''Hirasea acutissima'' 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 ...

of small air-breathing

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known as ...

, a

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

pulmonate Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...

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

Charopidae Charopidae is a taxonomic family of small air-breathing land snails (and semi-slugs such as ''Otoconcha dimidiata''), terrestrial pulmonate gastropod mollusks in the superfamily Punctoidea.MolluscaBase eds. (2021). MolluscaBase. Charopidae Hutt ...

. The width of the shell is 2 mm. The height of the shell is 4 mm. ''H. acutissima'' is

endemic Endemism is the state of a species being found 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 found elsew ...

Haha-jima , native_name_link = , image_caption = Map of the Hahajima Rettō (Imōtojima is mislabeled as Tori-shima) , image_size = , pushpin_map = Japan complete , pushpin_label = Hahajima , pushpin_label_position = , pushp ...

in the

Ogasawara Islands The Bonin Islands, also known as the , are an archipelago of over 30 subtropical and tropical islands, some directly south of Tokyo, Japan and northwest of Guam. The name "Bonin Islands" comes from the Japanese word ''bunin'' (an archaic readi ...

, Japan, and is listed as endangered in the ''

IUCN Red List of Threatened Species 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 the world's most comprehensive inventory of the global conservation status of biologi ...

''. In 2007, the species was rediscovered after being considered to be extinct.Chiba S., Davison A. & Mori H. (2007) "Endemic Land Snail Fauna (Mollusca) on a Remote Peninsula in the Ogasawara Archipelago, Northwestern Pacific". ''

Pacific Science ''Pacific Science'' is a quarterly multidisciplinary peer-reviewed scientific journal covering the biological and physical sciences of the Pacific basin, focusing especially on biogeography, ecology, evolution, geology and volcanology, oceanograph ...

'' 61(2): 257–265. .

References

Endodontidae Molluscs of Japan Natural history of the Bonin Islands Endemic fauna of Japan Extinct animals of Japan Taxonomy articles created by Polbot {{Endodontidae-stub