''Transandinomys'' is a

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 ...

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 ...

s in the tribe

Oryzomyini Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera,Weksler et al., 2006, table 1 distributed from the eastern United States to the southernmost parts of S ...

of 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 870 species, it is either the largest or second-largest family ...

. It includes two species—'' T. bolivaris'' and '' T. talamancae''—found in forests from

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. It is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Ocean at the Gulf of Fonseca, ...

in Central America south and east to southwestern

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

and northwestern

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

in northern South America. Until 2006, its members were included in the genus ''

Oryzomys ''Oryzomys'' is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (''O. palustris'') of the United States and ...

'', but

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis showed that they are not closely related to the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of that genus, and they have therefore been placed in a new genus. They may be most closely related to genera like ''

Hylaeamys ''Hylaeamys'' is a genus of South American oryzomyine rodents found principally in humid forested areas east of the Andes. The species in this genus have historically been placed in ''Oryzomys''. They are most closely related to '' Euryoryzomys' ...

'' and ''

Euryoryzomys ''Euryoryzomys'' is a genus of rodents in the tribe Oryzomyini of family Cricetidae. It includes seven species, which are distributed in South America. Until 2006, its members were included in the genus ''Oryzomys'', but they are not closely relat ...

'', which contain very similar species. Both species of ''Transandinomys'' have had eventful

taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

histories. ''Transandinomys bolivaris'' and ''T. talamancae'' are medium-sized, soft-furred rice rats. The upperparts—brownish in ''T. bolivaris'' and reddish in ''T. talamancae''—are much darker than the whitish underparts. Both species are characterized by very long

vibrissae Whiskers, also known as vibrissae (; vibrissa; ) are a type of stiff, functional hair used by most therian mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarser as t ...

(whiskers); those of ''T. bolivaris'' are particularly long. In addition to whisker length and fur color, several other morphological differences distinguish the two, including the wider first upper molar in ''T. bolivaris''. Species of ''Hylaeamys'' and ''Euryoryzomys'' also differ from ''Transandinomys'' in some details of the skull and teeth and have shorter whiskers. Species of ''Transandinomys'' live on the ground, are active during the night, eat both plant and animal matter, and construct nests of vegetation. Both are

hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

to various external

parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

. They are in no apparent danger of extinction and have been assessed as "

Least Concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

" in 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 ...

Taxonomy

The first species of ''Transandinomys'' (from Neo-Latin ''transandinus'': "transandean", ''i.e.'', "crossing or beyond the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

" ( adj.) and Greek ''mys'': "mouse, rat") to be scientifically described was '' T. talamancae'', named as ''Oryzomys talamancae'' by Joel A Allen in 1891. Several other species were soon added to the genus ''

'', then more broadly defined than currently, that are now classified in ''Transandinomys'',Weksler et al., 2006, p. 25 including ''Oryzomys bolivaris'' (now '' Transandinomys bolivaris'') by Allen in 1901. In his 1918 review of North American ''Oryzomys'',

Edward Alphonso Goldman Edward Alphonso Goldman (July 7, 1873 – September 2, 1946) was an American field naturalist and mammalogist. He worked extensively in Mexico with Edward William Nelson and described and revised many groups of mammals. He was considered a leading ...

placed ''Oryzomys talamancae'' and ''Oryzomys bombycinus'' (=''T. bolivaris'') each in their own group, but thought them closely related.Goldman, 1918, p. 73 In 1960, ''O. talamancae'' was synonymized with "''Oryzomys capito''" (=''

Hylaeamys megacephalus ''Hylaeamys megacephalus'', also known as Azara's broad-headed oryzomys or the large-headed rice rat, is a species of rodent in the genus ''Hylaeamys'' of family Cricetidae, of which it is the type species. It is found mainly in lowland tropical ...

''), but it has again been recognized as a separate species since 1983. The species was reviewed by

Guy Musser Guy Graham Musser (August 10, 1936 – October 2019) was an American zoologist. His main research was in the field of the rodent subfamily Murinae, in which he has described many new species. Musser was born in Salt Lake City, Utah. He attended ...

and Marina Williams in 1985 and again by Musser and colleagues in 1998, who documented the diagnostic characters of the species, its synonyms, and its distribution.Musser and Carleton, 2005, p. 1155 The 1998 study by Musser and colleagues also documented ''Oryzomys bolivaris'' as the correct name for the species previously known as ''Oryzomys bombycinus'' and reviewed that species.Musser and Carleton, 2005, p. 1146 In 2006, Marcelo Weksler published a broad

analysis of

, the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

to which ''Oryzomys'' and related genera belong, using morphological data and

DNA sequence A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the nu ...

s from the IRBP gene. ''O. talamancae'' appeared within " clade B", together with other species formerly associated with ''Oryzomys capito''. Some analyses placed it closest to species now placed in ''

'' or ''

Nephelomys ''Nephelomys'' is a genus of South American oryzomyine rodents found in the Andes from Bolivia to Venezuela, with a westward extension into the mountains of Costa Rica. Its generic name is derived from the Ancient Greek word ''nephelê'' "mist", ...

'', but with low support. ''O. bolivaris'' was not included. Species of ''Oryzomys'' included in Weksler's study did not cluster together in his results, but instead appeared dispersed across Oryzomyini, indicating that the genus was

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

and should be split up. Later in the same year, Weksler, Alexandre Percequillo, and Robert Voss introduced ten new genera of Oryzomyini formerly placed in ''Oryzomys'', including ''Transandinomys'' for ''Oryzomys talamancae'' and ''O. bolivaris'', with the former as the

. ''Transandinomys'' is now one of about thirty genera within Oryzomyini, a diverse group of well over a hundred species. Oryzomyini is one of several tribes within 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 ...

of the family

, which includes hundreds of other species of mainly small rodents, distributed chiefly in Eurasia and the Americas.

Description

''Transandinomys'' species are medium-sized, soft-furred rice rats.Tirira, 2007, p. 198 They closely resemble other medium-sized lowland forest rice-rats, such as ''

'' and ''

'' from the

Amazon rainforest The Amazon rainforest, also called the Amazon jungle or Amazonia, is a Tropical and subtropical moist broadleaf forests, moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin ...

and surrounding areas and ''

Handleyomys alfaroi ''Handleyomys alfaroi'', also known as Alfaro's rice rat or Alfaro's oryzomys, is a species of rodent in the genus ''Handleyomys'' of family Cricetidae. It is found in Belize, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexi ...

'' from Central America and northwestern South America. In general, ''Transandinomys'' are distinguished from those animals by their very long superciliary vibrissae (

whiskers Whiskers, also known as vibrissae (; vibrissa; ) are a type of stiff, functional hair used by most therian mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarser as ta ...

above the eyes). ''Euryoryzomys'' species are in general slightly largerMusser et al., 1998, p. 13 and ''Hylaeamys'' are as large as ''Transandinomys'', so that the only feature of external

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, ...

that distinguishes the two genera is the length of the vibrissae.Weksler et al., 2006, p. 15 ''Handleyomys alfaroi'' is smaller than both species of ''Transandinomys'', but juvenile ''Transandinomys'' may be confused with similarly colored adult ''H. alfaroi''. The fur is brownish (''T. bolivaris'') or reddish (''T. talamancae'') above and lighter below, appearing whitish, but the hairs on the underparts have gray bases. The

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the n ...

is large. The mystacial (above the mouth) and superciliary vibrissae both extend to at least the back margin of the ears when laid back against the head, but are much longer in ''T. bolivaris''. The pinna (external ear) is large. On the hindfeet, which are long and narrow, ungual tufts of hairs surround the bases of the toes. In ''T. bolivaris'', the sole usually entirely lacks squamae (small, scale-like structures), but ''T. talamancae'' does have squamae on part of its sole. The claw of the first toe extends about to the middle of the first

phalange The phalanges (: phalanx ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. Structure ...

of the second and that of the fifth toe extends nearly to the base of the second phalange of the fourth. The tail is at least about as long as the head and body, sometimes slightly longer. The tail is darker above than below in ''T. talamancae'', but there may not be a difference in color in ''T. bolivaris''. The tail appears naked, but is covered with fine hairs. Females have four pairs of

mammae A mammary gland is an exocrine gland that produces milk in humans and other mammals. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, humans ...

, as usual in oryzomyines. Like most rice rats, ''Transandinomys'' species have twelve

thoracic The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main ...

(chest) and seven

lumbar In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm (anatomy), diaphragm and the sacrum. Naming and location The lumbar region is sometimes referred to as the lowe ...

vertebrae. According to a study in Costa Rica, ''T. bolivaris'' has 58

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 and the number of chromosomal arms (

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 ...

) is 80 (2n = 58, FN = 80).Musser et al., 1998, p. 125 Studies in Ecuador and Venezuela have recorded several different

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 ...

s in ''T. talamancae'', with the number of chromosomes ranging from 34 to 54 and the fundamental number from 60 to 67.Musser et al., 1998, table 13

Skull and teeth

In the skull, the rostrum (front part) is long. The

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

s are short, with their back margin not extending beyond the

lacrimal bone The lacrimal bones are two small and fragile bones of the facial skeleton; they are roughly the size of the little fingernail and situated at the front part of the medial wall of the orbit. They each have two surfaces and four borders. Several bon ...

s, which are in contact with both the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

ry and

frontal bone In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...

s. The

zygomatic notch In rodent anatomy, the zygomatic plate is a bony plate derived from the flattened front part of the zygomatic arch (cheekbone). At the back, it connects to the front (maxillary) root of the zygomatic arch, and at the top it is connected to the ...

is moderately developed and the

jugal bone The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic bone, zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by spe ...

is small, so that when seen from the side the maxillary and

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestra ...

parts of the

zygomatic arch In anatomy, the zygomatic arch (colloquially known as the cheek bone), is a part of the skull formed by the zygomatic process of temporal bone, zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the ...

(cheekbone) overlap. Usually, the suture (line of fusion) between the frontal and the squamosal is continuous with that between the frontal and the

parietal bone The parietal bones ( ) are two bones in the skull which, when joined at a fibrous joint known as a cranial suture, form the sides and roof of the neurocranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four bord ...

. In ''T. talamancae'', the parietals usually extend from the roof of the braincase broadly on to the sides, but in ''T. bolivaris'' they are more commonly restricted to the roof. 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 ...

(openings in the front part of the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

) are short, not extending between the first

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

. The posterolateral palatal pits (small openings at the back of the palate, near the third molars) are poorly developed. The mesopterygoid fossa, the gap behind the back margin of the palate, does not usually reach forward between the maxillaries. Its roof either is wholly ossified or contains small

sphenopalatine vacuities In rodents, sphenopalatine vacuities are perforations of the roof of the mesopterygoid fossa, the open space behind the palate, in between the parapterygoid fossae. They may perforate the presphenoid or basisphenoid bone. Their development and ...

. Unlike in some other oryzomyines, the buccinator-masticatory foramen and the

foramen ovale accessorium In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arteries ...

, two

foramina In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arter ...

(openings) in the skull, are not separated by an

alisphenoid strut In some rodents, the alisphenoid strut is an extension of the alisphenoid bone that separates two foramina in the skull, the masticatory–buccinator foramen and the foramen ovale accessorium. The presence or absence of this strut is variable be ...

. The pattern of grooves and foramina in the skull indicates that the circulation of the arteries of the head follows the primitive pattern, as in most similar species but unlike in ''

''. Usually, the mastoid bone contains small openings (fenestrations) in ''T. talamancae'', but not in ''T. bolivaris''. In the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

(lower jaw), the capsular process (a

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...

at the root of the

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 ...

) is weak to absent and the upper and lower masseteric ridges, which anchor some of the chewing muscles, do not join into a single crest and reach their front margin below the first molar. The upper incisor is opisthodont, with the cutting edge oriented backward. As usual in oryzomyines, the molars are

brachydont The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...

(low-crowned). The first upper molar is narrower in ''T. talamancae'' than in ''T. bolivaris''. Unlike in many other rice rats, including ''Handleyomys alfaroi'' and ''

'' species, the

mesoflexus Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...

on the second upper molar, which separates the paracone (one of the main cusps) from the mesoloph (an accessory crest), is not divided in two by an enamel bridge. On the upper third molar, the hypoflexus (which in oryzomyines ranges from a slight indentation on the lingual, or inner, side of the tooth to a conspicuous valley between the main cusps) is more developed in ''Euryoryzomys'' than in ''Transandinomys''.Weksler et al., 2006, p. 14 The

hypoflexid Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...

on the second lower molar, the main valley between the cusps, extends more than halfway across the crown; it is much shorter in ''H. alfaroi'', ''Euryoryzomys'', and ''

Hylaeamys yunganus ''Hylaeamys yunganus'', also known as the Amazonian oryzomys or Yungas rice rat, is a species of rodent in the genus ''Hylaeamys'' of family Cricetidae. It is found in lowland tropical rainforest throughout Amazonia, in northeastern Bolivia, east ...

''. Each of the upper molars has three roots (two at the labial, or outer, side and one at the lingual, or inner, side) and each of the lowers has two (one at the front and one at the back); both species of ''Transandinomys'' lack the additional small roots that are present in various other oryzomyines, including species of ''Euryoryzomys'', ''Nephelomys'', and ''Handleyomys''.

Distribution, ecology, and behavior

The distribution of ''Transandinomys'' extends from eastern Honduras through Nicaragua, Costa Rica, Panama, and Colombia south and east to southwestern Ecuador and northern Venezuela, generally west and north of the Andes. The ranges of the two species overlap but are distinct. ''T. bolivaris'' occurs from Honduras mainly on the Caribbean side of Central America south to western Colombia and northwestern Ecuador, up to 1800 m (5900 ft) above sea level.Musser et al., 1998, p. 113 ''T. talamancae'', which is found up to 1525 m (5000 ft) above sea level, is less widely distributed in Central America, as it is not known further north than northwestern Costa Rica, but is more widely distributed in South America, occurring into far southwestern Ecuador and northern Venezuela. It has also been recorded south of the Venezuelan Andes, in the narrow strip of forest between the

Llanos The Llanos ( Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, ...

and the mountains. Both species are forest rats, but whereas ''T. bolivaris'' is restricted to humid forest formations, ''T. talamancae'' apparently is more tolerant of drier forest, which explains its wider South American distribution. Both species live on the ground, are active during the night, are solitary, and feed mainly on fruits and seeds, but may also eat herbs and insects. They build nests of leaves and branches among vegetation, for example in a tree hollow, or under rocks. In Panama, ''T. talamancae'' breeds throughout the year and the average litter size is about six. Various species of mites,

chigger ''Trombicula'', known as chiggers, red bugs, scrub-itch mites, or berry bugs, are small arachnids (eight-legged arthropods) in the Trombiculidae family. In their larval stage, they attach to various animals and humans, then feed on skin, often ...

s, fleas, and sucking lice have been recorded as parasites on both species.

Conservation status

''Transandinomys talamancae'' is common or even abundant, but ''T. bolivaris'' generally occurs less frequently. Because both species are widespread, presumably have large populations, and occur in numerous

protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewood ...

s, they are assessed as "

" by the

;

deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

is noted as a possible threat to ''T. bolivaris'', but ''T. talamancae'' is said to lack major threats.Anderson et al., 2008; Gómez-Laverde et al., 2008

Notes

References

Literature cited

* Allen, J.A. 1891
Descriptions of two supposed new species of mice from Costa Rica and Mexico, with remarks on ''Hesperomys melanophrys'' of Coues
''Proceedings of the United States National Museum'' 14(850):193–196. * Allen, J.A. 1901
New South American Muridae and a new ''Metachirus''
''Bulletin of the American Museum of Natural History'' 14:405–412. * Anderson, R.P., Aguilera, M., Gómez-Laverde, M., Samudio, R. and Pino, J. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2.
www.iucnredlist.org
. Downloaded on June 26, 2010. * Brennan, J.M. and Yunker, C.E. 1966
The chiggers of Panama (Acarina: Trombiculidae)
Pp. 221–266 in Wenzel, R.L. and Tipton, V.J. (eds.). Ectoparasites of Panama. Chicago: Field Museum of Natural History. * Fleming, T.H. 1971
Population ecology of three species of Neotropical rodents
''Miscellaneous Publications of the Museum of Zoology, University of Michigan'' 143:1–77. * Goldman, E.A. 1918
The rice rats of North America
''North American Fauna'' 43:1–100. * Gómez-Laverde, M., Rivas, B., Timm, R. and Pino, J. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2.
www.iucnredlist.org
. Downloaded on June 26, 2010. * 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. * Musser, G.G., Carleton, M.D., Brothers, E.M. and Gardner, A.L. 1998
Systematic studies of oryzomyine rodents (Muridae: Sigmodontinae): diagnoses and distributions of species formerly assigned to ''Oryzomys "capito"''
''Bulletin of the American Museum of Natural History'' 236:1–376. * Reid, F. 2009. ''A Field Guide to the Mammals of Central America and Southeast Mexico. 2nd edition''. Oxford University Press US, 346 pp. * Steppan, S.J. 1995
Revision of the tribe Phyllotini (Rodentia: Sigmodontinae), with a phylogenetic hypothesis for the Sigmodontinae
''Fieldiana Zoology'' 80:1–112. * Tipton, V.J. and Méndez, E. 1966
The fleas (Siphonaptera) of Panama
Pp. 289–385 in Wenzel, R.L. and Tipton, V.J. (eds.). ''Ectoparasites of Panama''. Chicago: Field Museum of Natural History. * Tipton, V.J., Altman, R.M. and Keenan, C.M. 1966
Mites of the subfamily Laelaptinae in Panama (Acarina: Laelaptidae)
Pp. 23–82 in Wenzel, R.L. and Tipton, V.J. (eds.). ''Ectoparasites of Panama''. Chicago: Field Museum of Natural History. * Tirira, D. 2007. ''Guia de campo de los mamíferos del Ecuador''. Quito: Ediciones Murciélago Blanco, publicación especial sobre los mamíferos del Ecuador 6, 576 pp. (in Spanish). * Weksler, M. 2006
Phylogenetic relationships of oryzomyine rodents (Muroidea: Sigmodontinae): separate and combined analyses of morphological and molecular data
''Bulletin of the American Museum of Natural History'' 296:1–149. * Weksler, M., Percequillo, A.R. and Voss, R.S. 2006
Ten new genera of oryzomyine rodents (Cricetidae: Sigmodontinae)
''American Museum Novitates'' 3537:1–29.

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* * {{Featured article Rodent genera Taxa named by Marcelo Weksler Taxa named by Alexandre Reis Percequillo