Luzon Montane Forest Mouse
Encyclopedia
The Luzon Montane Forest Mouse (Apomys datae) is a species
of rodent
in the family
Muridae
, from the genus
Apomys
.
It occurs only in the Philippines
, where it has been found on the large northern island Luzon
(in the Cordillera Central and on the coast of Ilocos Norte
). It is most closely related to the Large Mindoro Forest Mouse
, which occurs on Mindoro
. There may be another related species in the Sierra Madre
, but this species is undescribed as of yet. The Luzon Montane Forest Mouse is a relatively large, ground-dwelling rat with a tail that is quite short for its genus.
, Rhynchomys
and Crunomys
. During this expedition, in February, England
explorer John Whitehead
captured a number of unknown rats on a site called Lepanto on Mount Data, at an altitude of approximately 2500 m (8,202.1 ft). In 1898, British biologist Oldfield Thomas
described these animals as an "interesting species", but identified them as Mus chrysocomus, a species from Sulawesi
that is now known as Yellow-haired Hill Rat
(Bunomys chrysocomus) and reckoned among the genus Bunomys
, which is not actually closely related to Apomys. Thomas sent a specimen to the Staatliches Museum für Tierkunde
in Dresden
, where it was concluded by Adolf Bernard Meyer
that the animal did not resemble Mus chrysocomus. Meyer described th animal as Mus datae in 1899, after its type locality - Mount Data (at the time the generic name Mus
was used more broadly than it is now). For a long time, little was known about Mus datae, until 1913, when American
biologist Ned Hollister
described eight rats from Luzon under the name Epimys datae ("Epimys" was the name of the genus that would later become Rat
tus). These were in fact examples of the Himalayan Field Rat
(Rattus nitidus), but they were only identified as such in 1977, by Guy Musser
, another American biologist. Meanwhile, in Britain, John Ellerman had finally placed Mus datae with its relatives in Apomys, in 1941. Eleven years later, in 1952, American zoologist
Colin Campbell Sanborn announced that he had captured 54 specimens of A. datae on Mount Data. A good part of this catch, however, was later found to consist of specimens of the Luzon Cordillera Forest Mouse
(A. abrae), a species which had been described by Sanborn in the same article in which he had made his announcement.
In a 1982 article, Musser defined the genus Apomys and gave the first modern description of A. datae, while also correcting Sanborn's mistake in the identification of his collection. It was revealed that Sanborn had not been the only one to get the major species of Apomys from Luzon cofused: the holotype
of the species Apomys Major, described by Gerrit Smith Miller
of the Smithsonian Institution
in 1910, turned out to have been a specimen of A. datae, while the other animals to have been identified as A. major were discovered to be examples of A. abrae. Since that time, Apomys major has been considered a subjective synonym
of A. datae. Musser identified A. datae as the only member of the "Apomys datae group" within the genus, being different from all other species. In 1993 and 1994, the species was observed in the Sierra Madre, at an altitude between 760 and 1650 m (2,493.4 and 5,413.4 ft), but this probably concerns a population of a separate, undescribed species. A second species within the A. datae group was described by Luis Ruedas, in 1995: Apomys gracilirostris
. In the 21st century, the knowledge about A. datae was expanded with data from genetic
research. In 2002, the karyotype
was revealed, and in 2003, the phylogenetic
relationship with A. gracilirostris was confirmed, based on common features in the species' DNA
. Most recently, the animal has been found on several new locations in North Luzon.
that occurs exclusively on the Philippines, and in addition to Apomys, also includes Rhynchomys, Chrotomys
and Archboldomys
. Animals in this division share several morphological and genetic features. Within this group, Apomys is by far the biggest and most extensive genus, containing small, inconspicuous wood mice which are common to the whole of the Philippines, while the other, more specialized genera are barely ever found outside Luzon. Apomys itself was divided into two groups, in the aforementioned article by Musser from 1982: the datae group, containing only A. datae, and the abrae-hylocetes group, containing all other species. Animals in these two groups differ in the way in which the head is supplied with blood
from arteries
. Since the publication of Musser's article, another species has been described that falls into the datae group: A. gracilirostris. This relationship is further supported by other similarities: both species are relatively large for the genus and have a relatively long snout.
In 2003, a phylogenetic study was published which compared DNA sequences from the cytochrome b
gene of thirteen species of Apomys. This study confirmed the proposed relationship between the Large Mindoro Forest Mouse (A. gracilirostris) and the Luzon Montane Forest Mouse (A. datae), as well as the status of the datae group as a sister group of the other species of Apomys.
The phylogenetic relationships of the Luzon Montane Forest Mouse can be summarized as follows.
According to this study, the split between the Luzon Montane Forest Mouse and the Large Mindoro Forest Mouse took place some three million years ago, as calculated using a molecular clock
, putting it in the pliocene
. It was also estimated that Apomys dates back more than four million years, with the Chromotys division being again more ancient by another two million years. Another, more elaborate study concluded that the Chromotys division was older still, at more than ten million years, and that the split between the Chromotys division and its closest relatives, a predominantly Africa
n group including Mus, Otomys
and Mastomys
, took place some sixteen million years ago. Seeing as Apomys probably originated on Luzon, The Luzon Montane Forest Mouse likely developed directly from the ancestor species of the datae group, while the Large Mindoro Forest Mouse is the result of a pliocene migration to Mindoro.
mammary glands, and a large number of skull
characteristics.
The Luzon Montane Forest Mouse is a large, thickset species with a tail that is about the same length as the body. The soft, thick dorsal fur is dark brown, while the ventral side of the body is a cream white. The hind feet are partly brown in colour on the dorsal side, but otherwise white. The tail is brown on the dorsal side, and a cream white ventrally. The animal has a large skull with a square-shaped neurocranium. Some of its skull characteristics are so special that they set the animal apart from most every other species of Apomys. One specimen has a head-torso-length of 143 mm, a tail length of 144 mm and a hind feet length of 34 mm. The specimens captured by Sanborn on Mount Data have a mean
skull length of 39.2 mm (37.0 to 40.6 mm with a standard deviation
of 1.1 mm). The Luzon Montane Forest Mouse's holotype has a skull length of 39.9 mm; that of A. major has a length of 38.4 mm.
The animal has a karyotype of 2n=44 and FN=54, which consists of five pairs of four-armed chromosomes and sixteen pairs of two-armed (telocentric) chromosomes. The X-chromosome is a large, and the Y-chromosome a small telocentric chromosome. This karyotype has much in common with that of the Least Forest Mouse
(Apomys musculus), while at the same time being very different from the karyotypes of species form other parts of the Philippines (the karyotype of the Large Mindoro Forest Mouse, on a side note, is unknown).
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Muridae
Muridae
Muridae is the largest family of mammals. It contains over 600 species found naturally throughout Eurasia, Africa, and Australia. They have been introduced worldwide. The group includes true mice and rats, gerbils, and relatives....
, from the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Apomys
Apomys
Apomys is a genus of rodent endemic to the Philippines. Mice belonging to this genus are generally called Philippine forest mice and can be found on most islands of the Philippines except in Palawan, the Sulu Archipelago, and the Batanes and Babuyan group of islands.Apomys mice weigh from 18g to...
.
It occurs only in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, where it has been found on the large northern island Luzon
Luzon
Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon...
(in the Cordillera Central and on the coast of Ilocos Norte
Ilocos Norte
Ilocos Norte is a province of the Philippines located in the Ilocos Region in Luzon. Its capital is Laoag City and is located at the northwest corner of Luzon Island, bordering Cagayan and Apayao to the east, and Abra and Ilocos Sur to the south...
). It is most closely related to the Large Mindoro Forest Mouse
Large Mindoro Forest Mouse
The Large Mindoro Forest Mouse is a species of rodent in the family Muridae, from the genus Apomys. It is found only in the Philippines. Its natural habitat is subtropical or tropical moist montanes. The Large Mindoro Forest Mouse is a large mouse with large feet, a long tail and an elongated...
, which occurs on Mindoro
Mindoro
Mindoro is the seventh-largest island in the Philippines. It is located off the coast of Luzon, and northeast of Palawan. The southern coast of Mindoro forms the northeastern extremum of the Sulu Sea.-History:...
. There may be another related species in the Sierra Madre
Sierra Madre (Philippines)
The Sierra Madre is a mountain range in The Philippines. It is located along the north-eastern coast of Luzon Island, running north/south. Quezon National Forest Park is situated in the range.-Geography:...
, but this species is undescribed as of yet. The Luzon Montane Forest Mouse is a relatively large, ground-dwelling rat with a tail that is quite short for its genus.
Discovery
The Luzon Montane Forest Mouse was the first species of Apomys ever to be discovered. In 1895, an expedition was organised which brought to Europe the first specimens of several genera, including CarpomysCarpomys
Carpomys is a genus of rodent in the family Muridae.It contains the following species:* Short-footed Luzon Tree Rat * White-bellied Luzon Tree Rat...
, Rhynchomys
Shrewlike rat
The shrewlike rats, genus Rhynchomys, also known as the tweezer-beaked rats are a group of unusual Old World rats found only on the island of Luzon in the Philippines. They look a great deal like shrews and are an example of convergent evolution...
and Crunomys
Crunomys
Crunomys is a genus of rodent in the family Muridae.It contains the following species:* Celebes Shrew Rat * Northern Luzon Shrew Rat * Mindanao Shrew Rat...
. During this expedition, in February, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
explorer John Whitehead
John Whitehead (explorer)
John Whitehead was an English explorer, naturalist and professional collector of bird specimens.Whitehead travelled in Malacca, North Borneo, Java, and Palawan between 1885 and 1888, where he collected a number of zoological specimens new to science, including Whitehead's Broadbill , writing up...
captured a number of unknown rats on a site called Lepanto on Mount Data, at an altitude of approximately 2500 m (8,202.1 ft). In 1898, British biologist Oldfield Thomas
Oldfield Thomas
Oldfield Thomas FRS was a British zoologist.Thomas worked at the Natural History Museum on mammals, describing about 2,000 new species and sub-species for the first time. He was appointed to the Museum Secretary's office in 1876, transferring to the Zoological Department in 1878...
described these animals as an "interesting species", but identified them as Mus chrysocomus, a species from Sulawesi
Sulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
that is now known as Yellow-haired Hill Rat
Yellow-Haired Hill Rat
The Yellow-haired Hill Rat is a species of rodent in the family Muridae.It is found only in Indonesia.-References:* Baillie, J. 1996. . Downloaded on 19 July 2007....
(Bunomys chrysocomus) and reckoned among the genus Bunomys
Bunomys
Bunomys is a genus of rodent from Sulawesi and Butung Island.-Species:Genus Bunomys*Andrew's Hill Rat, Bunomys andrewsi J. A...
, which is not actually closely related to Apomys. Thomas sent a specimen to the Staatliches Museum für Tierkunde
Staatliches Museum für Tierkunde Dresden
The State Museum of Zoology in Dresden is a natural history museum that houses 10,000-50,000 specimens, including skeletons and large insect collections. Many are types. The collection suffered war damage and whilst catalogued the database is not computerized. Loans are possible and material can...
in Dresden
Dresden
Dresden is the capital city of the Free State of Saxony in Germany. It is situated in a valley on the River Elbe, near the Czech border. The Dresden conurbation is part of the Saxon Triangle metropolitan area....
, where it was concluded by Adolf Bernard Meyer
Adolf Bernard Meyer
Adolf Bernard Meyer was a German anthropologist, ornithologist and entomologist.-Biography:...
that the animal did not resemble Mus chrysocomus. Meyer described th animal as Mus datae in 1899, after its type locality - Mount Data (at the time the generic name Mus
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
was used more broadly than it is now). For a long time, little was known about Mus datae, until 1913, when American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
biologist Ned Hollister
Ned Hollister
Ned Hollister was an American biologist primarily known for studying mammals. From 1916 until his death he was Superintendent of the National Zoological Park...
described eight rats from Luzon under the name Epimys datae ("Epimys" was the name of the genus that would later become Rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
tus). These were in fact examples of the Himalayan Field Rat
Himalayan Field Rat
The Himalayan Field Rat is a species of rodent in the family Muridae.It is found in Bangladesh, China, India, Indonesia, Laos, Myanmar, Nepal, Sumatra, Palau, the Philippines, Thailand, and Vietnam.-References:...
(Rattus nitidus), but they were only identified as such in 1977, by Guy Musser
Guy Musser
Guy Graham Musser is an American zoologist. His main research field is the subfamily Murinae, in which he has described many new species.Musser was born in Salt Lake City, Utah...
, another American biologist. Meanwhile, in Britain, John Ellerman had finally placed Mus datae with its relatives in Apomys, in 1941. Eleven years later, in 1952, American zoologist
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...
Colin Campbell Sanborn announced that he had captured 54 specimens of A. datae on Mount Data. A good part of this catch, however, was later found to consist of specimens of the Luzon Cordillera Forest Mouse
Luzon Cordillera Forest Mouse
The Luzon Cordillera Forest Mouse is a species of rodent in the family Muridae.It is found only in the Philippines.-References:* Rodent Specialist Group 1996. . Downloaded on 19 July 2007....
(A. abrae), a species which had been described by Sanborn in the same article in which he had made his announcement.
In a 1982 article, Musser defined the genus Apomys and gave the first modern description of A. datae, while also correcting Sanborn's mistake in the identification of his collection. It was revealed that Sanborn had not been the only one to get the major species of Apomys from Luzon cofused: the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of the species Apomys Major, described by Gerrit Smith Miller
Gerrit Smith Miller
Gerrit Smith Miller, Jr. was an American zoologist.He was born in Peterboro, New York in 1869. He graduated from Harvard University in 1894 and worked under Clinton Hart Merriam at the United States Department of Agriculture...
of the Smithsonian Institution
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...
in 1910, turned out to have been a specimen of A. datae, while the other animals to have been identified as A. major were discovered to be examples of A. abrae. Since that time, Apomys major has been considered a subjective synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
of A. datae. Musser identified A. datae as the only member of the "Apomys datae group" within the genus, being different from all other species. In 1993 and 1994, the species was observed in the Sierra Madre, at an altitude between 760 and 1650 m (2,493.4 and 5,413.4 ft), but this probably concerns a population of a separate, undescribed species. A second species within the A. datae group was described by Luis Ruedas, in 1995: Apomys gracilirostris
Large Mindoro Forest Mouse
The Large Mindoro Forest Mouse is a species of rodent in the family Muridae, from the genus Apomys. It is found only in the Philippines. Its natural habitat is subtropical or tropical moist montanes. The Large Mindoro Forest Mouse is a large mouse with large feet, a long tail and an elongated...
. In the 21st century, the knowledge about A. datae was expanded with data from genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
research. In 2002, the karyotype
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
was revealed, and in 2003, the phylogenetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
relationship with A. gracilirostris was confirmed, based on common features in the species' DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
. Most recently, the animal has been found on several new locations in North Luzon.
Evolution and phylogenetic relationships
The Luzon Montane Forest Mouse belongs to the Chrotomys division, a group within the MurinaeMurinae
The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. This subfamily is larger than all mammal families except the Cricetidae and Muridae, and is larger than all mammal orders except the bats and the remainder of the...
that occurs exclusively on the Philippines, and in addition to Apomys, also includes Rhynchomys, Chrotomys
Chrotomys
The genus Chrotomys contain a unique group of rodents found only in the Philippines, specifically the islands of Luzon, Mindoro, and Sibuyan. Instead of being predominantly herbivorous or omnivorous like other murines, these rats feed predominantly on invertebrates although they do eat some...
and Archboldomys
Archboldomys
Archboldomys, the shrew-mice, are a genus of rodents in the family Muridae. They are carnivores that feed on invertebrates much like shrews do...
. Animals in this division share several morphological and genetic features. Within this group, Apomys is by far the biggest and most extensive genus, containing small, inconspicuous wood mice which are common to the whole of the Philippines, while the other, more specialized genera are barely ever found outside Luzon. Apomys itself was divided into two groups, in the aforementioned article by Musser from 1982: the datae group, containing only A. datae, and the abrae-hylocetes group, containing all other species. Animals in these two groups differ in the way in which the head is supplied with blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
from arteries
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
. Since the publication of Musser's article, another species has been described that falls into the datae group: A. gracilirostris. This relationship is further supported by other similarities: both species are relatively large for the genus and have a relatively long snout.
In 2003, a phylogenetic study was published which compared DNA sequences from the cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
gene of thirteen species of Apomys. This study confirmed the proposed relationship between the Large Mindoro Forest Mouse (A. gracilirostris) and the Luzon Montane Forest Mouse (A. datae), as well as the status of the datae group as a sister group of the other species of Apomys.
The phylogenetic relationships of the Luzon Montane Forest Mouse can be summarized as follows.
According to this study, the split between the Luzon Montane Forest Mouse and the Large Mindoro Forest Mouse took place some three million years ago, as calculated using a molecular clock
Molecular clock
The molecular clock is a technique in molecular evolution that uses fossil constraints and rates of molecular change to deduce the time in geologic history when two species or other taxa diverged. It is used to estimate the time of occurrence of events called speciation or radiation...
, putting it in the pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
. It was also estimated that Apomys dates back more than four million years, with the Chromotys division being again more ancient by another two million years. Another, more elaborate study concluded that the Chromotys division was older still, at more than ten million years, and that the split between the Chromotys division and its closest relatives, a predominantly Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n group including Mus, Otomys
Otomys
African vlei rats , also known as groove-toothed rats, live in many areas of sub-Saharan Africa. They live in marshlands and grasslands, and eat the green grass and herbs that grow there, occasionally supplementing this with roots and seeds...
and Mastomys
Mastomys
Mastomys is a genus of rodent in the family Muridae.It contains the following species:* Awash Mastomys * Southern Multimammate Mouse * Guinea Multimammate Mouse...
, took place some sixteen million years ago. Seeing as Apomys probably originated on Luzon, The Luzon Montane Forest Mouse likely developed directly from the ancestor species of the datae group, while the Large Mindoro Forest Mouse is the result of a pliocene migration to Mindoro.
Identification
The genus Apomys, of which the Luzon Montane Forest Mouse is a member, can be identified by its small size, long tail, elongate, narrow hind feet, the presence of four abdominalAbdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
mammary glands, and a large number of skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
characteristics.
The Luzon Montane Forest Mouse is a large, thickset species with a tail that is about the same length as the body. The soft, thick dorsal fur is dark brown, while the ventral side of the body is a cream white. The hind feet are partly brown in colour on the dorsal side, but otherwise white. The tail is brown on the dorsal side, and a cream white ventrally. The animal has a large skull with a square-shaped neurocranium. Some of its skull characteristics are so special that they set the animal apart from most every other species of Apomys. One specimen has a head-torso-length of 143 mm, a tail length of 144 mm and a hind feet length of 34 mm. The specimens captured by Sanborn on Mount Data have a mean
Arithmetic mean
In mathematics and statistics, the arithmetic mean, often referred to as simply the mean or average when the context is clear, is a method to derive the central tendency of a sample space...
skull length of 39.2 mm (37.0 to 40.6 mm with a standard deviation
Standard deviation
Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...
of 1.1 mm). The Luzon Montane Forest Mouse's holotype has a skull length of 39.9 mm; that of A. major has a length of 38.4 mm.
The animal has a karyotype of 2n=44 and FN=54, which consists of five pairs of four-armed chromosomes and sixteen pairs of two-armed (telocentric) chromosomes. The X-chromosome is a large, and the Y-chromosome a small telocentric chromosome. This karyotype has much in common with that of the Least Forest Mouse
Least Forest Mouse
The Least Forest Mouse is a species of rodent in the family Muridae.It is found only in the Philippines....
(Apomys musculus), while at the same time being very different from the karyotypes of species form other parts of the Philippines (the karyotype of the Large Mindoro Forest Mouse, on a side note, is unknown).
Sources
- Baillie, J. 1996. Apomys datae. 2006 IUCN Red List of Threatened Species. Downloaded on 19 July 2007.
- Musser, G.G. & Heaney, L.R. 1992. Philippine rodents: definitions of Tarsomys and Limnomys plus a preliminary assessment of phylogenetic patterns among native Philippine murines (Murinae, Muridae). Bulletin of the American Museum of Natural History 211:1-138.
- Jansa, S.A., Barker, K.F. & Heaney, L.R. 2006. The pattern and timing of diversification of Philippine endemic rodents: Evidence from mitochondrial and nuclear gene sequences. Systematic Biology 55(1):73-88.
- Steppan, S.J., Zawadzki, C. & Heaney, L.R. 2003. Molecular phylogeny of the endemic Philippine rodent Apomys (Muridae) and the dynamics of diversification in an oceanic archipelago. Biological Journal of the Linnean Society 80:699-715.