Geographic Range
Marmosa isthmica
occurs in the humid tropical lowlands of Panama, western Colombia, and western Ecuador
- Biogeographic Regions
- neotropical
Habitat
This species occurs in lowland and premontane rainforest, but field studies suggest
that it is much more abundant in secondary growth than in primary forest.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- rainforest
Physical Description
Like other species of
mouse opossums
,
Marmosa isthmica
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 reddish brown and the ventral fur is yellowish or orangish. Among other
diagnostic traits, this species differs from other species of
Marmosa
by lacking palatine fenestrae (always present in sympatric
M. robinsoni
); and by having small, laterally compressed, and ventrally pointed auditory bullae
(the bullae are larger, more rounded, and ventrally smooth in
M. robinsoni
). This species is sexually dimorphic (males are larger than females).
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Development
N/A
Reproduction
Breeding is seasonal in this species, but other aspects of the mating system are unknown.
This species is believed to breed once a year, probably in the late dry season (late
February and March, in central Panama). The litter size at birth is not known, but
the number of offspring attached to the teats of trapped females ranges from 6 to
12. Ovulation is probably spontaneous (as in other species of
Marmosa
).
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
As in other
opossums
, the young are highly altricial and attach themselves firmly to the mother's nipples
for some time after birth. No form of parental care other than female lactation has
been recorded.
- Parental Investment
- altricial
- female parental care
-
pre-fertilization
-
protecting
- female
-
protecting
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
provisioning
Lifespan/Longevity
Nothing is known about the longevity of this species in the wild or in captivity.
Behavior
Like other species of
Marmosa
,
M. isthmica
is arboreal/scansorial, nocturnal, nonmigratory, and solitary. Field observations
suggest that it prefers to climb on small-diameter substrates (narrow branches and
vines). Captive specimens are highly aggressive when competing for food with conspecifics
or other small mammals.
Home Range
Nothing is known about the home range of this species, but local populations appear
to fluctuate greatly in abundance from year to year, so spacing is probably highly
variable.
Communication and Perception
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. Males have sternal
glands that are presumably used for social scent-marking.
- Other Communication Modes
- scent marks
Food Habits
Observations of captive animals suggest that this species is largely insectivorous,
but it also eats fruit when available. Large insects (
grasshoppers
and
katydids
) are stalked, seized, and then killed by repeated bites to the head and thorax.
- Primary Diet
- carnivore
- Animal Foods
- insects
- Plant Foods
- fruit
Predation
Little is known about the natural predators of this species, but they probably include
snakes
,
owls
, and wild
felids
.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
This species is a primary consumer (of fruits) and a secondary consumer (of insects);
it is the prey of
owls
, and probably also of
snakes
and
carnivorans
; and it is the host of 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).
Economic Importance for Humans: Positive
It is doubtful that this species has any positive economic impact.
Economic Importance for Humans: Negative
There are no known adverse effects of Marmosa isthmica on humans.
Conservation Status
This species is widely distributed and can live in human-modified landscapes, so it
seems to be of no immediate conservation concern.
Other Comments
Between 1951 and 2010 this species was consistently misidentified as
Marmosa robinsoni
. Phylogenetic analyses of cytochrome-b sequence data, however, suggest that it is
most closely related to
M. zeledoni
and
M. mexicana
.
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.
- 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.
- 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.
- iteroparous
-
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).
- seasonal breeding
-
breeding is confined to a particular season
- 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.
- altricial
-
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.
- 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
- solitary
-
lives alone
- 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
Enders, R. 1935. Mammalian life histories from Barro Colorado Island, Panama. Bulletin of the Museum of Comparative Zoology , 78: 383-502.
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.
Park, O., A. Barden, E. Williams. 1940. Studies in nocturnal ecology, IX. Further analysis of activity of Panama rainforest animals. Ecology , 21: 122-134.
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.