Macrotarsomys petteri
Encyclopedia
Macrotarsomys petteri, also known as Petter's Big-footed Mouse, is a Malagasy
rodent in the genus Macrotarsomys
. With a head and body length of 150 mm (5.9 in) and body mass of 105 g (3.7 oz), Macrotarsomys petteri is the largest species of its genus. The upperparts are brown, darkest in the middle of the back, and the underparts are white to yellowish. The animal has long whiskers, short forelimbs, and long hindfeet. The tail ends in a prominent tuft of long, light hairs. The skull is robust and the molars
are low-crowned and cuspidate
.
Macrotarsomys petteri is now found only in the Mikea Forest
of southwestern Madagascar, but subfossil
records indicate that it was previously more widely distributed in southern Madagascar. Climatic changes and competition with introduced species may have led to the shift in its distribution. The Mikea Forest, the only place where it is still known to occur, is threatened by human development.
, a forest region of southwestern Madagascar, a single specimen of the rodent genus Macrotarsomys
was collected. This animal turned out to be distinct from both previously known species of the genus—Macrotarsomys bastardi, which is widespread in western Madagascar, and the larger Macrotarsomys ingens, known only from the Ankarafantsika National Park
. Accordingly, Steven Goodman
and Voahangy Soarimalala named it in 2005 as a new species, Macrotarsomys petteri. The specific name, petteri, honors French zoologist François Petter for his contributions to the study of Malagasy rodents. M. petteri, the largest species in the genus, is most similar to M. ingens, which may be its closest relative.
rodent with short forelimbs and long hindfeet. With a head and body length of 150 mm (5.9 in) and body mass of 105 g (3.7 oz) in the only known complete specimen, it is much larger than M. bastardi, and its measurements fall at or above the upper end of the known range of variation in M. ingens. The upperparts are covered with soft and short, brown fur. Most cover hairs (the main part of the fur) are dark brown for the two-thirds closest to the base, then light brown, with a short dark brown tip. The middle of the back appears darker, because the cover hairs there are entirely dark brown. The hairs are 6 to 8 mm (0.2 to 0.3 in) long on the shoulders and 7 to 9 mm (0.3 to 0.4 in) on the back. The guard hair
s are gray. Because the flanks lack entirely dark cover hairs, they are slightly lighter than the rest of the upperparts. They are sharply separated in color from the underparts, which are entirely white to buffish. The mystacial vibrissae (whiskers above the mouth) are long, up to 60 mm (2.4 in), and white or black in color. The pinnae (external ears) are dark brown and covered with fine gray hairs, and ear length is 32 mm (1.3 in).
Hindfoot length is 37 mm (1.5 in). The upper sides of the feet are covered with grayish white fur, which extends around the claws to form ungual tufts. On the hindfeet, the fifth digit is relatively short at 6 mm (0.2 in); the hallux (first digit) is 8 mm (0.3 in) long, and the other digits 11 to 12 mm (0.4 to 0.5 in). The tail is 238 mm (9.4 in) long and naked in part. At the base, it is dark brown both above and below, but slightly lighter below. The upper side remains dark brown for much of its length, though the color does become lighter towards the tip. The lower side becomes mottled at about 55 mm (2.2 in) from the tip and then whitish at about 65 mm (2.6 in). Macrotarsomys petteri has a well-developed tuft at its tail tip, consisting of whitish and occasional light brown hairs. This tuft commences at about 130 mm (5.1 in) from the base with fairly short hairs and becomes more pronounced at 180 mm (7.1 in). In contrast, M. ingens has a weaker, dark brown tuft.
Macrotarsomys petteri has a large and robust skull with well-developed zygomatic arch
es (cheekbones). The interorbital region
of the skull (between the eyes) is smooth, as in M. ingens, and lacks the shelves characteristic of M. bastardi. The palate
is broad and the incisive foramina (openings in the front portion of the palate) are long and broad. In the mandible
(lower jaw), the root of the lower incisor
is housed in a distinct capsular process
, a protuberance at the back of the jawbone. The lower masseteric ridge (a crest on the outer side of the mandible) is prominent. As is typical of Macrotarsomys, the molars
are cuspidate and low-crowned.
(Rattus rattus), several species of tenrecs, and the shrew Suncus madagascariensis. Although only a single individual of M. petteri was caught during Goodman and Soarimalala's survey, which accrued 3100 trap-nights, they argue that this does not necessarily mean the species is rare, since trapping rates for rodents in the dry forests of Madagascar are often variable depending on year and season. Nothing is known of its behavior, but the animal's morphology suggests it lives on the ground.
Subsequent to its discovery at the Mikea Forest, Macrotarsomys petteri was also found as a subfossil
in cave deposits at Andrahomana in far southeastern Madagascar, a find reported in 2006. There, it was found together with more abundant remains of the introduced black rat and house mouse
(Mus musculus), as well as indigenous rodents such as Macrotarsomys bastardi. Two M. petteri bones were radiocarbon dated to 790–410 BCE and 150–390 CE, respectively, a period when the local climate became drier and humans first appeared. Macrotarsomys species are thought to burrow in sandy ground and would not be expected to enter caves; therefore, the subfossils are probably remains of animals eaten by birds of prey. Although M. petteri could conceivably persist in remnant pockets of wet habitat in southeastern Madagascar, searches at two sites near Andrahomana failed to confirm its presence. It may have become locally extinct in the area because of the drying climate and competition with the black rat.
In 2009, Macrotarsomys petteri was also recorded from the cave of Ankilitelo in southwestern Madagascar. Remains of a large Macrotarsomys had previously been reported from other southern Madagascar sites, and at least some of these may be M. petteri. A karst
ic deposit near Lake Tsimanampetsotsa
(dated to the Late Pliocene
or Early Pleistocene
on unclear grounds) contained three species of Macrotarsomys, including a very large one that may well be M. petteri. Remains identified as Macrotarsomys ingens have been reported from a cave at Ankazoabo
in southern Madagascar; these may also be M. petteri.
assesses Macrotarsomys petteri as "Data Deficient
", but notes that the species will very probably qualify as threatened if its current distribution turns out to be restricted to primary forest in the Mikea Forest. The Mikea Forest is one of the largest remaining forests of southwestern Madagascar, but it is not protected and is threatened by logging, pasture, and conversion to agricultural land.
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
rodent in the genus Macrotarsomys
Macrotarsomys
Macrotarsomys is a genus of rodent in the family Nesomyidae.It contains the following species:Genus Macrotarsomys - Big-footed mice*Bastard Big-Footed Mouse, Macrotarsomys bastardi Milne-Edwards and G. Grandidier, 1898...
. With a head and body length of 150 mm (5.9 in) and body mass of 105 g (3.7 oz), Macrotarsomys petteri is the largest species of its genus. The upperparts are brown, darkest in the middle of the back, and the underparts are white to yellowish. The animal has long whiskers, short forelimbs, and long hindfeet. The tail ends in a prominent tuft of long, light hairs. The skull is robust and the molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
are low-crowned and cuspidate
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
.
Macrotarsomys petteri is now found only in the Mikea Forest
Mikea Forest
The Mikea Forest is a forested region of southwestern Madagascar, between Manombo and Morombe. More specifically, it stretches from Route Nationale 9 to the west coast and from Mangoky south to the Manombo River...
of southwestern Madagascar, but subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
records indicate that it was previously more widely distributed in southern Madagascar. Climatic changes and competition with introduced species may have led to the shift in its distribution. The Mikea Forest, the only place where it is still known to occur, is threatened by human development.
Taxonomy
During a 2003 biological inventory of the Mikea ForestMikea Forest
The Mikea Forest is a forested region of southwestern Madagascar, between Manombo and Morombe. More specifically, it stretches from Route Nationale 9 to the west coast and from Mangoky south to the Manombo River...
, a forest region of southwestern Madagascar, a single specimen of the rodent genus Macrotarsomys
Macrotarsomys
Macrotarsomys is a genus of rodent in the family Nesomyidae.It contains the following species:Genus Macrotarsomys - Big-footed mice*Bastard Big-Footed Mouse, Macrotarsomys bastardi Milne-Edwards and G. Grandidier, 1898...
was collected. This animal turned out to be distinct from both previously known species of the genus—Macrotarsomys bastardi, which is widespread in western Madagascar, and the larger Macrotarsomys ingens, known only from the Ankarafantsika National Park
Ankarafantsika National Park
Ankarafantsika National Park is a National Park in the Boeny Region of Madagascar. The closest city is Majunga 115 km north of the park. Ankarafantsika is mostly tropical in climate type. The Sakalava people are the predominate ethnic group in the park. The rodent Macrotarsomys ingens occurs only...
. Accordingly, Steven Goodman
Steven Goodman
Steven Goodman is an American Conservation Biologist, and field biologist on staff in the Department of Zoology at the Field Museum of Natural History....
and Voahangy Soarimalala named it in 2005 as a new species, Macrotarsomys petteri. The specific name, petteri, honors French zoologist François Petter for his contributions to the study of Malagasy rodents. M. petteri, the largest species in the genus, is most similar to M. ingens, which may be its closest relative.
Description
Macrotarsomys petteri is a terrestrialTerrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
rodent with short forelimbs and long hindfeet. With a head and body length of 150 mm (5.9 in) and body mass of 105 g (3.7 oz) in the only known complete specimen, it is much larger than M. bastardi, and its measurements fall at or above the upper end of the known range of variation in M. ingens. The upperparts are covered with soft and short, brown fur. Most cover hairs (the main part of the fur) are dark brown for the two-thirds closest to the base, then light brown, with a short dark brown tip. The middle of the back appears darker, because the cover hairs there are entirely dark brown. The hairs are 6 to 8 mm (0.2 to 0.3 in) long on the shoulders and 7 to 9 mm (0.3 to 0.4 in) on the back. The guard hair
Guard hair
Guard hairs are the longest, coarsest hairs in a mammal's coat, forming the topcoat . They taper to a point and protect the undercoat from the elements. They are often water repellent and stick out above the rest of the coat...
s are gray. Because the flanks lack entirely dark cover hairs, they are slightly lighter than the rest of the upperparts. They are sharply separated in color from the underparts, which are entirely white to buffish. The mystacial vibrissae (whiskers above the mouth) are long, up to 60 mm (2.4 in), and white or black in color. The pinnae (external ears) are dark brown and covered with fine gray hairs, and ear length is 32 mm (1.3 in).
Hindfoot length is 37 mm (1.5 in). The upper sides of the feet are covered with grayish white fur, which extends around the claws to form ungual tufts. On the hindfeet, the fifth digit is relatively short at 6 mm (0.2 in); the hallux (first digit) is 8 mm (0.3 in) long, and the other digits 11 to 12 mm (0.4 to 0.5 in). The tail is 238 mm (9.4 in) long and naked in part. At the base, it is dark brown both above and below, but slightly lighter below. The upper side remains dark brown for much of its length, though the color does become lighter towards the tip. The lower side becomes mottled at about 55 mm (2.2 in) from the tip and then whitish at about 65 mm (2.6 in). Macrotarsomys petteri has a well-developed tuft at its tail tip, consisting of whitish and occasional light brown hairs. This tuft commences at about 130 mm (5.1 in) from the base with fairly short hairs and becomes more pronounced at 180 mm (7.1 in). In contrast, M. ingens has a weaker, dark brown tuft.
Macrotarsomys petteri has a large and robust skull with well-developed zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es (cheekbones). The interorbital region
Interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups....
of the skull (between the eyes) is smooth, as in M. ingens, and lacks the shelves characteristic of M. bastardi. The palate
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 separate. The palate is divided into two parts, the anterior...
is broad and the incisive foramina (openings in the front portion of the palate) are long and broad. In the mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
(lower jaw), the root of the lower incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
is housed in a distinct capsular process
Capsular process
In rodents, the capsular process or projection is a bony capsule that contains the root of the lower incisor. It is visible on the labial side of the mandible as a raising in the bone...
, a protuberance at the back of the jawbone. The lower masseteric ridge (a crest on the outer side of the mandible) is prominent. As is typical of Macrotarsomys, the molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
are cuspidate and low-crowned.
Distribution and ecology
The single known living specimen, a young adult male, was collected at 80 m (260 ft) altitude in the Andaladomo forest (part of the Mikea Forest). The Andaladomo forest is different in vegetation from the rest of the Mikea Forest, and is similar to forests further to the north on Madagascar. The animal was found in an isolated fragment of dry deciduous forest amid land cleared for maize cultivation. The trap was set at the foot of a tree surrounded by bushes and succulent plants. Other small mammals known from the Mikea Forest include Macrotarsomys bastardi, the introduced black ratBlack Rat
The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...
(Rattus rattus), several species of tenrecs, and the shrew Suncus madagascariensis. Although only a single individual of M. petteri was caught during Goodman and Soarimalala's survey, which accrued 3100 trap-nights, they argue that this does not necessarily mean the species is rare, since trapping rates for rodents in the dry forests of Madagascar are often variable depending on year and season. Nothing is known of its behavior, but the animal's morphology suggests it lives on the ground.
Subsequent to its discovery at the Mikea Forest, Macrotarsomys petteri was also found as a subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
in cave deposits at Andrahomana in far southeastern Madagascar, a find reported in 2006. There, it was found together with more abundant remains of the introduced black rat and house mouse
House mouse
The house mouse is a small rodent, a mouse, one of the most numerous species of the genus Mus.As a wild animal the house mouse mainly lives associated with humans, causing damage to crops and stored food....
(Mus musculus), as well as indigenous rodents such as Macrotarsomys bastardi. Two M. petteri bones were radiocarbon dated to 790–410 BCE and 150–390 CE, respectively, a period when the local climate became drier and humans first appeared. Macrotarsomys species are thought to burrow in sandy ground and would not be expected to enter caves; therefore, the subfossils are probably remains of animals eaten by birds of prey. Although M. petteri could conceivably persist in remnant pockets of wet habitat in southeastern Madagascar, searches at two sites near Andrahomana failed to confirm its presence. It may have become locally extinct in the area because of the drying climate and competition with the black rat.
In 2009, Macrotarsomys petteri was also recorded from the cave of Ankilitelo in southwestern Madagascar. Remains of a large Macrotarsomys had previously been reported from other southern Madagascar sites, and at least some of these may be M. petteri. A karst
KARST
Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
ic deposit near Lake Tsimanampetsotsa
Lake Tsimanampetsotsa
Lake Tsimanampetsotsa is a saline lake in the Toliara Province, southwestern part of Madagascar. It is located at around . The lake is an important wetland and it is protected within a national park and as a Ramsar site. Ramsar site has a total area of 456.00 km² while the surface of the lake is...
(dated to the Late 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...
or Early Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
on unclear grounds) contained three species of Macrotarsomys, including a very large one that may well be M. petteri. Remains identified as Macrotarsomys ingens have been reported from a cave at Ankazoabo
Ankazoabo
Ankazoabo is a town in Atsimo-Andrefana Region, Madagascar....
in southern Madagascar; these may also be M. petteri.
Conservation status
The IUCN Red ListIUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
assesses Macrotarsomys petteri as "Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
", but notes that the species will very probably qualify as threatened if its current distribution turns out to be restricted to primary forest in the Mikea Forest. The Mikea Forest is one of the largest remaining forests of southwestern Madagascar, but it is not protected and is threatened by logging, pasture, and conversion to agricultural land.
Literature cited
- Garbutt, N. 2007. Mammals of Madagascar: A Complete Guide. A & C Black, 304 pp. ISBN 978-0-7136-7043-1
- Goodman, S. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2010.2. <www.iucnredlist.org>. Downloaded on January 3, 2011.
- Goodman, S.M. and Soarimalala, V. 2005. A new species of Macrotarsomys (Rodentia: Muridae: Nesomyinae) from southwestern Madagascar (subscription required). Proceedings of the Biological Society of Washington 118(2):450–464.
- Goodman, S.M., Vasey, N. and Burney, D.A. 2006. The subfossil occurrence and paleoecological implications of Macrotarsomys petteri (Rodentia: Nesomyidae) in extreme southeastern Madagascar (subscription required). Comptes Rendus Palevol 5:753–762.
- Muldoon, K.M., De Blieux, D.D., Simons, E.L. and Chatrath, P.S. 2009. The subfossil occurrence and paleoecological significance of small mammals at Ankilitelo Cave, southwestern Madagascar (subscription required). Journal of Mammalogy 90(5):1111–1131.