Large Mindoro forest mouse
Large Mindoro forest mouse | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Muridae |
Genus: | Apomys |
Species: | A. gracilirostris
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Binomial name | |
Apomys gracilirostris L.A. Ruedas, 1995
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Range of the large Mindoro forest mouse on global scale | |
Range of the large Mindoro forest mouse within the Philippines (red) |
The large Mindoro forest mouse (Apomys gracilirostris) is a species of
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 Halcon, 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
A. gracilirostris was the first newly described Apomys since 1962, when Apomys sacobianus (
In accordance with the
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
Measurement | Holotype | Females[6] (four specimens) |
Males[6] (thirteen specimens) |
---|---|---|---|
Total length (mm) | 294 | 306 ± 23 (283–330) | 314 ± 31 (288–398) |
Tail length (mm) | 157 | 161 ± 13 (147–175) | 159 ± 15 (135–185) |
Hind foot length (mm) | 39 | 37 ± 4 (33–41) | 39 ± 3 (34–45) |
Ear length (mm) | 21 | 19.2 ± 1.3 (18–21) | 19 ± 3 (14–22) |
Weight (g) | 80 | 89 ± 18 (75–115) | 87 ± 18 (71–140) |
The fur of the large Mindoro forest mouse is soft and smooth. The hairs of the
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
Evolution and phylogenetic relationships
The large Mindoro forest mouse belongs to the Chrotomys division, a group within the Murinae that occurs exclusively on the Philippines and in addition to Apomys also includes Rhynchomys, Chrotomys and Archboldomys. Animals in this division share several morphological[7] and genetic[8] 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).[9]
The phylogenetic relationships of the large Mindoro forest mouse can be summarized as follows.
Chrotomys division |
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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.[9] 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.[9] 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 African group including Mus, Otomys and Mastomys, had happened about sixteen million years ago.[8] 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
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.[11]
Ecology and behaviour
Number (CMNH)[12] |
Number (PNM)[12] |
Date | Site[13] | Altitude | Sex and other data |
---|---|---|---|---|---|
634 | 3475 | – | 3 | app. 1,900 m (6,200 ft) | Male |
635 | 3476 | – | 3 | app. 1,900 m (6,200 ft) | Female |
636 | – | – | 3 | app. 1,900 m (6,200 ft) | Female |
637 | 3477 | – | 3 | app. 1,900 m (6,200 ft) | Male |
639 | – | – | 3 | app. 1,900 m (6,200 ft) | Male |
640 | – | – | 3 | app. 1,900 m (6,200 ft) | Male |
641 | 3478 | – | 3 | app. 1,900 m (6,200 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 (5,180 ft) | Young male |
645 | – | June 7 | 1 | app. 1,580 m (5,180 ft) | Young male |
646 | – | June 7 | 1 | app. 1,700 m (5,600 ft) | Adult female |
647 | – | June 9 | 1 | app. 1,700 m (5,600 ft) | Young adult male |
648 | 3480 | June 10 | 1 | app. 1,700 m (5,600 ft) | Adult male |
649 | 3481 | June 11 | 1 | app. 1,700 m (5,600 ft) | Old male |
650 | 3482 | June 12 | 1 | app. 1,580 m (5,180 ft) | Adult male (holotype) |
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.[5]
The lowest forests in which the large Mindoro forest mouse has been found, at some 1,250 m (4,100 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 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 invertebrates, 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 embryos. Another female had a swollen uterus, and testicles were visible in several of the male specimens.
References
- IUCN (2016). "Apomys gracilirostris". IUCN Red List of Threatened Species. 2016. Retrieved 9 December 2016.
- ^ doi:10.5962/bhl.title.3419.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - Chrotomys sibuyanensis.
- ^ Musser & Carleton, 2005, pp. 1258, 1282, 1368
- ^ a b c d Ruedas, L.A. (1995). "Description of a new large-bodied species of Apomys Mearns, 1905 (Mammalia: Rodentia: Muridae) from Mindoro Island, Philippines". Proceedings of the Biological Society of Washington. 108 (2): 302–318.
- ^ minimum – maximum).
- ISSN 0003-0090.
- ^ PMID 16507525.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ doi:10.1111/j.1095-8312.2003.00274.x.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ Musser & Carleton, 2005, p. 1283
- ^ Musser and Carleton, 2005, p. 1282
- ^ Cincinnati Museum of Natural History (CMNH) in Cincinnati, but most have since been transferred to the National Museum of the Philippines(NMP). The numbers are catalogue numbers of these two institutes.
- ^ Site 1 is the North Ridge, 13°16′48″N 120°59′19″E / 13.28000°N 120.98861°E, known locally as "Hangló". Site 2 is the valley of the river Dulangan, 13°17′27″N 120°59′32″E / 13.29083°N 120.99222°E. Site 3 is known locally as "Patok-tok" and is located near site 1.
Bibliography
- "Apomys gracilirostris". The IUCN Red List of Threatened Species version 2009.1. IUCN. 2008. Retrieved 18 August 2009.
- Musser, G.G. 1982. Results of the Archbold Expeditions. No. 108. The definition of Apomys, a native rat of the Philippine islands. American Museum Novitates 2746:1–43.
- OCLC 62265494.