''Irenomys tarsalis'', also known as the Chilean climbing mouse,
[ Chilean tree mouse,][ or long-footed irenomys,][Musser and Carleton, 2005, p. 1121] is 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 ...
found in Chile
Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
, from about 36° to 46°S, and in adjacent Argentina
Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
, mainly in forests. It is a large, long-tailed, soft-furred mouse characterized by grooved upper incisor
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
s and specialized molars with transverse ridges, divided by deep valleys, which are connected by a transverse ridge along the midline of the molars.
''Irenomys tarsalis'' is a docile, herbivorous animal that lives in trees. It is so distinct from other species that it was placed in its own 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 ...
, ''Irenomys'', in 1919. The name comes from the Ancient Greek word εἰρήνη (''iren'') meaning "peace
Peace is a state of harmony in the absence of hostility and violence, and everything that discusses achieving human welfare through justice and peaceful conditions. In a societal sense, peace is commonly used to mean a lack of conflict (suc ...
", in reference to the end of World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. Although it has been generally placed in the tribe Phyllotini
The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species c ...
, genetic evidence does not support any close relationships with other genera, so that it is now classified as a member of the subfamily Sigmodontinae
The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species ...
''incertae sedis
or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
'' (of uncertain position).
Taxonomy
In 1900, Rodolfo Armando Philippi
Rodolfo Amando (or Rudolph Amandus) Philippi (14 September 1808 – 23 July 1904) was a German–Chilean paleontologist and zoologist. Philippi contributed primarily to malacology and paleontology, but also published a major work on Diptera of C ...
named both ''Mus tarsalis'' (from Valdivia Province
Valdivia Province (; ) is one of two Provinces of Chile, provinces of the southern Chilean Regions of Chile, region of Los Ríos Region, Los Ríos (XIV). The provincial capital is Valdivia (city), Valdivia. Located in the province are two importan ...
in mainland Chile) and ''Reithrodon longicaudatus'' (from a small island near Chiloé),[ both of which are now classified as ''Irenomys tarsalis''.][Kelt, 1993, p. 1] Philippi's ''Reithrodon longicaudatus'' was transferred into a new genus, ''Irenomys'', by Oldfield Thomas
Michael Rogers Oldfield Thomas (21 February 1858 – 16 June 1929) was a British zoologist.
Career
Thomas worked at the Natural History Museum, London, Natural History Museum on mammals, describing about 2,000 new species and subspecies for ...
in February 1919. The name, which means "peace mouse" in Greek, referred to the end of World War I four months before.[Thomas, 1919, p. 201] Another of the species Philippi described in 1900, ''Mus mochae'', was later transferred to ''Irenomys'' because of a mismatch between the skin and skull, but it is in fact a member of the genus ''Abrothrix
''Abrothrix'' is a genus of rodent in the tribe Abrotrichini of family Cricetidae.
It contains the following living species:Teta et al., 2017
*''Abrothrix andina''
*''Abrothrix hershkovitzi''
*''Abrothrix hirta''
*''Abrothrix illutea''
*''Abrothri ...
'' and not closely related to ''Irenomys''. In his 1943 work on ''The mammals of Chile'', Wilfred Hudson Osgood
Wilfred Hudson Osgood (December 8, 1875 – June 20, 1947) was an American zoologist.
Biography
Osgood was born in Rochester, New Hampshire, the oldest child of a family of watchmakers. The family moved to California in 1888 and he went to study ...
recognized the close relation between Philippi's ''Mus tarsalis'' and ''Reithrodon longicaudatus'' and referred them to a single species, then called ''Irenomys tarsalis''.[Osgood, 1943, p. 219] Osgood retained two 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 ...
, ''Irenomys tarsalis tarsalis'' on the mainland and ''Irenomys tarsalis longicaudatus'' on Chiloé and nearby islands, on the basis of slight differences in pelage coloration. In the few mature specimens of the latter subspecies that Osgood had, the underparts are somewhat lighter than in examples of ''I. t. tarsalis'', which has a pinkish color in the underparts, but Osgood stressed that further material could well indicate that the two forms could not be distinguished.[Osgood, 1943, p. 220]
In his description of the genus, Thomas opined that ''Irenomys'' is most closely related to ''Phyllotis
''Phyllotis'' is a genus of rodent in the family Cricetidae. These mice are commonly confused with ''Auliscomys, Graomys'' and ''Loxodontomys.'' ''.'' In order to tell these genera apart, one must look at the tail. Species in the genus ''Phyllo ...
''.[ The group of genera related to ''Phyllotis'' was later formalized as the tribe ]Phyllotini
The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species c ...
, and ''Irenomys'' was often included there, but also excluded from it by some authors. In 1995, a cladistic
Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
analysis of Phyllotini on the basis of morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
*Morphology (archaeology), study of the shapes or forms of artifacts
*Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
provided evidence in favor of placement of ''Irenomys'' in the group, with some support for a close relation to '' Andinomys''. From 1999 on, DNA sequence data cast doubt on this assignment, as studies using the mitochondrial
A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...
cytochrome ''b'' gene and the nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
*Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
* Nuclear space
*Nuclear ...
IRBP gene placed ''Irenomys'' in a variety of positions, all outside Phyllotini, with ''Scolomys
''Scolomys'' is a genus of rodent in the tribe Oryzomyini of the family Cricetidae. Some evidence suggests that it is related to ''Zygodontomys''. It is characterized, among other traits, by spiny fur. It contains two species, '' S. melanops'' an ...
'', '' Sigmodon'', ''Euneomys
''Euneomys'' is a genus of rodents in the family Cricetidae.
It contains the following species:
* Patagonian chinchilla mouse (''Euneomys chinchilloides'')
* Burrowing chinchilla mouse (''Euneomys fossor'')
* Biting chinchilla mouse (''Euneomys m ...
'', and various large clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
s of sigmodontines all as sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
s in some analyses. Accordingly, it is now classified outside Phyllotini and considered as Sigmodontinae ''incertae sedis
or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
''.
Description
''Irenomys'' is a large mouse with a long, hairy tail, large eyes, and long and soft fur.[ The upperparts are rufous with fine dark lines and the underparts are buff, with the exact color varying by subspecies. The densely haired ears are medium-sized and blackish in color. The feet, which are large and broad, are nearly white. The tail, which ends in a slight pencil, is dark brown, with a somewhat lighter area present on the ventral side in some individuals.][Osgood, 1943, p. 218] The total length is , averaging , the tail length is , averaging , the hindfoot length is , averaging , the ear length is , averaging , and weight is , averaging .[ The ]karyotype
A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...
includes 64 chromosome
A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...
s, with a fundamental number
A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...
(FN) of 98.
The skull resembles that of some ''Rhipidomys
''Rhipidomys'' is a genus of rodents in the family Cricetidae, The following 25 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 fertil ...
'' species. The interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups.
In oryzomyine rodents, for example, the width, form, and ...
is narrow and the incisive foramina
In the human mouth, the incisive foramen (also known as: "''anterior palatine foramen''", or "''nasopalatine foramen''") is the opening of the incisive canals on the hard palate immediately behind the incisor teeth. It gives passage to blood vesse ...
are long, extending between the first molars.[ The upper ]incisor
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
s are deeply grooved. The molars are strongly hypsodont
Hypsodont is a pattern of dentition characterized by with high crowns, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cows and horses; all animals that feed on gritty, fibrous material. The oppos ...
(high-crowned) and consist of transverse, diamond-shaped laminae (plates), separated by deep valleys, which are joined at the midline by narrow ridges, similar to those of the African elephant
African elephants are members of the genus ''Loxodonta'' comprising two living elephant species, the African bush elephant (''L. africana'') and the smaller African forest elephant (''L. cyclotis''). Both are social herbivores with grey skin. ...
.
Distribution and ecology
''Irenomys tarsalis'' is restricted to forested habitats in Chile and western Argentina. In the northern part of its range, its distribution falls into two segments, one in coastal Chile and one further east in Chile and in adjacent Argentina, both of which extend north to about 36°S. Further south, it also occurs in Chile and adjacent Argentina, and also on numerous Chilean islands, including Chiloé. The southernmost records are at about 46°S. No fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
s are known.[ It generally occurs in humid and densely forested habitats, often with ]bamboo
Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...
vegetations, but a specimen has been reported from riparian
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...
vegetation at a small stream near the southern limit of its distribution and it is also found in unforested steppe habitat with scattered ''Austrocedrus chilensis
''Austrocedrus'' is a genus of conifer belonging to the cypress family (Cupressaceae). It has only one species, ''Austrocedrus chilensis'', native to the Valdivian temperate rain forests and the adjacent drier steppe-forests of central-southern C ...
'' trees. It does not occur on high elevations. It was a common species during a population peak of small rodents evidently caused by the flowering of quila (''Chusquea quila'') bamboo.[
It is found in association with other rodents such as '']Abrothrix olivaceus
''Abrothrix olivacea'', also known as the olive grass mouse or olive akodont,Musser and Carleton, 2005, p. 1090 is a species of rodent in the genus ''Abrothrix'' of family Cricetidae. It is found from northern Chile into southern Chile and A ...
'', ''Abrothrix longipilis
''Abrothrix longipilis'', also known as the long-haired grass mouse or long-haired akodont,Musser and Carleton, 2005, p. 1089 is a species of rodent in the family Cricetidae. It is endemic to central Argentina and Chile. Until 2014 it was th ...
'', ''Oligoryzomys longicaudatus
''Oligoryzomys longicaudatus'', also known as the long-tailed colilargo or long-tailed pygmy rice rat, is a species of rodent in the genus ''Oligoryzomys'' of the family Cricetidae. It is found in the southern Andes of Chile and Argentina, with a ...
'', ''Geoxus valdivianus
''Geoxus valdivianus'', also known as the long-clawed mole mouse or Valdivian long-clawed akodont, is a species of rodent in the tribe Abrotrichini of family Cricetidae found in the Valdivian temperate rain forests and Magellanic subpolar forests ...
'', and ''Auliscomys pictus
''Auliscomys'' is a genus of rodent 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 over ...
'', as well as the marsupials '' Rhyncholestes raphanurus'' and ''Dromiciops gliroides
The monito del monte (''Dromiciops gliroides''), or colocolo opossum, is a diminutive species of marsupial native only to south-western South America (Argentina and Chile). It is the only extant species in the ancient order Microbiotheria, and t ...
''.[ Remains of ''Irenomys'' have been found in owl pellets of the ]great horned owl
The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air") or the hoot owl, is a large owl native to the Americas. It is an extreme ...
(''Bubo virginianus''),[ ]rufous-legged owl
The rufous-legged owl (''Strix rufipes'') is a medium-sized owl. It is found in Argentina and Chile.
Taxonomy and systematics
The rufous-legged owl has two subspecies, the nominate ''Strix rufipes rufipes'' and ''S. r. sanborni''. The latter ...
(''Strix rufipes''),[Martínez, 1993, p. 214] and barn owl
The barn owls, owls in the genus '' Tyto'', are the most widely distributed genus of owls in the world. They are medium-sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons. The ter ...
(''Tyto alba''); other potential predator
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
s include another owl, the Austral pygmy-owl (''Glaucidium nanum''), and the South American gray fox
The South American gray fox (''Lycalopex griseus''), also known as the Patagonian fox, the ''chilla'' or ''zorro gris'' (gray fox or gray zorro), is a South America, South American species of ''Lycalopex'' (the "false" or lesser foxes) in the Ca ...
(''Pseudalopex griseus''), Darwin's fox
Darwin's fox or Darwin's zorro (''Lycalopex fulvipes'') is an endangered canid from the genus '' Lycalopex''. It is also known as the ''zorro chilote'' or ''zorro de Darwin'' in Spanish and lives in Nahuelbuta National Park, the Cordillera de ...
(''Pseudalopex fulvipes'') and Kodkod
The kodkod (''Leopardus guigna''), also called güiña, is the smallest felid species native to the Americas. It lives primarily in central and southern Chile, as well as marginally in adjoining areas of Argentina. Since 2002, it has been listed ...
(''Leopardus guigna'').[Kelt, 1993, p. 3]
Natural history and behavior
''Irenomys'' lives mainly in trees, but has also been caught on the ground.[ It climbs by moving both forefeet and both hindfeet alternately. It is docile, but will not readily enter a trap.][ The breeding season is in the Southern Hemisphere spring, extending into late summer. Litter size is three to six.][Kelt, 1993, p. 2] The animal mostly eats seeds and fruits, but its diet also includes various other plant and fungal
A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the tradit ...
materials.[
]
Conservation status
''Irenomys'' is not currently threatened and it is classified as "least concern" by the International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
. It occurs in several protected areas, but destruction of its forest habitat may pose a threat to some populations.[
]
References
Literature cited
*D'Elía, G., Luna, L., González, E.M. and Patterson, B.D. 2006. On the sigmodontine radiation (Rodentia, Cricetidae): An appraisal of the phylogenetic position of ''Rhagomys''. Molecular Phylogenetics and Evolution 38:558–564
*D'Elía, G., González, E.M. and Pardiñas, U.F.J. 2003. Phylogenetic analysis of sigmodontine rodents (Muroidea), with special reference to the akodont genus ''Deltamys''. Mammalian Biology 68:351–364.
*D'Elía, G. 2003. Phylogenetics of Sigmodontinae (Rodentia, Muroidea, Cricetidae), with special reference to the akodont group, and with additional comments on historical biogeography. Cladistics 19:307–323.
*Hershkovitz, P. 1962. Evolution of Neotropical cricetine rodents (Muridae) with special reference to the phyllotine group. Fieldiana Zoology 46:1–524.
*Kelt, D.A. 1993
Irenomys tarsalis
Mammalian Species 447:1–3.
*Kelt, D.A., Engilis, A. Jr., Torres, I.E. and Hitch, A.T. 2006. Ecologically significant range extension for the Chilean tree mouse, ''Irenomys tarsalis''. Mastozoología Neotropical 15(1):125–128.
*Martínez, D.R. 1993
Food habits of the rufous-legged owl (''Strix rufipes'') in temperate rainforests of southern Chile
Journal of Raptor Research 27(4):214–216.
*Musser, G.G. and Carleton, M.D. 2005. Superfamily Muroidea. Pp. 894–1531 in Wilson, D.E. and Reeder, D.M. (eds.)
Mammal Species of the World: a taxonomic and geographic reference. 3rd ed
Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp.
*Ojeda, A.A., Ríos, C.A. and Gallardo, M.H. 2004. Chromosomal characterization of ''Irenomys tarsalis'' (Rodentia, Cricetidae, Sigmodontinae). Mastozoología Neotropical 11(1):95–98.
*Osgood, W.H. 1943
The mammals of Chile
Fieldiana Zoology 30:1–268.
*Pardinas, U., Patterson, B., D'Elia, G. and Teta, P. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2.
www.iucnredlist.org
. Downloaded on November 6, 2009.
*Smith, M.F. and Patton, J.L. 1999. Phylogenetic relationships and the radiation of sigmodontine rodents in South America: Evidence from cytochrome ''b''. Journal of Mammalian Evolution 6(2):89–128.
*Steppan, S.J. 1995. Revision of the tribe Phyllotini (Rodentia: Sigmodontinae), with a phylogenetic hypothesis for the Sigmodontinae. Fieldiana Zoology 80:1–112.
*Thomas, O. 1919
On small mammals collected by Sr. E. Budin in North-western Patagonia
Annals and Magazine of Natural History (9)3:199–212.
{{Taxonbar, from=Q301642
Mammals of Argentina
Mammals of Chile
Phyllotini
Mammals described in 1900
Taxa named by Oldfield Thomas
Taxonomy articles created by Polbot
Fauna of the Valdivian temperate forests