Large Mindoro Forest Mouse
Encyclopedia
The Large Mindoro Forest Mouse (Apomys gracilirostris) 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 montane
s. The Large Mindoro Forest Mouse is a large mouse with large feet, a long tail and an elongated snout which is morphologically
unique within its genus. It is covered in soft fur which is mostly dark brown in colour. Its closest relative is thought to be the Luzon Montane Forest Mouse
, based on genetic
and morphological similarities.
, on the island Mindoro
. To this day, these animals, all captured between May 28 and June 12, 1992, remain the only known specimens of this species.
In 1995, in the scientific journal Proceedings of the Biological Society of Washington, biologist Luis. A. Ruedas described the animal as Apomys gracilirostris. At the time it was the ninth known species of the endemic Filipino genus Apomys, and the second found on Mindoro, after Apomys musculus
(Least Forest Mouse). The editors of a compilation work on the indigenous mammals of the Philippines accepted the animal as a new species in 1998.
A. gracilirostris was the first newly described Apomys since 1962, when Apomys sacobianus
(Long-nosed Luzon Forest Mouse) was described. However, it was far from being the only new species discovered in the Philippines. Several new rodents had already been discovered in the eighties, one of which was actually from Mindoro as well (Anonymomys mindorensis
or Mindoro Climbing Rat). A constant supply of new species remained in the years after the description of A. gracilirostris. In ten years time, eight new mammal species were added to the list. In 2006, another new Apomys was described: Apomys camiguinensis
(Camiguin Forest Mouse). Apomys also comprises several species which are as of yet undescribed, two of which are from Mindoro. Another species from Mindoro, from the predominantly Indonesia
n genus Maxomys
, has yet to receive its scientific name.
In accordance with the International Code of Zoological Nomenclature
, the name Apomys gracilirostris is a binomen
. The generic name
, Apomys was proposed by American
biologist Edgar Mearns in 1905 and has the meaning of "mouse from Mount Apo
" (mys, μῦς, being the Ancient Greek
word for "mouse"); this because the type species
of the genus was first found on Mount Apo. The specific name, gracilirostris, is a combination of the Latin
words gracilis "slender" and rostrum "snout" and refers to the animal's long, slender snout.
mammary glands, and a large number of skull
characteristics. Within this genus, the Large Mindoro Forest Mouse has several specific identifying features, the most important of which are its very thin and short upper incisor
s, long lower incisors and long snout. The tail and feet are also relatively long, even within the genus Apomys. The characteristics of the incisors are so peculiar that when Ruedas discovered the species, he initially thought he had found a new genus.
The fur of the Large Mindoro Forest Mouse is soft and smooth. The hairs of the dorsal
fur are light gray near the root, and dark brown at the tip. Between the normal hairs are many black tactile hairs. This makes the dorsal fur appear dark brown, although recently captured animals have a dark blue-green hue. Some animals are darker around the midline of the back, and all are a lighter colour at the flanks. The colour of the ventral fur varies between animals, with it being a yellow-brown colour in some, slightly lighter coloured than the dorsal fur in others, still others having gray hairs with brown or silver-coloured tips in the ventral fur, and finally some animals showing no difference between the dorsal and ventral fur at all.
The tail is usually an even, dark colour, but in some animals the ventral side is somewhat darker. In some animals the tail ends in a white tip of 2 to 10 mm in length. The tail has fourteen scales
per centimeter. The long, dark hind feet end in long claws (about 4 mm). The claws on the front feet are about 3 mm in length. The animal has seven cervical vertebrae
, thirteen thoracic vertebrae
, six lumbar vertebrae
, three sacral vertebrae
and thirty-two to thirty-five caudal vertebrae.
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 in two groups by American biologist Guy Musser
in 1982, the first being the datae group, containing only the Luzon Montane Forest Mouse (A. datae), and the second 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
. Ruedas placed the Large Mindiro Forest Mouse in the datae group. 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).
The phylogenetic relationships of the Large Mindoro Forest Mouse can be summarized as follows.
This study also found that the Large Mindoro Forest Mouse was the only Apomys species that displayed deep within-species divergences, which were calculated to date back some 400.000 years. The split between the Large Mindoro Forest Mouse and the Luzon Montane Forest Mouse dates back further still at an estimated three million years ago, putting it in the Pliocene
. Apomys itself in turn was found to date back more than four million years, while the Chromotys division was estimated to go back another two million years. These dates were all calculated using a molecular clock
.
Another, more elaborate phylogenetic study on all of the endemic Filipino genera and species of Murinae
, of which the Large Mindoro Forest Mouse is a member, produced different results. According to this study, the Chromotys division originated some ten million years ago (rather than the estimate of six million years ago from the previous study). It was further calculated that the split between the Chromotys division and its closest relatives, a predominantly Africa
n group including Mus
, Otomys
and Mastomys
, had happened about sixteen million years ago. However, since the fossil record
of Murinae from the Philippines is non-existent, and controversial for Murinae from other areas, these estimates can only be based on the molecular clock, and not on direct paleontological
data.
The Large Mindoro Forest Mouse is the third known rodent endemic to Mindoro, after the Mindoro Black Rat
and the Mindoro Climbing Rat
, and not including the Ilin Island Cloudrunner
, the occurrence of which has not been confirmed on the island. However, in a compilation work on the indigenous mammals of the Philippines, published in 1998, it was announced that there is a second Apomys on Mindoro. This species has yet to be described and has temporarily been given the name of "Apomys sp. E". It may be related to two other undescribed species from Sibuyan Island
and Greater Negros-Panay
, Apomys sp. A/C and Apomys sp. B. The local population of A. musculus, the only other Apomys known on the island, may also represent a separate species. Several other species occur exclusively on Mindoro (in addition to the undescribed Maxomys species mentioned earlier), including Oliver's Warty Pig
, the Tamaraw
and the megabat
Styloctenium mindorensis. The relatively large number of endemic species on Mindoro can be explained from the fact that, in all probability, Mindoro was never connected to any other landmass. This enabled the animals present on the island to develop in isolation from their relatives.
A remarkable biogeographical
aspect of Mindoro is its status as a transition area between Greater Palawan
and the rest of the Philippines. On the one hand, species like Oliver's Warty Pig and the Tamaraw are clearly related to animals from Greater Palawan and the rest of South-East Asia, but on the other, Mindoro also harbours animals from genera like Apomys and Chrotomys, which are clearly Filipino. The latter animals reached Mindoro from Luzon, or possibly in some cases Greater Negros-panay. The Large Mindoro Forest Mouse, with its close relationship to the Luzon Montane Forest Mouse, probably falls into the group of animals that reached the island from Luzon.
The Large Mindoro Forest Mouse has been found at three different sites in the municipality of San Teodoro
, on the North flank of Mount Halcon. These sites are located at altitudes between 1,255 and 1,900 m (4,117 and 6,234 ft). There is a good possibility, however, that the Large Mindoro Forest Mouse also occurs on other mountains on Mindoro, especially on the northern part of the island, which is home to large areas of undamaged cloud forest
.
The lowest forests in which the Large Mindoro Forest Mouse has been found, at some 1,250 m (4,101 ft) above sea level, are mostly between 14 and 16 m (46 and 52 ft) in height, with the very tallest reaching 20 m (66 ft). The dominant species of tree are from the genera Leptospermum flavescens, Tristaniopsis
and Lithocarpus
, from the families Myrtaceae
and Fagaceae
. These very humid forests have a dense understory vegetation, which consists, amongst other plants, of moss
es, tree ferns
and species of Pandanus
. At higher altitudes (between 1,600 and 1,950 m (5,249 and 6,398 ft)), the forest is dominated by bamboo
, while the only tree species present is Agathis philippinensis
. Here, vegetation reaches a height between 7 and 10 m (23 and 33 ft). There are many smaller plants present, such as fern
s, orchids and species of Pandanus. The forest floor is covered with a layer of leaves with a thickness between 6 and 8 cm (2.4 and 3.1 in).
Nothing is known with any certainty about the behaviour of the Large Mindoro Forest Mouse. The long snout, small upper incisors and long lower incisors suggest that the animal feeds on soft invertebrate
s, but this is not certain. Furthermore, the long tail and elongated hind feet with well-developed claws point towards a climbing lifestyle.
Very little is also known about the animal's procreation habits. A female specimen was found to carry three embryo
s. Another female had a swollen uterus
, and testicle
s were visible in several of the male specimens.
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 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 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 is found 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...
. Its natural habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
is subtropical or tropical moist montane
Montane
In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...
s. The Large Mindoro Forest Mouse is a large mouse with large feet, a long tail and an elongated snout which is morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
unique within its genus. It is covered in soft fur which is mostly dark brown in colour. Its closest relative is thought to be the Luzon Montane Forest Mouse
Luzon Montane Forest Mouse
The Luzon Montane Forest Mouse 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 . It is most closely related to the Large Mindoro Forest Mouse, which occurs on Mindoro...
, based on genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and morphological similarities.
Discovery and taxonomy
In May and June 1992, an expedition to the Philippines was organised for the purpose of increasing the knowledge on their biodiversity. During this expedition, sixteen examples of a then unknown species of mouse were captured on Mount HalconMount Halcon
Mount Halcon is a mountain located in the island of Mindoro in the Philippines. Its height of 2,586 meters makes it the 18th highest peak in the Philippines. Its slopes has earned it the title to be the most difficult mountain to climb in the country.Mt. Halcon is home to the indigenous Alangan...
, on the island 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:...
. To this day, these animals, all captured between May 28 and June 12, 1992, remain the only known specimens of this species.
In 1995, in the scientific journal Proceedings of the Biological Society of Washington, biologist Luis. A. Ruedas described the animal as Apomys gracilirostris. At the time it was the ninth known species of the endemic Filipino genus Apomys, and the second found on Mindoro, after Apomys musculus
Least Forest Mouse
The Least Forest Mouse is a species of rodent in the family Muridae.It is found only in the Philippines....
(Least Forest Mouse). The editors of a compilation work on the indigenous mammals of the Philippines accepted the animal as a new species in 1998.
A. gracilirostris was the first newly described Apomys since 1962, when Apomys sacobianus
Long-nosed Luzon Forest Mouse
The Long-nosed Luzon Forest Mouse is a species of rodent in the family Muridae.It is found only in the Philippines.Its natural habitat is subtropical or tropical dry forests.It is threatened by habitat loss.-References:...
(Long-nosed Luzon Forest Mouse) was described. However, it was far from being the only new species discovered in the Philippines. Several new rodents had already been discovered in the eighties, one of which was actually from Mindoro as well (Anonymomys mindorensis
Mindoro Climbing Rat
The Mindoro Climbing Rat or Mindoro Rat is a species of rodent in the family Muridae.It is found only in the Philippines. It is the only species in the genus Anonymomys....
or Mindoro Climbing Rat). A constant supply of new species remained in the years after the description of A. gracilirostris. In ten years time, eight new mammal species were added to the list. In 2006, another new Apomys was described: Apomys camiguinensis
Least Philippine Forest Mouse
The Camiguin Forest Mouse, Apomys camiguinensis is a forest mouse endemic to the island of Camiguin in the Philippines. It has large ears and eyes, a long tail and rusty-brown fur, and it feeds mostly on insects and seeds...
(Camiguin Forest Mouse). Apomys also comprises several species which are as of yet undescribed, two of which are from Mindoro. Another species from Mindoro, from the predominantly Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n genus Maxomys
Maxomys
Maxomys is a genus of mice, widespread in Southeast Asia. They are mid-sized rodents, similar to rats, that live on the ground of tropical rainforests. There they build nests, padded with fallen leaves from trees. They feed on roots, fallen fruit, and other plants, as well as insects...
, has yet to receive its scientific name.
In accordance with the International Code of Zoological Nomenclature
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
, the name Apomys gracilirostris is a binomen
Binomen
In zoological nomenclature, a binomen , is the two-part name of a species. The term was introduced in 1953, abolishing the previously used "binomial name" . A binomen consists of a generic name and a specific epithet...
. The generic name
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 was proposed by American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
biologist Edgar Mearns in 1905 and has the meaning of "mouse from Mount Apo
Mount Apo
Mount Apo is a large solfataric, potentially-active stratovolcano in the island of Mindanao, Philippines. With an altitude of , it is the highest mountain in the country and is located between Davao City and Davao del Sur province in Region XI and Cotabato province in Region XII...
" (mys, μῦς, being the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
word for "mouse"); this because the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus was first found on Mount Apo. The specific name, gracilirostris, is a combination of the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
words gracilis "slender" and rostrum "snout" and refers to the animal's long, slender snout.
Identification
The genus Apomys, of which the Large Mindoro Forest Mouse is a member, can be identified by its small size, a 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. Within this genus, the Large Mindoro Forest Mouse has several specific identifying features, the most important of which are its very thin and short upper incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s, long lower incisors and long snout. The tail and feet are also relatively long, even within the genus Apomys. The characteristics of the incisors are so peculiar that when Ruedas discovered the species, he initially thought he had found a new genus.
| Measurement | 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... | Females (four specimens) | Males (thirteen specimens) |
|---|---|---|---|
| Total length (mm) | 294 | 306,2 ± 23,21 (283-330) | 314,1 ± 30,98 (288-398) |
| Tail length (mm) | 157 | 161,2 ± 12,61 (147-175) | 159,0 ± 14,50 (135-185) |
| Hind foot length (mm) | 39 | 36,5 ± 3,70 (33-41) | 38,8 ± 3,05 (34-45) |
| Ear length (mm) | 21 | 19,2 ± 1,26 (18-21) | 18,6 ± 2,72 (14-22) |
| Weight (g) | 80 | 88,8 ± 17,97 (75-115) | 87,4 ± 18,28 (71-140) |
The fur of the Large Mindoro Forest Mouse is soft and smooth. The hairs of the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
fur are light gray near the root, and dark brown at the tip. Between the normal hairs are many black tactile hairs. This makes the dorsal fur appear dark brown, although recently captured animals have a dark blue-green hue. Some animals are darker around the midline of the back, and all are a lighter colour at the flanks. The colour of the ventral fur varies between animals, with it being a yellow-brown colour in some, slightly lighter coloured than the dorsal fur in others, still others having gray hairs with brown or silver-coloured tips in the ventral fur, and finally some animals showing no difference between the dorsal and ventral fur at all.
The tail is usually an even, dark colour, but in some animals the ventral side is somewhat darker. In some animals the tail ends in a white tip of 2 to 10 mm in length. The tail has fourteen scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
per centimeter. The long, dark hind feet end in long claws (about 4 mm). The claws on the front feet are about 3 mm in length. The animal has seven cervical vertebrae
Cervical vertebrae
In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...
, thirteen thoracic vertebrae
Thoracic vertebrae
In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
, six lumbar vertebrae
Lumbar vertebrae
The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body...
, three sacral vertebrae
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
and thirty-two to thirty-five caudal vertebrae.
Evolution and phylogenetic relationships
The Large Mindoro 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
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...
, 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
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...
. Apomys itself was divided in two groups by American biologist 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...
in 1982, the first being the datae group, containing only the Luzon Montane Forest Mouse (A. datae), and the second 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....
. Ruedas placed the Large Mindiro Forest Mouse in the datae group. 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
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...
study was published which compared 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...
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).
The phylogenetic relationships of the Large Mindoro Forest Mouse can be summarized as follows.
This study also found that the Large Mindoro Forest Mouse was the only Apomys species that displayed deep within-species divergences, which were calculated to date back some 400.000 years. The split between the Large Mindoro Forest Mouse and the Luzon Montane Forest Mouse dates back further still at an estimated three million years ago, 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...
. Apomys itself in turn was found to date back more than four million years, while the Chromotys division was estimated to go back another two million years. These dates were all 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...
.
Another, more elaborate phylogenetic study on all of the endemic Filipino genera and species of Murinae
Murinae
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...
, of which the Large Mindoro Forest Mouse is a member, produced different results. According to this study, the Chromotys division originated some ten million years ago (rather than the estimate of six million years ago from the previous study). It was further calculated 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
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...
, 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...
, had happened about sixteen million years ago. However, since the fossil record
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
of Murinae from the Philippines is non-existent, and controversial for Murinae from other areas, these estimates can only be based on the molecular clock, and not on direct paleontological
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
data.
The Large Mindoro Forest Mouse is the third known rodent endemic to Mindoro, after the Mindoro Black Rat
Mindoro Black Rat
The Mindoro Black Rat is a species of rodent in the family Muridae.It is found only in the Philippines.-References:* Baillie, J. 1996. . Downloaded on 19 July 2007....
and the Mindoro Climbing Rat
Mindoro Climbing Rat
The Mindoro Climbing Rat or Mindoro Rat is a species of rodent in the family Muridae.It is found only in the Philippines. It is the only species in the genus Anonymomys....
, and not including the Ilin Island Cloudrunner
Ilin island cloudrunner
The Ilin Island Cloudrunner is a critically endangered, possibly extinct cloud rat from Ilin Island in the Philippines. It is a fluffy-coated, bushy-tailed rat and may have emerged from tree hollows at night to feed on fruits and leaves...
, the occurrence of which has not been confirmed on the island. However, in a compilation work on the indigenous mammals of the Philippines, published in 1998, it was announced that there is a second Apomys on Mindoro. This species has yet to be described and has temporarily been given the name of "Apomys sp. E". It may be related to two other undescribed species from Sibuyan Island
Sibuyan Island
Sibuyan is a crescent-shaped island of Romblon Province, Philippines. It has an area of 445 km². The island has two prominent peaks, Mount Guiting-Guiting with a height of 2,058 m and Mount Nailog with a height of 789 m...
and Greater Negros-Panay
Ecoregions in the Philippines
The Philippine archipelago is one of the world's great reservoirs of biodiversity and endemism. The archipelago includes over 7000 islands, and a total land area of 300,780 km²....
, Apomys sp. A/C and Apomys sp. B. The local population of A. musculus, the only other Apomys known on the island, may also represent a separate species. Several other species occur exclusively on Mindoro (in addition to the undescribed Maxomys species mentioned earlier), including Oliver's Warty Pig
Oliver's Warty Pig
Oliver's Warty Pig , or Mindoro Warty Pig is a small species of pig which can only be found on the island of Mindoro in the Central Philippines. This species previously treated to be a subspecies of S...
, the Tamaraw
Tamaraw
The Tamaraw or Mindoro Dwarf Buffalo is a small, hoofed mammal belonging to the family Bovidae. It is endemic to the island of Mindoro in the Philippines and is the only endemic Philippine bovine. It is believed, however, to have once also thrived on the greater island of Luzon...
and the megabat
Megabat
Megabats constitute the suborder Megachiroptera, family Pteropodidae of the order Chiroptera . They are also called fruit bats, old world fruit bats, or flying foxes.-Description:...
Styloctenium mindorensis. The relatively large number of endemic species on Mindoro can be explained from the fact that, in all probability, Mindoro was never connected to any other landmass. This enabled the animals present on the island to develop in isolation from their relatives.
A remarkable biogeographical
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
aspect of Mindoro is its status as a transition area between Greater Palawan
Ecoregions in the Philippines
The Philippine archipelago is one of the world's great reservoirs of biodiversity and endemism. The archipelago includes over 7000 islands, and a total land area of 300,780 km²....
and the rest of the Philippines. On the one hand, species like Oliver's Warty Pig and the Tamaraw are clearly related to animals from Greater Palawan and the rest of South-East Asia, but on the other, Mindoro also harbours animals from genera like Apomys and Chrotomys, which are clearly Filipino. The latter animals reached Mindoro from Luzon, or possibly in some cases Greater Negros-panay. The Large Mindoro Forest Mouse, with its close relationship to the Luzon Montane Forest Mouse, probably falls into the group of animals that reached the island from Luzon.
Ecology and behaviour
| Number (CMNH) | Number (PNM) | Date | Site | Altitude | Sex and other data |
|---|---|---|---|---|---|
| 634 | 3475 | - | 3 | app. 1,900 m (6,234 ft) | Male |
| 635 | 3476 | - | 3 | app. 1,900 m (6,234 ft) | Female |
| 636 | - | - | 3 | app. 1,900 m (6,234 ft) | Female |
| 637 | 3477 | - | 3 | app. 1,900 m (6,234 ft) | Male |
| 639 | - | - | 3 | app. 1,900 m (6,234 ft) | Male |
| 640 | - | - | 3 | app. 1,900 m (6,234 ft) | Male |
| 641 | 3478 | - | 3 | app. 1,900 m (6,234 ft) | Male |
| 642 | - | May 28 | 2 | app. 1,255 m (4,117 ft) | Young male |
| 643 | 3439 | June 1 | 2 | app. 1,255 m (4,117 ft) | Adult female |
| 644 | - | June 4 | 1 | app. 1,580 m (5,184 ft) | Young male |
| 645 | - | June 7 | 1 | app. 1,580 m (5,184 ft) | Young male |
| 646 | - | June 7 | 1 | app. 1,700 m (5,577 ft) | Adult female |
| 647 | - | June 9 | 1 | app. 1,700 m (5,577 ft) | Young adult male |
| 648 | 3480 | June 10 | 1 | app. 1,700 m (5,577 ft) | Adult male |
| 649 | 3481 | June 11 | 1 | app. 1,700 m (5,577 ft) | Old male |
| 650 | 3482 | June 12 | 1 | app. 1,580 m (5,184 ft) | Adult male (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... ) |
The Large Mindoro Forest Mouse has been found at three different sites in the municipality of San Teodoro
San Teodoro, Oriental Mindoro
San Teodoro is a 4th-class municipality in the province of Oriental Mindoro, Philippines. According to the 2010 Census of Population and Housing, it has a total population of 15,039, household population of 15,027, and 3,281 households...
, on the North flank of Mount Halcon. These sites are located at altitudes between 1,255 and 1,900 m (4,117 and 6,234 ft). There is a good possibility, however, that the Large Mindoro Forest Mouse also occurs on other mountains on Mindoro, especially on the northern part of the island, which is home to large areas of undamaged cloud forest
Cloud forest
A cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and...
.
The lowest forests in which the Large Mindoro Forest Mouse has been found, at some 1,250 m (4,101 ft) above sea level, are mostly between 14 and 16 m (46 and 52 ft) in height, with the very tallest reaching 20 m (66 ft). The dominant species of tree are from the genera Leptospermum flavescens, Tristaniopsis
Tristaniopsis
Tristaniopsis is a genus of 40 species of shrub and tree in the myrtle family Myrtaceae. They have a wide distribution, ranging from Burma, Thailand, Malesia, New Caledonia and Australia.Species include:*Tristaniopsis lucida...
and Lithocarpus
Lithocarpus
Lithocarpus is a genus in the beech family Fagaceae, differing from Quercus in the erect male spikes. The World Checklist accepts 334 species, though some other texts suggest as few as 100 species. About 100 Asian species of the genus were formerly treated in the genus Pasania. All but one are...
, from the families Myrtaceae
Myrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...
and Fagaceae
Fagaceae
The family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like nuts. Fagaceous leaves are often...
. These very humid forests have a dense understory vegetation, which consists, amongst other plants, of moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es, tree ferns
Cyatheales
The order Cyatheales is a taxonomic division of the fern subclass, Cyatheatae, which includes the tree ferns. No clear morphological features characterize all of the Cyatheales, but DNA sequence data indicates that the order is monophyletic. Some species in the Cyatheales have tree-like growth...
and species of Pandanus
Pandanus
Pandanus is a genus of monocots with about 600 known species. They are numerous palmlike dioecious trees and shrubs native of the Old World tropics and subtropics. They are classified in the order Pandanales, family Pandanaceae.-Overview:...
. At higher altitudes (between 1,600 and 1,950 m (5,249 and 6,398 ft)), the forest is dominated by bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
, while the only tree species present is Agathis philippinensis
Agathis philippinensis
Agathis philippinensis is a species of Agathis native to the Philippines, Sulawesi and Halmahera, where it occurs in upland tropical rainforest at 450-2,200 m altitude, rarely as low as 250 m in northern Luzon....
. Here, vegetation reaches a height between 7 and 10 m (23 and 33 ft). There are many smaller plants present, such as fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s, orchids and species of Pandanus. The forest floor is covered with a layer of leaves with a thickness between 6 and 8 cm (2.4 and 3.1 in).
Nothing is known with any certainty about the behaviour of the Large Mindoro Forest Mouse. The long snout, small upper incisors and long lower incisors suggest that the animal feeds on soft invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, but this is not certain. Furthermore, the long tail and elongated hind feet with well-developed claws point towards a climbing lifestyle.
Very little is also known about the animal's procreation habits. A female specimen was found to carry three embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s. Another female had a swollen uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
, and testicle
Testicle
The testicle is the male gonad in animals. Like the ovaries to which they are homologous, testes are components of both the reproductive system and the endocrine system...
s were visible in several of the male specimens.