Most records of this species are from semideciduous and dry lowland forests, but it has also been collected in montane forest. It is sometimes reported to be more abundant at the edges of clearings and in secondary growth than in primary forest. (Alvizu and Aguilera, 1998; O'Connell, 1979; O'Connell, 1983; Rossi, et al., 2010)
Like other species of mouse opossums, 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 usually some shade of yellowish or grayish brown, and the ventral fur is typically pale yellowish or buffy. Among other diagnostic traits, this species differs from other species of Marmosa by having a short rostral process of the premaxillae, well-developed palatine fenestrae, and relatively large auditory bullae. This species is sexually dimorphic (males are larger than females). (Alvizu and Aguilera, 1998; Lopez-Fuster, et al., 2000; Rossi, et al., 2010)
Nothing definite seems to be known about the mating system or reproductive seasonality of this species. Previous reports about these aspects of reproductive biology of Marmosa isthmica). (Gutierrez, et al., 2010)were actually based on studies of other species (e.g.,
M. xerophila) are known to be seasonal breeders, and typically occurs in habitats with highly seasonal rainfall, so it is probably also a seasonal breeder. It is not known whether or not individuals of this species breed more than once in a lifetime, but some closely related species are known to be semelparous. (Barnes and Barthold, 1969; Barnes and Wolf, 1971; Godfrey, 1975; O'Connell, 1979; Rossi, et al., 2010)is a spontaneous ovulator that gives birth to very altricial young (about 0.1 g at birth) after a short (14 days) gestation. Eleven young (on average) were found attached to the nipples of females captured in trapping studies. The young remain attached to the mother's teats for 21 days and become fully independent after 60-70 days. Sexual maturity is reached after about 40 weeks but "full breeding behavior" is said to occur at about one year of age. Copulation occurs with the pair suspended by their tails from an overhead support. Although evidence from field studies of this species (e.g., O'Connell, 1979) is inconclusive, closely related species (such as
Females nurse the young for several weeks and presumably groom them and protect them from predators at the same time. (Barnes and Wolf, 1971)
Nothing definite seems to be known about the longevity of this species in the wild or in captivity, but other species of Marmosa are not thought to live much longer than one year in the wild. (Tate, 1933)
The behavior of this species (except as described above in the context of reproduction) has not been the focus of any published study, but trapping results suggest that it is nocturnal and arboreal or scansorial. (Alvizu and Aguilera, 1998; O'Connell, 1979)
The only field study focussed on the home range of this species obtained estimates of about 2.5 hectares for each sex using the minimum convex polygon method. (Alvizu and Aguilera, 1998)
Mating is preceeded by hissing and chirping sounds that presumably communicate sexual or agressive intentions. Adult males possess a gular gland that presumably has some social scent-marking funtion. The eyes, ears, nasal turbinates (thin bones that support olfactory epithelium), and tactile hairs are well developed in this species (as in other opossums), so vision, hearing, and touch are probably important senses. (Barnes and Barthold, 1969; Rossi, et al., 2010)
There has been no study of the food habits of this species in the wild, but captives seem to do best when insects and fruit are provided daily. The dental morphology of Marmosa species, is consistent with a mainly insectivorous diet. (Godfrey, 1975), like that of other
insects). It is probably eaten by snakes, owls, and carnivorans; and it is certainly host to many species of invertebrate ecto- and endo-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).is probably a primary consumer (of fruit) and a secondary consumer (of
This species is not known to be of any positive economic importance for humans.
There are no known adverse effects ofon humans.
There has been much taxonomic confusion about this species. For the first half of the 20th century, it was known as Marmosa mitis (a junior synonym). Then, after 1951 and until 2010, the name was used to include several other taxa that are now recognized as distinct species, including M. isthmica and M. simonsi. Therefore, late 20th-century publications about " " (e.g., O'Connell, 1983) may report observations that do not apply to, or that cannot be confidently attributed to, this species. (Rossi, et al., 2010)
Phylogenetic analyses of cytochrome-b sequence data suggest that (1) the sister taxon of M. xerophila; (2) that the sister taxon to + M. xerophila is a clade containing M. isthmica, M. mexicana, and M. zeledoni; and (3) that the sister taxon to these two clades is M. simonsi. Other species of Marmosa are yet more distantly related. (Gutierrez, et al., 2010)is
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.
uses sound to communicate
living in landscapes dominated by human agriculture.
Referring to an animal that lives in trees; tree-climbing.
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.
parental care is carried out by females
An animal that eats mainly insects or spiders.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
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.
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
scrub forests develop in areas that experience dry seasons.
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
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.
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.
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.
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.
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.
Alvizu, P., M. Aguilera. 1998. Uso del espacio de Marmosa robinsoni (Didelphidae: Marsupialia) en una zona xerofila de los Andes venezolanos. Ecotropicos, 11(2): 81-92.
Barnes, R., S. Barthold. 1969. Reproduction and breeding behavior in an experimental colony of Marmosa mitis Bangs (Didelphidae). Journal of reproduction and Fertility (supplement), 6: 477-482.
Barnes, R., H. Wolf. 1971. The husbandry of Marmosa mitis as a laboratory animal. International Zoo Yearbook, 11: 50-54.
Godfrey, G. 1975. A study of oestrus and fecundity in a laboratory colony of mouse opossums (Marmosa robinsoni). Journal of Zoology, 175: 541-555.
Gutierrez, E., S. Jansa, R. Voss. 2010. Molecular systematics of mouse opossums (Didelphidae: Marmosa): assessing species limits using mitochondrial DNA sequences, with comments on phylogenetic relationships and biogeography. American Museum Novitates, 3692: 1-22.
Lopez-Fuster, M., R. Perez-Hernandez, J. Ventura, M. Salazar. 2000. Effect of environment on skull-size variation in Marmosa robinsoni in Venezuela. Journal of Mammalogy, 81: 829-837.
O'Connell, M. 1979. Ecology of didelphid marsupials from northern Venezuela. Pp. 73-87 in J Eisenberg, ed. Vertebrate ecology in the northern Neotropics. Washington, DC: Smithsonian Institution Press.
O'Connell, M. 1983. Marmosa robinsoni. Mammalian Species, 203: 1-6.
Rossi, R., R. Voss, D. Lunde. 2010. A revision of the didelphid marsupial genus Marmosa. Part 1. The species in Tate's 'mexicana' and 'mitis' sections and other closely related forms. Bulletin of the American Museum of Natural History, 334: 1-81.
Tate, G. 1933. A systematic revision of the marsupial genus Marmosa. Bulletin of the American Museum of Natural History, 66: 1-250.