Monodelphis glirinaAmazonian red-sided opossum

Geographic Range

Amazonian red-sided opossums are native to the Amazonian rainforests of Southeast Peru, Brazil and Northern Bolivia and is primarily found near the Southern Amazonian River and west of Xingu River. They have been found in the following states in Brazil: Acre, Rondonia, Amazonas, Mato Grosso and Para. Monodelphis glirina is sympatric in parts of its range with Monodelphis emiliae, Monodelphis brevicaudata and Monodelphis saci. (Castilheiro and Santos Filho, 2013; Pavan, et al., 2014; Pavan, et al., 2017; Pine and Handley,, 2008; Voss, et al., 2012)


Amazonian red-sided opossums are terrestrial, semi-fossorial and generally limited to below 1500 m elevation, but have been reported up to 2200 m. Amazonian red-sided opossums are occupy rainforest lowlands and open rainforests near river banks. Trees present in the habitat they occupy include palms Mauritia flexuosa and Jessenia bataua, as well as dominant bamboo species, Guadua sarcocarpa and Gaadua weberbaueri. Specific trees and vegetation used by M. glirina are not yet described. (Anderson, 1997; Daly and Mitchell, 2000; Pavan, et al., 2014; Pine and Handley,, 2008; Vidigal, 2014; Voss, et al., 2012)

  • Range elevation
    0 to 2200 m
    0.00 to 7217.85 ft

Physical Description

The genus Monodelphis is small relative to other species of didelphid opossums. Species in this genus have large claws with a reduced, non-opposable pollex and lack a marsupium and guard hairs. They have wide nasals and premolars that increase in size from front to back, as well as a medial vagina that is elongated anteriorly.

Amazonian red-sided opossums are characterized by longitudinal tricolor pelage patterns with reddish-orange flanks that fade to gray-yellow, although geographical variation occurs among populations. Fur on the tail covers less than 1/6th of the length of the tail. Monodelphis glirina individuals are larger and have sharper contrast of the longitudinal pelage stripes than in the closely related species, Monodelphis sanctaerosae. (Pavan, et al., 2012; Pine and Handley,, 2008; Vidigal, 2014; Voss, et al., 2001; Voss, et al., 2012)

The skull of M. glirina is characterized by incomplete auditory bullae, long and slender palataine foramen, short upper canines and large molars and an intermediate constriction of the interorbital - postorbital region. M. glirina, as well as other species of the M. brevicaudata species complex have elongated maxillopalatine fenestrae, no secondary foramen ovale, less distinct sagital crests and rostral processes, well defined nuchal lines, broad rostrums and triangular stapes with large obturator foramen. Skull measurements for M. glirina specifically are as follows: condylobasal length average: 38.0mm (range 35.7-40.8), nasal length: 18.3mm (16.5-20.6mm), nasal breadth: 5.8mm (5.1-6.4mm), zygomatic breadth: 20.5mm (18.9-22.4mm), least interorbital breadth: 5.9mm (18.9-22.4mm), palatal length: 21.0 mm (19.7-22.3 mm), palatal breadth: 12.5mm (11.7-13.2 mm), maxillary toothrow length: 15.4 mm (15.0-16.0mm), length of molars: 8.1 mm (8.0-8.2mm), length from M1-M3: 6.9mm (6.7-7.0mm), width of M3: 2.8mm (2.7-3.0mm). The Monodelphis brevicaudata species complex is also characterized by dorsal fur approximately 8mm long and shorter, bicolored ventral fur (4mm). In general, M. glirina have orange-red flanks and a gray-orange ventrum. The dorsal pelage is characterized by a gray-brown stripe that fades to the red-orange flanks. The pelage of the head is orange laterally and grey dorsally. Monodelphis glirina can be distinguished from its sister species, M. palliolata, from its upper row of molars that are greater than 7.9 mm length and geographical location. The dental formula for M. glirina has not yet been established, however the general dental formula for opossums is 5/4, 1/1, 3/3, 4/4 = 50. (Kozawa, et al., 1998; Pavan, et al., 2012; Pine and Handley,, 2008)

Populations of Amazonian red-sided opossums occurring in moist forests are more boldly patterned than populations inhabiting mineral crops, with red-orange colored flanks and grey coloring on the middle of the dorsal pelage. Mineral crop-dwelling populations have more pale pelage with less distinct contrast between colors. Species east of the Xingu river lack the characteristic middorsum stripe. (Pavan, et al., 2014)

Amazonian red-sided opossums are sexually dimorphic, with males larger than females. The head-body length of females ranges from 130 to 148 mm, and, in males, it ranges from 138 to 162 mm. Females weigh 49 to 55 g and males weigh 83 to 53 g. Age and reproductive status was not examined in this data set. However, the relative weight and body length differs between the sexes at different age classes in a closely related species, Monodelphis domestica. Females and males were not dimorphic until age class three (of seven observed age classes; age classes undefined). At age class four, males had the same body length as females but were heavier (average weight of males 57 g, females 50 g). By age class five, males were larger than females in all aspects (average male weight and head-body length: 73 g and 144 mm, respectively; average female weight and head-body length: 54 g and 133 mm). (Bergallo and Cerquiera, 1994; Voss, et al., 2012)

  • Sexual Dimorphism
  • male larger
  • Range mass
    24.4 to 79.6 g
    0.86 to 2.81 oz
  • Range length
    151.5 to 213.3 mm
    5.96 to 8.40 in


There is insufficient data for on reproduction in M. glirina. However, seasonal breeding is present in Monodelphis dimidiata. Within the genus, there is insufficient data on the mating systems of these opossums. (Bergallo and Cerquiera, 1994; Fadem, et al., 2010; Harder and Jackson, 2010)

The genus Monodelphis contains both iteroparous and semelparous species, although there is no information on this topic for M. glirina. However, generalizations can be made based on closely related species. M. glirina appears to be solitary in the wild, suggesting induced ovulation. In the closely related species, Monodelphis domestica, estrus is induced via contact with the secretions of the suprasternal gland of the males. Females will remain anestrus if the secretions of this gland are not encountered. Females in Monodelphis domestica are capable of producing two litters per breeding season, with 2 to 16 embryos per litter (mean of 7.9), but not all may survive to birth. Gestation is approximately 15 days and implantation occurs on the twelfth day. Divergence of male and female sex organs occurs 4 to 16 days post birth. In a less closely related species, Monodelphis dimidiata, young are weaned at 60 days and reach sexual maturity at 5 to 7 months. Young are altricial, as is typical of marsupials, and first open their eyes around 5 to 6 weeks of age. (Bergallo and Cerquiera, 1994; Fadem, et al., 2010; Harder and Jackson, 2010; Pine, et al., 1985)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • viviparous
  • Breeding interval
    Breeding in the closely related species Monodelphis domestica can occur up to two times in a year.
  • Breeding season
    Breeding in the closely related species Monodelphis domestica occurs from summer through the end of winter during the rainy season.
  • Range number of offspring
    16 (high)
  • Average number of offspring
  • Average gestation period
    15 days
  • Average weaning age
    8 weeks
  • Average age at sexual or reproductive maturity (female)
    5-7 months
  • Average age at sexual or reproductive maturity (male)
    5-7 months

Little parental investment beyond lactation is characteristic of marsupials in general. The extent of parental investment is unknown for Monodelphis glirina. Reproductive investment in the closely related Monodelphis domestica is well-studied. Sexual maturity is reached at 5 to 7 months and young are weaned around 60 days post-birth. Males do not invest in reproduction beyond insemination. (Bergallo and Cerquiera, 1994; Keyte and Smith, 2008)

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


The closely related Monodelphis domestica has been reported to live to 2.5 to 3 years in captivity. There is no data on the lifespan of Amazonian red-sided opossums in captivity or in the wild. (Keyte and Smith, 2008)

  • Average lifespan
    Status: captivity
    2.5-3 years


The genus Monodelphis is solitary and has varied activity patterns. There are diurnal, nocturnal and crepuscular species within the genus, and no specific data on activity patterns exists for Amazonian red-sided opossums. Monodelphis species sometimes cannibalize young days after birth and are a good model for research due to their small size and docile nature. These opossums become accustomed to humans quickly. Amazonian red-sided opossums are terrestrial, cursorial, predatory and exhibit moderate-high daily feeding behaviour. Unlike other opossumms, Monodelphis species do not live in trees. (Keyte and Smith, 2008; Pavan, et al., 2014; Pine and Handley,, 2008; Pine, et al., 1985; Steiner and Catzeflis, 2004)

Home Range

There is no data on the home range of Amazonian red-sided opossums.

Communication and Perception

Males and females of the closely related Monodelphis domestica scent mark their environment to communicate with potential mates. Males are perceptive to secretions from skin glands and urine of females and females are only receptive to secretions from the suprasternal gland of males. (Fadem, et al., 2010; Harder and Jackson, 2010)

Food Habits

Amazonian red-sided opossums are opportunistic, generalist omnivores. Insects (primarily beetles, but also grasshoppers and cicadas, true bugs, and millipedes) are a large part of the diet. Seeds and plant material have also been noted in the diet. (Castilheiro and Santos Filho, 2013)

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


There is no information on predators of Monodelphis species in the literature.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Monodelphis species are terrestrial predators that influence insect populations (specifically beetles) via direct predation. Amazonian red-sided opossums are generalist omnivores that have high metabolisms and are likely to modify their habitats through the removal of plants, seeds, and insects. (Anderson, 1997; Castilheiro and Santos Filho, 2013)

The gastrointestinal tract of Amazonian red-sided opossums has been found to contain nematodes in low quantities, indicating a low intensity of parasitism. These parasites are the only recorded parasites of M. glirina, however two ectoparasites were noted on the sister species of M. glirina, Monodelphis palliolata, including a chewing louse and a species of mite. (Castilheiro and Santos Filho, 2013; Pine and Handley,, 2008)

Commensal/Parasitic Species
  • mites (Gigantolaelaps aitkeni) has been observed in the sister to M. glirina, M. palliolata.
  • chewing lice (Cummingsia peramydis) have been observed in the sister to M. glirina, M. palliolata.
  • nematodes (Nematoda)

Economic Importance for Humans: Positive

Monodelphis species are used in research on genome sequencing and domestication. They are easy to study due to their small size and docile nature. They are model organisms for studies pertaining to melanoma, spinal cord injury, cholesterol influences on genetics, and olfactory responses to chemicals. (Keyte and Smith, 2008)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

There are no known adverse effects of M. glirina on humans.

Conservation Status

Amazonian red-sided opossums are listed as Least concern in the IUCN Redlist and have not been evaluated by CITES.

Other Comments

Amazonian red-sided opossums were first described by JA Wagner (1842) under the name Didelphis glirina. Some past literature referred to M. glirina as a subspecies of Monodelphis brevicaudata - Monodelphis brevicaudata brevicaudata, due to similar physical descriptions. It is now known that they are genetically distinct from Monodelphis brevicaudata. The Monodelphis brevicaudata species complex includes 7 species: M. brevicaudata, M. glirina, M. domestica, M. palliolata, M. maraxina, M. arlindoi and M. brevicaudata. There is evidence that Monodelphis maraxina may not be its own species, but instead a phenotypic variant of Monodelphis glirina. Cytochrome b sequences suggest that there are at least two different lineages within the species Monodelphis glirina. (Anderson, 1997; Pavan, et al., 2014; Pavan, et al., 2012)


Danielle Cayer (author), University of Manitoba, Jane Waterman (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.


uses smells or other chemicals to communicate


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.


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.


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.


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


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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