The Mount Pirri isthmus rat (''Isthmomys pirrensis'') is a species of

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

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 almost 608 species, it is the second-largest family of mammals, and h ...

. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

is subtropical or

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

moist lowland

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

s. It is found only in

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...

. At the time of its discovery, it was considered as the “most common rat of southeastern Panama”. Found only in the eastern region of Darien, ''I. pirrensis'' appears to be a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

species confined to the Panamanian side of the Serrania del Darien. Its occurrence on the Colombian side of the Serrania has been suggested without documentation of specimens. Although neotomine-peromyscine rodents have historically been the subject of systematic research, studies involving ''Isthmomys'' have generally excluded ''I. flavidus'' due to its rarity in museum collections and the unavailability of tissue samples for molecular analysis. In addition, morphological and physiological studies involving ''I. flavidus'' used specimens from the Cerro Hoya locality which was originally proposed as a geographic race of ''I. pirrensis''.(Handley 1966).

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. Isthmomys Rodents of Central America Mammals described in 1912 Taxonomy articles created by Polbot {{Cricetidae-stub