The subfamily Nesomyinae is a diverse group of muroid rodents endemic to Madagascar. There are 23 nesomyine species in nine genera. (Musser and Carleton, 2005)
Nesomyines live in a wide variety of habitats, including grasslands, wet meadows, sandy coastal forests, dry scrublands, and wet or dry inland forests. They range from sea level to 2,400 meters in elevation. (Carleton and Musser, 1984; Nowak, 1999)
Nesomyines are characterized by their morphological and ecological diversity. Typically they are medium to large gerbil-like, vole-like, or rat-like rodents. They measure 80 to 350 mm in head and body length and their tails range from 60 to 250 mm. Nesomyines weigh 21 to 1,500 grams. In some species, females weigh less than males, in other species, there is no sexual dimorphism. Nesomyine tails are short to long, naked to moderately furred, and sometimes tufted. Some have prehensile tails. The hind feet range from wide and short to narrow and long, and most have no hair on the soles. The pelage is long and soft or thick and woolly. It is sandy brown, reddish, or gray on the dorsum and yellowish white, white, or gray on the venter. Most nesomyines have large eyes and prominent ears and whiskers.
The nesomyine dental formula is 1/1, 0/0, 0/0, 3/3 = 16. The incisors are opisthodont. The molars are rooted, have a biserial cusp arrangement, and range from brachydont to hypsodont. In most species, the third molar is equal in size to the first two molars. Nesomyines have strong zygomatic arches with large jugals. Most species have ventrally constricted infraorbital foramina. There is a prominent interparietal bone. The bony palate is wide and smooth and bears one pair of posterior palatine foramina. The pterygoid fossae are flat and level with the bony palate. Most species have a large postglenoid foramen, and all species have an accessory tympanum and malleus of parallel construction. Nesomyines have 13 thoracic and 7 lumbar vertebrae. There are three circumvallate papillae on the tongue, and the stomach consists of a single chamber. The soft palate bears three premolar and five intermolar ridges. (Carleton and Musser, 1984; Nowak, 1999)
The reproductive behavior of some nesomyine species is entirely unknown. Therefore, the following may or may not apply to the entire group. Nesomyines reproduce during the wet season, and some species have just a single litter per year. Gestation lasts up to 138 days and there are one to four young per litter. Sexual maturity is not reached until the age of two years in some species. (Nowak, 1999; Sommer, 2000)
Female nesomyines nurse their offspring for up to six weeks in a sheltered spot such as a tree cavity or underground nest chamber. In monogamous species, males may risk predation themselves by keeping watch for danger and protecting their offspring. Also, in those species that live in family groups, such as Hypogeomys antimena, young females remain with their parents for more than a year, not dispersing until after their parents have a new litter. (Sommer, 2000)
The lifespan of nesomyines has not been reported.
Nesomyines are a diverse group, including terrestrial and arboreal rodents. They are modified for cursorial, scansorial, and saltatorial locomotion. They build nests in tree cavities or in underground burrows. These burrows may be quite complex with multiple entrances and chambers. Some nesomyines live in small family groups, with an adult pair and their offspring inhabiting one burrow system. These family groups are territorial, excluding strangers from their home ranges. Other species have permanent home ranges that overlap with one another. Most nesomyines are nocturnal, though a few species are diurnal, crepuscular, or active any time of the night or day. (Carleton and Musser, 1984; Nowak, 1999; Sommer, 2000)
Nesomyines probably sense their environment through vision, hearing, touch, smell, and taste, as do most mammals. Many have large eyes and ears and long vibrissae, suggesting keen visual, auditory, and tactile abilities. Some nesomyine species live in small family groups and give alarm calls to warn their offspring when predators approach. (Nowak, 1999; Sommer, 2000)
These rodents are herbivores that feed on fruit, seeds, berries, roots, and stems. They are not known to cache their food. (Nowak, 1999)
Nesomyines are primary consumers that provide food for upper level consumers such as carnivorous mammals and snakes. They are parasitized by nematodes and ticks. (Durette-Desset, et al., 2002; Hoogstraal, et al., 1967; Sommer, 2000)
There are no known positive effects of nesomyines on humans.
There are no known negative effects of nesomyines on humans.
This subfamily consists of endemic species with restricted ranges that are highly vulnerable to habitat loss. As a result, 8 of the 23 species in this group are on the IUCN's Red List of Threatened Species. Two of these species are critically endangered (Eliurus penicillatus and Macrotarsomys ingens), two are endangered (Eliurus majori and Hypogeomys antimena), one is vulnerable (Gymnuromys roberti), and three are lower risk (Brachyuromys betsileoensis, Brachyuromys ramirohitra, and Eliurus webbi). One species, the endangered Malagasy giant rat (Hypogeomys antimena), is being bred and studied in captivity at the Jersey Zoo by the Durrell Wildlife Conservation Trust. (Durrell Wildlife Conservation Trust, 2005; IUCN, 2004)
Tanya Dewey (editor), Animal Diversity Web.
Allison Poor (author), University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
active at dawn and dusk
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
animals that live only on an island or set of islands.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
specialized for leaping or bounding locomotion; jumps or hops.
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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