Monodelphis emiliaeEmilia's short-tailed opossum

Geographic Range

Monodelphis emiliae occurs in the South American Amazonian region of eastern Brazil, northeastern Perú and Bolivia. (Patton, et al., 2000; Pavan and Voss, 2016)


The genus Monodelphis is terrestrial and semifossorial. Emilia’s short-tailed opossum is a habitat generalist, and occurs in terra firme forests, areas of secondary vegetation, areas with primary forest and in swampy forests. (Patton, et al., 2000; Pavan and Voss, 2016; Voss, et al., 2019)

Physical Description

Emilia’s short-tailed opossum is small bodied with a relatively short tail (approximately 50mm). Body lengths of males ranged from 180 to 221 mm and the body length of one female specimen was 170 mm. The body mass of males ranged from 40-72g (n=6) and of females ranged from 20-35g (n=2), which suggests sexual dimorphism.

They have small feet with no pollex. Pelage is described as a rich brown to rufous or fulvous on the dorsal surface with grizzled grey necks and a rose-colored ventral surface with overtones of purple. The coloration and patterns are considered unique to this particular genus. Ears are short and rounded and described to have minute hairs. The muzzle is evenly conical with long nasals that extend backwards. Dental formula for members of the Didelphidae family typically follow 5/4, 1/1, 3/3, 4/4 = 50.

A distinguishing characteristic of M. emiliae from others in the genus is the fusion or contact between the thenar (medial tarsal pad) and first interdigital pads of the hind foot. The thenar and first interdigital are unfused in other members. The small subsquamosal foramen is also characteristically unique to M. emiliae as it is distinctly larger in other members of Monodelphis.

Emilia’s short-tailed opossum is also sympatric with Monodelphis adusta, Monodelphis saci, Monodelphis glirina and Monodelphis touan. Species can be distinguished externally by the dorsal pelage coloration and patterns. Monodelphis adusta has brown uniform coloration, it is smaller than M.emiliae with a nearly naked tail. Monodelphis saci is much smaller than M.emiliae and lacks a patterned dorsal pelage which is a uniform brownish color with red highlights on the head. Monodelphis glirina and M. touan have reddish flanks with distinct grizzled gray or brown dorsal patterning. (Eisenberg, 1989; Patton, et al., 2000; Pavan and Voss, 2016; Pavan, et al., 2017; Pine and Handley, 1984; Solari, 2007; Thomas, 1912; Voss, et al., 2019)

  • Sexual Dimorphism
  • male larger
  • Range mass
    20 to 72 g
    0.70 to 2.54 oz
  • Range length
    170 to 221 mm
    6.69 to 8.70 in


The mating system of M. emiliae is currently unknown.

Little is known about the reproduction of M. emiliae; however, members of the genus have bimodally distributed estrus cycles with estrus cycles lasting 5.9 days. Members of the genus can mate year-round in the lab.

Copulation lasts approximately 2 hours in genus Monodelphis with gestation lasting 14-15 days. Monodelphis brevicaudata, a relative of M. emiliae, can have up to 6 young per litter which may be a similar case for M. emiliae. However, litter size in Didelphids is often limited by the number of mammae available, which may vary by species. In M. emiliae mammae number ranges from 5-9.

Young are born altricial with neonates weighing between 0.07-0.1g at birth. Lactation can last 6-8 weeks with young firmly attached to a nipple for the first two weeks. Around 2-5 weeks of age, young are able to open their eyes. In Monodelphis domestica young are weaned between 49-56 days old. Both males and females in the genus Monodelphis reach sexual maturity around six months. (Hayssen, et al., 1993; Pavan and Voss, 2016)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Breeding interval
    Members in the genus Monodelphis can breed year round in the lab
  • Range number of offspring
    5 to 9
  • Average age at sexual or reproductive maturity (female)
    6 months
  • Average age at sexual or reproductive maturity (male)
    6 months

Females invest in parental care in M. emiliae through the investment in lactation and protection of the young until they are old enough to care for themselves. (Hayssen, et al., 1993)

  • Parental Investment
  • altricial
  • female parental care
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female


The life span of M.emiliae is currently unknown.


The behavior of M. emiliae is not known; however, members of the genus Monodelphis are typically solitary, show high levels of aggression and may show either crepuscular, diurnal or nocturnal activity. Monodelphis adusta which is sympatric with M. emiliae are assumed to be less arboreal than other opossums. (Eisenberg, 1989; Feldhamer, et al., 2015; Solari, 2007)

Home Range

The home range of M.emiliae is currently unknown.

Communication and Perception

Communication and perception of M. emiliae are not known, however Monodelphis domestica in the lab show signs of scent marking and vocalization which may be similar for M. emiliae. Vocalizations such as screeching occur when threatened or approached by a potential mate. Olfaction in M. domestica also play a role in territorial marking and for the assessment of reproductive status. (Fadem and Corbett, 1997)

Food Habits

Not much is known about Emilia’s short-tailed opossums’ diet; however, their diet may be similar to other opossum species, such as Monodelphis dimidiata and Monodelphis glirina which are opportunistic generalists. As opportunistic generalists they eat primarily insects but they may switch to other sources when insects are not abundant. (Busch and Kravetz, 1991; Castilheiro and dos Santos Filho, 2013)

  • Animal Foods
  • insects
  • terrestrial worms
  • Plant Foods
  • seeds, grains, and nuts


Details of predation on M.emiliae are not known. However, like other small mammals, they are likely preyed on by larger predatory mammals, birds, and snakes.

Ecosystem Roles

Emilia’s short-tailed opossum is a host for the Trypanosomatid parasite, Trypanosoma (Megatrypanum) saloboense which from a study suggests it is relatively host restricted. Saloboense is also found in M. brevicaudata. Monodelphis emiliae is also host to a new nematode in the family Oxyuridae, Monodelphoxyris dollmeiri. (Guerrero and Hugot, 2003; Lainson, et al., 2008)

Commensal/Parasitic Species
  • Trypanosoma (Megatrypanum) saloboense n. sp
  • Monodelphoxyris dollmeiri

Economic Importance for Humans: Positive

No known importance for humans.

Economic Importance for Humans: Negative

No known importance for humans.

Conservation Status

Under IUCN’s red list Emilia’s short tailed opossum is listed as least concern. However, the species may still be facing some forms of ecological threat, there are still many details about this mammal that are not well known which would warrant further investigation. (Patton and Percequillo, 2015)

Other Comments

Prior to Mondelphis emiliae, Emilia’s short tailed opossum went by several other taxonomic names which included: Peramys emiliae, Didelphis emiliae, Peramys tricolor emiliae, Monodelphis tricolor emiliae, Monodelphis touan emiliae, and Monodelphis touan. Recently, M. emiliae has been proposed under a new subgenus Pyrodelphys. (Gardner, 2007; Pavan and Voss, 2016)


Christie Lavallée (author), University of Manitoba, Annemarie van der Marel (editor), University of Manitoba, Tanya Dewey (editor), University of Michigan-Ann Arbor.



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

World Map


uses sound to communicate


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.


an animal that mainly eats meat


uses smells or other chemicals to communicate


active at dawn and dusk

  1. active during the day, 2. lasting for one day.

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


an animal that mainly eats seeds


An animal that eats mainly plants or parts of plants.


An animal that eats mainly insects or spiders.


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.


active during the night


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


chemicals released into air or water that are detected by and responded to by other animals of the same species


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.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them


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


lives alone


uses touch to communicate


Living on the ground.


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


uses sight to communicate


Busch, M., F. Kravetz. 1991. Diet composition of Monodelphis dimidiata (Marsupial: Didelphidae). Mammalia, 55(4): 619-621.

Castilheiro, W., M. dos Santos Filho. 2013. Diet of Monodelphis glirina (Mammalia: Didelphidae) in forest fragments in southern Amazon. Zoologia, 30(3): 249-254.

Eisenberg, J. 1989. Mammals of the neotropics, Volume 1: The northern neotropics: Panama, Colombia, Venezuela, Guyana, Suriname, French Guiana. Chicago: The University of Chicago Press.

Fadem, B., A. Corbett. 1997. Sex differences and the development of social behavior in a marsupial, the gray short-tailed opossum (Monodelphis Domestica). Physiology and Behavior, 61(6): 857-861.

Feldhamer, G., L. Drickamer, S. Vessey, J. Merritt, C. Krajewski. 2015. Mammology: adaptation, diversity, ecology. Baltimore, Maryland: Johns Hopkins University Press.

Gardner, A. 2007. Mammals of South America. Chicago: University of Chicago Press: 95-96.

Guerrero, R., J. Hugot. 2003. Monodelphoxyuris dollmeiri n. g., n. sp. (Nematoda: Oxyurida) from Monodelphis emiliae in Peru. Systematic Parasitology, 55: 73-79.

Hayssen, V., A. van Tienhoven, A. van Tienhoven. 1993. Asdell’s patterns of mammalian reproduction: A compendium of species-specific data. Ithaca, New York: Cornell University Press.

Lainson, R., F. Da Silva, C. Franco. 2008. Trypanosoma (Megatrypanum) Saloboense n. sp. (Kinetoplastida: Trypanosomatidae) parasite of Monodelphis emiliae (Marsupial: Didelphidae) from Amazonian Brazil. Parasite, 15: 99-103.

Patton, J., A. Percequillo. 2015. "Monodelphis emiliae. IUCN Red List of Threatened Species 2015" (On-line). Accessed October 31, 2019 at

Patton, J., M. Da Silva, J. Malcolm. 2000. Mammals of the Rio Juruá and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244: 306.

Pavan, S., A. Mendes-Oliveira, R. Voss. 2017. A New Species of Monodelphis (Didelphimorphia: Didelphidae) from the Brazilian Amazon. American Museum Novitates, 3872: 20.

Pavan, S., R. Voss. 2016. A revised subgeneric classification of short-tailed opossums (Didelphidae: Monodelphis). American Museum Novitates, 3868: 44.

Pine, R., C. Handley. 1984. A review of the Amazonian short-tailed opossum Monodelphis emiliae (Thomas). Mammalia, 48(2): 239-245.

Solari, S. 2007. New species of Monodelphis (Didelphimorphia: Didelphidae) from Peru, with notes on M. adusta (Thomas, 1897). Journal of Mammology, 88(2): 319-329.

Thomas, O. 1912. On small mammals from the lower Amazon. Annals and Magazine of the Natural History, Zoology, Botany, and Geology, 8(9): 84-90.

Voss, R., D. Fleck, S. Jansa. 2019. Mammalian diversity and Matses ethnomammalogy in Amazonian Peru Part 3: Marsupials (Didelphimorphia). Bulletin of the American Museum of Natural History, 432: 87.