''Calassomys apicalis'' is the only

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Calassomys'', a

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 Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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 lives in the east of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Taxonomy

This species was originally described, at the same time as its genus, in 2014 by the

zoologists This is a list of notable zoologists who have published names of new taxa under the International Code of Zoological Nomenclature. A * Abe – Tokiharu Abe (1911–1996) * Abeille de Perrin, Ab. – Elzéar Abeille de Perrin (1843–1910) * ...

Ulyses F. J. Pardiñas, Gisele Lessa, Pablo Teta, Jorge Salazar-Bravo and Edeltrudes M. V. C. Câmara. ; Type locality The type locality is located 3.25 km northeast of Macacos, Pedreira do Gaio, in the state of

Minas Gerais Minas Gerais () is one of the 27 federative units of Brazil, being the fourth largest state by area and the second largest in number of inhabitants with a population of 20,539,989 according to the 2022 Brazilian census, 2022 census. Located in ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. ; Exemplar type The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

is catalogued as MCN / PUC-MG 2785, an adult male (clase desgaste dental 3) (dental wear class 3) of which its skull, part of its postcranial skeleton, and skin (in good condition) have been preserved. Karyotype, suspended cells and tissues were preserved in alcohol. It was collected by E. Câmara and C. Guimarães Costa in November, 2006. ; Etymology

Etymologically Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

, the generic name ''Calassomys'' is an

eponym An eponym is a noun after which or for which someone or something is, or is believed to be, named. Adjectives derived from the word ''eponym'' include ''eponymous'' and ''eponymic''. Eponyms are commonly used for time periods, places, innovati ...

referring to A. Calaça de Espírito Santo, the father of one of the authors ( Edeltrudes M. V. C. Câmara). The specific name ''apicalis'' is derived from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

and alludes to the animal's characteristic white-tipped tail. ; Characterization and phylogenetic relations It is possible to differentiate this rodent by several characteristics, such as its elongated tail, in which the distal 2.5 to 5 cm are entirely white. Its skull has a domed profile with a long face, and notably small molars. Small, vestigial mesolophs and mesostyles are found on the upper first and second molars (a unique feature within Phyllotini). Phylogenetic analyses based on nuclear and mitochondrial molecular markers showed that this taxon is the sister of the remaining genera of the tribe Phyllotini indicating that its diversity has expanded towards the northeast, and that an ancient tribal diversification event occurred in eastern Brazil.

Geographic distribution and habitat

This species of rodent 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 eastern

, and specifically the

Espinhaço Mountains The Espinhaço Mountains (, ) are a mountain range in Brazil. The range runs roughly north and south through the states of Minas Gerais and Bahia, extending for approximately . It forms the divide between the upper watershed of the São Francisco ...

, in Sempre Vivas National Park, at altitudes greater than 1000m above sea level.

References

{{Authority control Phyllotini Endemic mammals of Brazil Rodents of South America Taxa described in 2014 Monotypic rodent genera