Gracilinanus marica (northern gracile mouse opossum) | INFORMATION

Scientific Classification

Rank	Scientific Name
Kingdom	Animalia animals
Phylum	Chordata chordates
Subphylum	Vertebrata vertebrates
Class	Mammalia mammals
Order	Didelphimorphia American marsupials
Family	Didelphidae American opossums and opossums
Genus	Gracilinanus gracile mouse opossums
Species	Gracilinanus marica northern gracile mouse opossum

By Leila Siciliano Martina

Geographic Range

Northern gracile opossums ( Gracilinanus marica ) are found in northern South American in Venezuela, Columbia and Trinidad. These animals have been reported in the Cordillera de la Costa and Cordillera de Merida in Venezuela and Sierra de Perija, Departmento la Guajira and la Selva in Columbia.

Biogeographic Regions
neotropical
- native

Habitat

Northern gracile opossums are found in pre-montane to montane environments of the Andes Mountains. They are found in a variety of habitats, including humid evergreen, deciduous and cloud forests, as well as savannahs and rainforests, from near sea level up to 4,000 m. This species has also been reported residing in coffee plantations.

Habitat Regions
tropical

Other Habitat Features
agricultural

Physical Description

Northern gracile opossums are small, pouchless marsupials with mottled, reddish-brown dorsal pelage and buff ventral pelage. These animals are adapted for an arboreal lifestyle, as shown by their long tail. Their total body length is about 230 mm, including a tail length of about 130 mm; in general, their tail-to-body ratio is 1.3. Their hind feet are about 16.5 mm long. Northern gracile opossums are occasionally mistaken for their relative, wood-sprite opossums ( Gracilinanus dryas ); however, wood-sprite opossums have longer, darker fur with striking, light colored guard hairs, giving them a frosted appearance. Members of genus Gracilinanus are sexually dimorphic, where males are larger than females. Members of this genus may grow lifelong, these species are short-lived; however, the rare individuals that survive multiple years tend to be noticeably larger. In general, the temperature and metabolic rate of didelphids tends to be lower than similarly sized placental mammals.

Other Physical Features
endothermic
bilateral symmetry

Sexual Dimorphism
male larger

Reproduction

Didelphids engage in a polygynous mating system. There is very little information specific to northern gracile opossums; however, the extreme competition among males for breeding females may cause a massive amount of stress. Other members of genus Gracilinanus are considered partially semelparous because many of the males die shortly after breeding. This trend is considered only partial because a few males do survive to a second or even third breeding season.

Mating System
polygynous

There is very little information specifically regarding the reproductive behavior of northern gracile opossums. Much more research has been conducted on their close relative, Brazilian gracile opossums . It is not known whether these species share all reproductive traits, however, it is not unlikely that these species share at least some reproductive traits. Brazilian gracile opossums begin mating when they are about 1 year old. This species reproduces seasonally; females are receptive during the end of the cool dry season, from August to September. Several pregnant and lactating females have been captured in September to December. Brazilian gracile opossums’ strategy of synchronous estrous means that their young are born in October to December, during the first half of the warm wet season when insect prey are most populous. This likely optimizes the female’s ability to capture food while caring for young. Litters are composed of 6 to 14 individuals, with an average of 11 offspring. Weaning begins at about 2 to 3 months of age, when the young weigh about 8 to 10 grams.

Key Reproductive Features
seasonal breeding
gonochoric/gonochoristic/dioecious (sexes separate)
sexual
viviparous

Genus Gracilinanus is composed are pouchless marsupials. Both attached and unattached young usually stay near their mother; however, older offspring may stay behind in the nest while their mother forages. Brazilian gracile opossums , a close relative of northern gracile opossums, wean their offspring when they are about 2 to 3 months old, during the warm wet season.

Parental Investment
female parental care

Lifespan/Longevity

There is currently no information regarding the lifespan of northern gracile opossums specifically, however, other members of genus Gracilinanus typically live 1 to 2 years. Likewise, other members of this genus are considered partially semelparous; most males do not survive to a second breeding season. Among Brazilian gracile opossums , a close relative of northern gracile opossums, males invest so much in competing for mates that they often show fur loss, poor body condition and are more likely to become infested with parasites after the beginning of the breeding season. Although females also have a short lifespan, they survive to a second year more frequently than males. In general, offspring from the preceding season replace the adults each year.

Behavior

Members of genus Gracilinanus are solitary and nocturnal; they typically only come together for breeding. They may forage in a similar location, but do not interact. These animals are mostly arboreal, but may forage on the ground. Other members of their genus are known to enter torpor when the temperature is colder than 20°C.

Key Behaviors
arboreal
nocturnal
motile
solitary

Home Range

There is currently no information regarding the home range size of northern gracile opossums. However, their close relative, Brazilian gracile opossums have home range sizes of approximately 1,400 meters squared for males and 1,200 meters squared for females.

Communication and Perception

There is very little information regarding the communication or perception of genus Gracilinanus . Members of this genus may produce a variety of sounds defensively or when they are startled, these sounds include hissing, growling and screeching. It has been suggested that arboreal marsupials are more vocal and have more adept vision than their non-arboreal counterparts; however, no conclusive studies have been conducted.

Communication Channels
visual
acoustic

Perception Channels
visual
tactile
acoustic
chemical

Food Habits

Very little is known about the feeding habits of northern gracile opossums. Other members of genus Gracilinanus are insectivorous, consuming primarily beetles , ants and wasps . In addition, other members of the genus also eat fruits, especially during the dry season and are important seed dispersers. Although these species are arboreal, most forage on the ground.

Primary Diet
carnivore
- insectivore

Animal Foods
insects

Plant Foods
fruit

Predation

There is currently no information regarding the predation of northern gracile opossum specifically, however, general predators of genus Gracilinanus may include various owls , snakes and lizards . Similar species are predated upon by white-tailed hawks , crab-eating foxes , oncillas , maned wolves , margays and jaguarundis . Likewise, the remains of unidentified members of genus Gracilinanus have also been recorded in the scat of ocelots , coatis and striped owls .

Ecosystem Roles

Northern gracile opossums are likely insectivores and seed dispersers. Other members of genus Gracilinanus are known to host a variety of nematodes , lice and botfly larvae.

Economic Importance for Humans: Positive

There are currently no known positive impacts of northern gracile opossums on human populations.

Economic Importance for Humans: Negative

Although northern gracile opossums have been reported in coffee plantations, there have been no known reports of damage.

Negative Impacts
crop pest

Conservation Status

Northern gracile opossums are considered a species of least concern according to the IUCN Red List of Threatened Species. This species likely has a fairly large population and can survive in human-altered environments.

Additional Links

Encyclopedia of Life

Contributors

Leila Siciliano Martina (author), Texas State University.

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

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.

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.

forest: forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

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.

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.

polygynous: having more than one female as a mate at one time

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.

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.

solitary: lives alone

visual: uses sight to communicate

acoustic: uses sound to communicate

visual: uses sight to communicate

tactile: uses touch to communicate

acoustic: uses sound to communicate

chemical: uses smells or other chemicals to communicate

carnivore: an animal that mainly eats meat

insectivore: An animal that eats mainly insects or spiders.

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.

References

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