Marmosa andersoniAnderson's mouse opossum

Geographic Range

Marmosa andersoni is only known from three localities in the Andean foothills of southeastern Peru (Cusco department). (Pine, 1972; Solari and Pine, 2008)


The only known habitat of Marmosa andersoni is premontane rainforest. (Solari and Pine, 2008)

  • Range elevation
    400 to 600 m
    1312.34 to 1968.50 ft

Physical Description

Like other species of mouse opossums, Marmosa andersoni is a small, pouchless marsupial with large, membranous ears; prominent eyes; a mask of dark fur surrounding the eyes; and a long, slender, prehensile tail. The dorsal fur is reddish-brown and the ventral fur is abruptly paler (whitish yellow with gray-based hairs). Among other diagnostic traits, this species differs from other members of the genus by its very large postorbital processes, very narrow interorbital region, and by having two rows of long silvery hairs on the underside of the tail (flanking the midventral naked prehensile surface). Only three adult specimens have been collected, so the known range of measurements and weights (below) do not represent the full range of morphometric variation in this species. (Pine, 1972; Solari and Pine, 2008)

  • Range mass
    28 to 38 g
    0.99 to 1.34 oz
  • Range length
    124 to 125 mm
    4.88 to 4.92 in


The mating system of this species is unknown.

Nothing has been published about reproduction in Anderson's mouse opossum, but other species of mouse opossum are spontaneous ovulators that give birth to highly altricial young after a short gestation (like Robinson's mouse opossum). Females have nine mammae, so the average litter size is unlikely to be larger than nine. (Solari and Pine, 2008)

  • Range number of offspring
    9 (high)

Although parental care has not been observed in this species, females presumably nurse neonatal young, groom them, and protect them from predators. ()

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


Nothing is known about the lifespan of this species.


Several juvenile individuals were found climbing in bamboo, and the morphology of the species is consistent with an arboreal or scansorial lifestyle. One adult was found inside a bamboo cane. Like other mouse opossums, this species is probably nocturnal and solitary. (Solari and Pine, 2008)

Communication and Perception

Communication has not been studied in this species, but adults of both sexes have sternal glands that probably have some social-marking function. (Solari and Pine, 2008)

The eyes, ears, nasal turbinates (thin bones that support olfactory epithelium), and tactile hairs (vibrissae) are well developed in this species (as in other opossums), so vision, hearing, and touch are presumably important senses. ()

Food Habits

The diet of this species is unknown, but its dentition is consistent with insectivory. Like other species of mouse opossums, this species may also be opportunistically frugivorous. ()

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit


The predators of this species are unknown but they probably include snakes, owls, and wild felids. ()

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The ecosystem roles of this species are unkown, but it probably eats small animals (e.g., insects). It probably is eaten by larger animals, and it is probably host to both internal and external parasites. Probable ectoparasites include species of Arachnida (Acari: mites) and Insecta (Siphonaptera: fleas). Probable endoparasites include species of Acanthocephala (spiny-headed worms), Cestoda (tapeworms), Digenea (flukes), and Nematoda (roundworms). ()

Commensal/Parasitic Species

Economic Importance for Humans: Positive

It is unlikely that this species is of any positive economic importance.

Economic Importance for Humans: Negative

There are no known adverse effects of Marmosa andersoni on humans.

Conservation Status

Although this species has a restricted geographic range, the region that they inhabit is still largely undeveloped.

Other Comments

Marmosa andersoni is one of the least frequently observed and most poorly known of all mouse opossums.


Robert Voss (author), American Museum of Natural History, Sharon Jansa (editor), American Museum of Natural History, Alexa Unruh (editor), Animal Diversity Web Staff.



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.


Referring to an animal that lives in trees; tree-climbing.

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


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.

female parental care

parental care is carried out by females


An animal that eats mainly insects or spiders.


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 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


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.


Pine, R. 1972. A new subgenus and species of murine opossum (genus Marmosa) from Peru. Journal of Mammalogy, 53: 279-282.

Solari, S., R. Pine. 2008. Rediscovery and redescription of Marmosa (Stegomarmosa) andersoni Pine (Mammalia: Didelphimorphia: Didelphidae), an endemic Peruvian mouse opossum, with a reassessment of its affinities. Zootaxa, 1756: 49-61.