Cricetomyinaepouched rats

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Diversity

Cricetomyinae, also known as pouched rats and mice, is an Old World group of nesomyid rodents. This subfamily contains eight species in three genera (Beamys, Cricetomys, and Saccostomus), divided between two tribes. (Musser and Carleton, 2005)

Geographic Range

Cricetomyines are native to sub-sarahan Africa. (Carleton and Musser, 1984)

Habitat

Cricetomyines live in savannahs, agricultural fields, sandy plains, scrub forests, moist woodlands, and forests. They are found at elevations from sea level to 2,100 meters. (Carleton and Musser, 1984; Nowak, 1999)

Physical Description

Cricetomyines range in length from 98 mm to 450 mm, and their tails measure 30 to 450 mm. The length of the tail is less than or equal to the length of the body. Pouched rats weigh anywhere from 40 g to almost 3 kg. Male Cricetomys are larger than female Cricetomys, but sexual dimorphism has not been reported for the other genera. Cricetomyines have robust bodies with large heads and short limbs. These rodents get their common name from their large cheek pouches. The ears are rounded and may be short or very large and nearly naked. The thick tail is naked or covered with short hairs and the eyes are relatively small. The strong hind feet have short toes. The pelage may be long and dense or short, coarse, and sleek, and it is gray or brown on the dorsal surface of the animal and white, gray, or buff-colored below. The soles of the feet are hairless.

The cricetomyine dental formula is 1/1, 0/0, 0/0, 3/3 = 16. The upper incisors are ungrooved, and the molars are rooted and cuspidate. There are accessory stylids on the labial side of the lower molars and accessory styles on the lingual side of the upper molars. The chevron-shaped enamel ridges of the molars are not joined by longitudinal mures or murids. There is a circular posteromedial cusp on the first and second lower molars. The mandibular ramus is relatively deep. The rostrum is long, and the area between the orbits is shaped like an hourglass. There is a slight notch and spine formed from the zygomatic plate. The jugal is large and composes most of the zygomatic arch. The malleus is of parallel construction. (Carleton and Musser, 1984; Nowak, 1999)

  • Sexual Dimorphism
  • sexes alike
  • male larger

Reproduction

The mating system of cricetomyines has not been reported.

Some cricetomyines breed year round (e.g., Cricetomys), and others breed only during the rainy season (e.g. Beamys). Litter sizes range from 1 (Cricetomys gambianus) to 10 (Saccostomus campestris). Gestation lasts from 22 to 32 days, the young open their eyes at about three weeks, and they are weaned at five to six weeks. Young pouched rats reach sexual maturity at seven to nine months. (Carleton and Musser, 1984; Nowak, 1999)

Female cricetomyines build nests where they give birth to their young and nurse them for five to six weeks. (Nowak, 1999)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The record longevity of a pouched rat in captivity is 7 years, 10 months. Cricetomyines in the wild undoubtedly live much shorter lives. (Nowak, 1999)

Behavior

Cricetomyines are nocturnal rodents, only occasionally foraging during the day. They are mainly terrestrial, but some climb and forage in trees and shrubs. On the ground, they walk with a slow, ambling gait. They build nests out of dry vegetation and place them in rock crevices, hollow trees, or in simple burrows situated among rocks. These simple burrows range from one to nine meters in length and are about 60 cm below the soil surface. Burrows contain chambers for storing food. Pouched rats have also been known to make use of burrows constructed by other animals. Cricetomyines are usually solitary, but males and females sometimes build their nests fairly close to one another. (Carleton and Musser, 1984; Nowak, 1999)

Communication and Perception

Cricetomyines communicate with one another through a range of complex vocalizations. They rely most on their senses of smell and hearing, as their eyes are fairly small, and if forced out into the daylight they behave as if nearly blind. (Carleton and Musser, 1984; Nowak, 1999)

Food Habits

These rodents are herbivorous or omnivorous, eating fruit, seeds, nuts, berries, roots, bulbs, crabs, snails, and sometimes insects. Coprophagy is known to occur in this group. Pouched rats hoard food in their large cheek pouches and carry it back to their burrows to store. (Carleton and Musser, 1984; Nowak, 1999)

Predation

Small mammalian carnivores, owls, snakes and humans are the most important cricetomyine predators. These animals probably rely on their vigilance, agility, and nocturnal habits to evade predation. (Carleton and Musser, 1984)

Ecosystem Roles

Cricetomyines have roles as primary and secondary consumers, and they are a food source for other mammals. Because of their habit of storing seeds, it is likely that cricetomyines also have a role in seed dispersal. Finally, cricetomyines are hosts for various flea species, including Xenopsylla crinita, Xenopsylla tortus, Xenopsylla sarodes, Dinopsyllus semnus, as well as a parasitic earwig, Hemimerus vosseleri, and numerous ticks. (Hubbard, 1972; Nowak, 1999)

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Some native tribes hunt and eat Cricetomys gambianus, and this species is sometimes kept as a pet by rodent enthusiasts. (Nowak, 1999)

Economic Importance for Humans: Negative

In some cities and towns, Cricetomys gambianus has become commensal with humans, living in sewers along with Rattus where it is also considered a pest. Also, cricetomyines carry the plague in some areas. (Hubbard, 1972; Nowak, 1999)

  • Negative Impacts
  • injures humans
    • carries human disease

Conservation Status

The two Beamys species are currently listed as near threatened by the IUCN, due to human-induced habitat loss and degradation. (IUCN, 2004)

  • IUCN Red List [Link]
    Not Evaluated

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Allison Poor (author), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coprophage

an animal that mainly eats the dung of other animals

endothermic

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.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

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).

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

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.

savanna

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.

temperate grassland

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.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Carleton, M., G. Musser. 1984. Muroid rodents. Pp. 289-379 in S Anderson, J Jones Jr., eds. Orders and Families of Recent Mammals of the World. New York: John Wiley and Sons.

Chaline, J., P. Mein, F. Petter. 1977. Les grandes lignes d'une classification évolutive des Muroidea. Mammalia, 41: 245-252.

Corti, M., R. Castiglia, F. Annesi, W. Verheyen. 2004. Mitochondrial sequences and karyotypes reveal hidden diversity in African pouched mice (subfamily Cricetomyinae, genus Saccostomus). Journal of Zoology, 262: 413–424.

Ellerman, J. 1941. The Families and Genera of Living Rodents, vol. II. London: British Museum (Natural History).

Hubbard, C. 1972. Observations on the life histories and behavior of some small rodents from Tanzania. Zoologica Africana, 7(2): 419-449.

IUCN, 2004. "2004 IUCN Red List of Threatened Species" (On-line). Accessed May 27, 2005 at www.redlist.org.

Jansa, S., M. Weksler. 2004. Phylogeny of muroid rodents: relationships within and among major lineages as determined by IRBP gene sequences. Molecular Phylogenetics and Evolution, 31: 256-276.

Michaux, J., A. Reyes, F. Catzeflis. 2001. Evolutionary history of the most speciose mammals: Molecular phylogeny of muroid rodents. Molecular Biology and Evolution, 18(11): 2017-2031.

Musser, G., M. Carleton. 1993. Family Muridae. Pp. 501-753 in D Wilson, D Reeder, eds. Mammal Species of the World. Washington, D.C.: Smithsonian Institution Press.

Musser, G., M. Carleton. 2005. Superfamily Muroidea. D Wilson, D Reeder, eds. Mammal Species of the World. Baltimore and London: The Johns Hopkins University Press.

Nowak, R. 1999. Walker's Mammals of the World, vol. 2. Baltimore and London: The Johns Hopkins University Press.

Petter, F. 1966. Affinités des genres Beamys, Saccostomus et Cricetomys (Rongeurs, Cricetomyinae). Annales du Musée Royal de l'Afrique Centrale, ser. 8 (Sciences Zoologiques), 144: 13-25.

Roberts, A. 1951. The Mammals of South Africa. South Africa: Central News Agency.

Simpson, G. 1945. The principles of classification and a classification of mammals. Bulletin of the American Museum of Natural History, 85: 1-350.

Steppan, S., R. Adkins, J. Anderson. 2004. Phylogeny and divergence-date estimates of rapid radiations in muroid rodents based on multiple nuclear genes. Systematic Biology, 53(4): 533-553.

Thomas, O. 1896. On the genera of rodents: an attempt to bring up to date the current arrangement of the order. Proceedings of the Zoological Society of London: 1012-1028.