Geographic Range
Marmosa robinsoni
occurs in Panama, Colombia, northern Venezuela, adjacent continental-shelf islands
(Isla Margarita, Trinidad, Tobago), and Grenada.
- Biogeographic Regions
- neotropical
Habitat
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.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- rainforest
- scrub forest
- mountains
- Other Habitat Features
- agricultural
Physical Description
Like other species of
mouse opossums
,
Marmosa robinsoni
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).
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
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 robinsoni
were actually based on studies of other species (e.g.,
Marmosa isthmica
).
Marmosa robinsoni
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
M. xerophila
) are known to be seasonal breeders, and
M. robinsoni
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.
- Key Reproductive Features
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Females nurse the young for several weeks and presumably groom them and protect them
from predators at the same time.
- Parental Investment
- female parental care
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
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.
Behavior
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.
Home Range
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.
Communication and Perception
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.
- Other Communication Modes
- scent marks
Food Habits
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 robinsoni
, like that of other
Marmosa
species, is consistent with a mainly insectivorous diet.
- Primary Diet
- carnivore
- Animal Foods
- insects
- Plant Foods
- fruit
Predation
Nothing seems to be known about the natural predators of this species, but they probably
include
snakes
,
owls
, and wild
felids
.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
Marmosa robinsoni is probably a primary consumer (of fruit) and a secondary consumer (of 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).
Economic Importance for Humans: Positive
This species is not known to be of any positive economic importance for humans.
Economic Importance for Humans: Negative
There are no known adverse effects of Marmosa robinsoni on humans.
Conservation Status
Marmosa robinsoni
is geographically widespread and thrives in many kinds of human-modified landscapes.
Other Comments
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
M. robinsoni
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 "
Marmosa robinsoni
" (e.g., O'Connell, 1983) may report observations that do not apply to, or that cannot
be confidently attributed to, this species.
Phylogenetic analyses of cytochrome-b sequence data suggest that (1) the sister taxon
of
Marmosa robinsoni
is
M. xerophila
; (2) that the sister taxon to
M. robinsoni
+
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.
Additional Links
Contributors
Robert Voss (author), American Museum of Natural History, Sharon Jansa (editor), American Museum of Natural History, Alexa Unruh (editor), Animal Diversity Web Staff.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- 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.
- rainforest
-
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.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- mountains
-
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- agricultural
-
living in landscapes dominated by human agriculture.
- 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.
- 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.
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- female parental care
-
parental care is carried out by females
- arboreal
-
Referring to an animal that lives in trees; tree-climbing.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- 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.
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
References
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. 1983. Marmosa robinsoni . Mammalian Species , 203: 1-6.
O'Connell, M. 1979. Ecology of didelphid marsupials from northern Venezuela. Pp. 73-87 in Vertebrate ecology in the northern Neotropics . Washington, DC: Smithsonian Institution Press.
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.