The elegant fat-tailed mouse opossum (''Thylamys elegans''), also known as the Chilean mouse opossum, is an

opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...

from central

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

of '' Thylamys'', it was first described by English naturalist

George Robert Waterhouse George Robert Waterhouse (6 March 1810 – 21 January 1888) was an English naturalist. He was a keeper at the department of geology and later curator of the Zoological Society of London's museum. Early life George was born in Somers Town t ...

in 1839. This medium-sized opossum is characterized by black rings around the eyes, white limbs, gray to light brown coat, lighter flanks and underbelly and a thick long tail covered with hairs. It is

crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylig ...

(active mainly around twilight) and lives in nests in tree hollows or under rocks and roots. This opossum feeds mainly on

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, o ...

s and larvae apart from fruits. Litter size is typically between 11 and 13. The elegant fat-tailed opossum can occur in a variety of habitats – from

cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest (TMCF), is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level clou ...

s to

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean ...

s. The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

classifies the opossum as

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

Taxonomy and etymology

The elegant fat-tailed mouse opossum is the

of '' Thylamys'', and is placed in the family Didelphidae. It was first described by English naturalist

as ''Didelphis elegans'' in 1839. It was given its present binomial name by English zoologist

John Edward Gray John Edward Gray, FRS (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for ...

in 1843. The

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

below, based on a 2016 study, shows the

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relationships of the elegant fat-tailed mouse opossum. The generic name is composed of the Greek words ''thylas'' ("pouch") and ''mys'' ("mouse"), and the specific name ''elegans'' means "elegant" in Latin. Alternate names for this mouse opossum include Chilean mouse opossum, comadreja, llaca, marmosa chilena, marmosa elegante and yaca.

Description

The elegant fat-tailed mouse opossum is a medium-sized

characterized by white limbs, gray to light brown coat, lighter flanks and underbelly, and a thick long tail covered with hairs. A prominent facial feature is the black ring around either eye; the rings slightly extend toward the nose. The coat color varies geographically. The tail can thicken due to accumulation of fat; the diameter of the tail can reach where it is connected to the body. The head-and-body length is ; the hindfeet measure , while ears measure . This opossum can exhibit

torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...

, a mechanism that allows the opossum to significantly reduce its food and energy requirements. This is similar to

hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...

, except that it is only done for a short period of time. Additionally, when water is scarce, the urine tends to become very concentrated.

Ecology and behavior

The elegant fat-tailed mouse opossum is

(active mainly around twilight). It lives in nests (abandoned by birds and rodents, or built by itself) in tree hollows, under rocks and roots. It is

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...

(tree-living) as well as

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

(land-living). The opossum feeds mainly on

s and larvae, along with fruits, small

vertebrate Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...

s and carrion. This opossum can use its

prehensile tail A prehensile tail is the tail of an animal that has adapted to grasp or hold objects. Fully prehensile tails can be used to hold and manipulate objects, and in particular to aid arboreal creatures in finding and eating food in the trees. If the ta ...

, regardless of its thickness, to efficiently climb and grasp branches – an ability not as developed in other small Chilean mammals. Nests are generally occupied by one individual; in southern Chile, the

home range A home range is the area in which an animal lives and moves on a periodic basis. It is related to the concept of an animal's territory which is the area that is actively defended. The concept of a home range was introduced by W. H. Burt in 1943. He ...

of this opossum is large in July, and shrinks to in December. Predators of this opossum include the culpeo fox,

burrowing owl The burrowing owl (''Athene cunicularia''), also called the shoco, is a small, long-legged owl found throughout open landscapes of North and South America. Burrowing owls can be found in grasslands, rangelands, agricultural areas, deserts, or any ...

and the

great horned owl The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air"), or the hoot owl, is a large owl native to the Americas. It is an extre ...

. Both sexes mature by the first year. A female can have one to two litters in the annual breeding season, typically from September to March. Up to 17 embryos can be produced, but the number of survivors will depend on the number of nipples functioning (typically 11 to 13).

Distribution and status

The elegant fat-tailed mouse opossum occurs in a variety of habitats – from

s to

s, up to an altitude of above the sea level. It occurs to the west of the Andes in central Chile. The

lists this opossum as

given its wide distribution and presumably large numbers, but

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...

and

agricultural expansion Agricultural expansion describes the growth of agricultural land (arable land, pastures, etc.) especially in the 20th and 21st centuries. The agricultural expansion is often explained as a direct consequence of the global increase in food and ener ...

have led to decline in populations in some parts of the range.

References

External links

* {{Taxonbar, from=Q194410 Opossums Marsupials of South America Mammals of Patagonia Mammals of the Andes Mammals of Argentina Mammals of Chile Taxa named by George Robert Waterhouse Mammals described in 1839 Taxonomy articles created by Polbot Endemic fauna of Chile