrison-Scott listed the shrew instead as a subspecies of the

Greater white-toothed shrew The greater white-toothed shrew (''Crocidura russula'') is a small insectivorous mammal found in Europe and North Africa. It is the most common of the white-toothed shrews. This species is found along the Mediterranean Sea, Mediterranean, Nethe ...

(''Crocidura russula orii''). In 1961, after the recovery of a second individual from the stomach of a '' hime habu'' or Ryukyu Island pit viper (''Ovophis okinavensis''),

Yoshinori Imaizumi was a Japanese zoologist. He is known for describing the Iriomote cat in 1967. He was the director of the zoological department of the National Museum of Nature and Science. References

1914 births 2007 deaths Japanese mammalogists Japan ...

elevated the shrew to species rank, based on morphological comparison with other species of ''

Crocidura The genus ''Crocidura'' is one of nine genera of the shrew subfamily Crocidurinae. Members of the genus are commonly called white-toothed shrews or musk shrews, although both also apply to all of the species in the subfamily. With over 180 sp ...

''. In 1998, after the study of five further specimens from Amami Ōshima and

Tokunoshima , also known in English as is an island in the Amami archipelago of the southern Satsunan Islands of Kagoshima Prefecture, Japan. The island, in area, has a population of approximately 27,000. The island is divided into three administrative t ...

, confirmed this taxonomic treatment.

Characteristics and Habitat

Orii's shrew is small in size, ranging from 65-90 millimeters on average. The hairs on Orii's shrew may range from a light grey to brown color. These hairs are longer than the hairs of any other species of the ''

'' genus by 2 millimeters on average. The forefeet are large and wide with long claws and the tail is 50-66% of the length of the body on average. Orii's shrew is characterized by having a long mandible, large teeth, and a round forehead. Orii's shrew is endemic to the

. Orii's shrew only inhabits the natural broadleaf forests of the island, however, their morphology leads scientists to believe semi-

fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

habitats would be inhabitable.

Conservation

Only 10 specimens of Orii's shrew have been observed. The species was classified as endangered on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

in 2015 after the population began to decline. This decline is due to the introduction of

mongoose A mongoose is a small terrestrial carnivorous mammal belonging to the family Herpestidae. This family has two subfamilies, the Herpestinae and the Mungotinae. The Herpestinae comprises 23 living species that are native to southern Europe, A ...

s as predators and the removal of natural forest space. Mongooses have migrated to Amami Island and are killing shrews from an already small population The habitat is being degraded and fragmented due to roads being built through the forest. These roads have been continuously built and destroyed over the past 50 years, which continually degraded the environment and displaces the species. Only 15-30% of the natural forests remain intact on Amami Island.

References

{{Taxonbar, from=Q305903 Crocidura Endemic fauna of the Ryukyu Islands Endemic mammals of Japan Endangered fauna of Asia Mammals described in 1924 Taxa named by Nagamichi Kuroda Species that are or were threatened by habitat loss Taxonomy articles created by Polbot