The buff-bellied fat-tailed mouse opossum (''Thylamys venustus'') is a species of

opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 126 species in 18 genera. Opossums originated in South America and entered North A ...

in the family Didelphidae. It is found in the transitional and humid forests of northern Argentina and southern

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

. Its

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

fur is cinnamon brown. Most of its

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

fur is gray-based, but its chest, throat, and the thoracic midline (the midline of the

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

, which ranges from the throat to the top of the abdomen) are not gray-based. The postorbital ridges are absent in the young and weakly developed in adults. Initially classed as a Marmosa elegans

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

, it was subsequently raised to species status in 1933. There are four

synonyms A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

: ''Marmosa elegans venusta'' (Thomas, 1902,

Cochabamba Cochabamba (; ) is a city and municipality in central Bolivia in a valley in the Andes mountain range. It is the capital (political), capital of the Cochabamba Department and the list of cities in Bolivia, fourth largest city in Bolivia, with ...

), ''Marmosa elegans cinderella'' (Thomas, 1902,

Tucumán Province Tucumán () is the most densely populated, and the second-smallest by land area, of the provinces of Argentina. Located in the northwest of the country, the province has the capital of San Miguel de Tucumán, often shortened to Tucumán. Neighb ...

), ''Marmosa elegans sponsoria'' (Thomas, 1921,

Jujuy Province Jujuy is a province of Argentina, located in the extreme northwest of the country, at the borders with Chile and Bolivia. The only neighboring Argentine province is Salta to the east and south. Geography There are three main areas in Jujuy ...

) and ''Marmosa janetta'' (Thomas, 1926, Tarija Department) with ''cinderella'' and ''sponsoria'' actually being one

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

and a

of ''venustus''; ''janetta'' is the largest of all and has cream-white ventral fur with plumbeous bases. Its

conservation status The conservation status of a group of organisms (for instance, a species) indicates whether the group still exists and how likely the group is to become extinct in the near future. Many factors are taken into account when assessing conservation ...

is not exactly known; it occurs in an area currently being developed, and while its range overlaps several protected areas, it is uncertain if it occurs in any of them.

References

Further reading