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Monodelphis dimidiatasouthern short-tailed opossum

By Samuel Duskey

Geographic Range

Monodelphis dimidiata is native in northern Argentina, Paraguay, southern Brazil, and Uruguay (Gardner, 2007). (Gardner, 2007)

Habitat

Monodelphis dimidiata live in native grasslands of the region, but have been found in other habitats (Baladrón, 2012). (Baladrón, et al., 2012)

Physical Description

Monodelphis dimidiata is a small marsupial species. Their ventral side is yellowish and on their dorsal side is grayish, with short ears, they are sexually dimorphic, with the males larger than the females (Eisenberg 1989). Adult males body length is around 200 mm and weigh around 90 g, adult females body length is around 170 mm and weigh around 50 g (Baladrón 2012). (Baladrón, et al., 2012; Eisenberg, 1989)

  • Sexual Dimorphism
  • male larger
  • Range mass
    44.6 to 113.7 g
    1.57 to 4.01 oz
  • Average mass
    76.4 g
    2.69 oz
  • Range length
    163.5 to 225.2 mm
    6.44 to 8.87 in
  • Average length
    190.5 mm
    7.50 in

Reproduction

It is not known when Monodelphis dimidiata breed; however, because the males are known to die in the summer after they mate it is likely that they breed in the spring or early summer (Baladrón 2012). (Baladrón, et al., 2012)

Not a lot of information on Monodelphis dimidiata reproduction is known, only that they have one breeding season because they are semelparous. Adult males die shortly after breeding, and adult females die after nurturing their young (Baladrón 2012). It is likely the young are born small like other marsupials, and have a short gestation period. (Baladrón, et al., 2012; Eisenberg, 1989)

  • Range number of offspring
    16 (high)
  • Average number of offspring
    11

Little is known about the parental investment of Monodelphis dimidiata. Adult females do survive until their young have been weaned and it is likely none do not survive to mate in the next year (Baladrón 2012). Being semelparous and most adult males likely dying before their young have been born,it is likely that all parental investment is done by the females (Baladrón 2012). (Baladrón, et al., 2012)

Lifespan/Longevity

Being semelparous Monodelphis dimidiata only lives for about one year, males have shorter lifespans and die shortly after breeding, females die after rearing their young (Baladrón 2012). (Baladrón, et al., 2012)

  • Average lifespan
    Status: wild
    1 years

Behavior

Information on Monodelphis dimidiata is unknown but they are likely fossorial as they primarily are found in grasslands, they are also likely solitary like many other Didelphidae (Martina 2013). (Martina, 2013)

Home Range

The home range of Monodelphis dimidiata is unknown.

Communication and Perception

Monodelphis dimidiata uses smell as its main sense, it also makes vocal communication like other Didelphidae (González 2000).

Food Habits

Monodelphis dimidiata individuals primarily eat insects but have been known to eat arachnids, earthworms, isopods, and mollusks, it also has been reported to eat small mammals, and plants (Hume 1999). (González and Claramunt, 2000)

  • Animal Foods
  • mammals
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms

Predation

Little information is known about Monodelphis dimidiata anti-predator adaptations but since Monodelphis dimidiata lives primarily in grasslands, its grayish back likely provides some camouflage. Monodelphis dimidiata has been found in the stomachs of Barn Owls (Tyto alba) and White-tailed Kites (Elanus leucurus) (Scheibler 2007). (Scheibler, 2007)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Monodelphis dimidiata has a negative impact on the insects and other animals it eats, it also has a positive effect on the animals like Tyto alba and Elanus leucurus that have been known to eat Monodelphis dimidiata (González 2000). (González and Claramunt, 2000)

Economic Importance for Humans: Positive

There are no known positive effects of Monodelphis dimidiata on humans

Economic Importance for Humans: Negative

There are no known negative consequences of Monodelphis dimidiata on humans.

Conservation Status

This species is listed as Least Concern according to the IUCN Red List, but Monodelphis dimidiata has been reported to be in decline due to the loss of native grassland to agriculture (Brito et al., 2011). (Brito, et al., 2011)

Contributors

Samuel Duskey (author), Miami University, Joseph Baumgartner (editor), Miami University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

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

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

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.

female parental care

parental care is carried out by females

insectivore

An animal that eats mainly insects or spiders.

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.

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

sexual

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

solitary

lives alone

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 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.

References

Baladrón, A., A. Malizia, M. Bó, M. Liébana, M. Bechard. 2012. Population dynamics of the southern short-tailed opossum (Monodelphis dimidiata) in the Pampas of Argentina. Australian Journal of Zoology, 60/4: 238-245.

Brito, D., J. Vilela, D. Flores, P. Teta. 2011. "Monodelphis dimidiata" (On-line). The IUCN Red List of Threatened Species.. Accessed May 07, 2015 at http://www.iucnredlist.org/details/13693/0.

Eisenberg, J. 1989. Mammals of the Neotropics. Chicago: University of Chicago Press.

Gardner, A. 2007. Mammals of South America. Chicago: University of Chicago Press.

González, E., S. Claramunt. 2000. Behaviors of captive short-tailed opossums, Monodelphis dimidiata. Mammalia, 64/3: 271-286.

Hume, I. 1999. Marsupial Nutrition. New York: Cambridge University Press.

Martina, L. 2013. "Didelphidae American opossums and opossums" (On-line). Accessed May 05, 2015 at http://animaldiversity.org/accounts/Didelphidae/.

Scheibler, D. 2007. Habitat associations of small mammals in southern Brazil and use of regurgitated pellets of birds of prey for inventorying a local fauna.. Brazilian Journal Of Biology, 67/4: 619.

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