Geographic Range
This lowland species is distributed in south-eastern Bolivia, western Paraguay, and
north-eastern and central Argentina.
- Biogeographic Regions
- neotropical
Habitat
Thylamys pusillus
inhabits the arid and semi-arid lowlands of central South America, including the
Chaco, Monte, and Pampas ecoregions.
- Habitat Regions
- tropical
- Terrestrial Biomes
- desert or dune
- savanna or grassland
Physical Description
Like other members of its genus,
Thylamys pusillus
is notable for its incrassate (fattened) tail. The size of the tail varies by season
in accordance with food availability. Although this species is a marsupial, females
do not have a pouch. This species is tricolored, with darker dorsal fur, paler lateral
fur, and a white ventral region. This species is broadly similar morphologically to
Thylamys macrurus
but much smaller. It is also quite similar to
Thylamys pallidior
, a species that occurs in some of the same areas as
Thylamys pusillus
. Dorsal hair length and ventral hair color are useful characters for differentiating
between these two species (Giarla et al., 2010). Giarla et al. (2010) report head
and body lengths that range from 88 to 116 mm (average 98 mm) and tail lengths that
range from 98 to 134 mm long (average 109 mm).
- Other Physical Features
- endothermic
- bilateral symmetry
Reproduction
No published studies have examined mating systems in Thylamys pusillus .
Little is known about the general reproductive behavior of Thylamys pusillus .
- Key Reproductive Features
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Little is known about parental investment in
Thylamys pusillus
. Like all marsupials, females nurse their highly altricial young. However, because
members of the genus
Thylamys
lack a pouch (marsupium), the young must cling to their mother's venter.
- Parental Investment
- altricial
- female parental care
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
No records of this species' lifespan are available.
Behavior
Little is known about the behavior of
Thylamys pusillus
. This species is likely solitary, as most small, insectivorous mammals are. As is
the case for other members of this genus,
Thylamys pusillus
is likely nocturnal and probably enters torpor during the day.
Home Range
No studies have examined the home range of Thylamys pusillus .
Communication and Perception
Because this species is small and nocturnal, communication between individuals is
likely primarily olfactory in nature. Palma (1997) reports that the olfactory and
visual regions of another
Thylamys
species' brain are especially well developed.
- Perception Channels
- visual
- tactile
- acoustic
- vibrations
- chemical
Food Habits
Little is known about the food habits of this species. Like other
Thylamys
species,
Thylamys pusillus
likely consumes insects and perhaps occasionally eats small vertebrates, leaves,
fruit, seeds, and carrion (Palma 1997).
- Primary Diet
- carnivore
Predation
Like other small mammals,
Thylamys pusillus
is likely well adapted to avoiding predators by being nocturnal and inconspicuous.
No records of known predators are available.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
Thylamys pusillus
likely acts as an important predator to many arthropod species and perhaps some small
vertebrates. It is likely prey to both bird and medium-sized mammals, such as owls
and foxes. It is also likely host to many ecto- and endoparasites. More specific information
about the ecosystem role of
Thylamys pusillus
is not presently available.
Economic Importance for Humans: Positive
There are no known positive impacts of Thylamys pusillus on humans.
Economic Importance for Humans: Negative
There are no known negative effects of Thylamys pusillus .
Conservation Status
This species is listed as "Least Concern" by the IUCN.
Additional Links
Contributors
Tom Giarla (author), University of Minnesota, Sharon Jansa (editor), American Museum of Natural History, Robert Voss (editor), American Museum of Natural History, Tanya Dewey (editor), University of Michigan-Ann Arbor.
- 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.
- desert or dunes
-
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- 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.
- 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.
- solitary
-
lives alone
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- 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.
- 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
Giarla, T., R. Voss, S. Jansa. 2010. Species Limits and Phylogenetic Relationships in the Didelphid Marsupial Genus Thylamys Based on Mitochondrial DNA Sequences and Morphology. Bulletin of the American Museum of Natural History , 346: 1-67.
Palma, R. 1997. Thylamys elegans. Mammalian Species , 572: 1-4.
Voss, R., P. Myers, F. Catzeflis, A. Carmignotto, J. Barreiro. 2009. The Six Opossums of Felix de Azara: Identification, Taxonomic History, Neotype Designations, and Nomenclatural Recommendations. Bulletin of the American Museum of Natural History , 331: 406-433.