The Isthmian Mouse Opossum (Marmosa isthmica) is a species of opossum in the family Didelphidae found in Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

 and Panama

Panama

Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

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Foraging along branches and vines for fruit and insects, with the help of a prehensile tail

Prehensile tail

A prehensile tail is the tail of an animal that has adapted to be able to grasp and/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...

, M. isthmica was formerly considered a subspecies of Robinson's Mouse Opossum

Robinson's Mouse Opossum

Robinson's Mouse Opossum is a species of opossum in the Didelphidae family.It is found in Belize, Colombia, Ecuador, Grenada, Honduras, Panama, Peru, Trinidad and Tobago, and Venezuela....

 (Marmosa robinsoni) and is supposed to be similar to it in habit, but following Rossi (2005) it is now deemed a species.

In 1935 in the Panama Canal Zone

Panama Canal Zone

The Panama Canal Zone was a unorganized U.S. territory located within the Republic of Panama, consisting of the Panama Canal and an area generally extending 5 miles on each side of the centerline, but excluding Panama City and Colón, which otherwise would have been partly within the limits of...

, Enders observed Marmosa isthmica to build nests with leaves in a nestbox fixed to a tree.