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 America in the Great American Interchange following the connection of North and South America.
The woolly mouse opossum or long-furred woolly mouse opossum, known locally as the cuíca, is a South American marsupial of the family Didelphidae. Its range includes central Colombia, Venezuela, French Guiana, Guyana, Suriname, eastern Peru, northern Bolivia, and northern Brazil. It was formerly assigned to the genus Micoureus, which was made a subgenus of Marmosa in 2009.
The 27 species in the genus Marmosa are relatively small Neotropical members of the family Didelphidae. This genus is one of three that are known as mouse opossums. The others are Thylamys and Tlacuatzin, the grayish mouse opossum. Members of the genus Marmosops used to be called "slender mouse opossums", but are now just called "slender opossums". The thirteen members of the Marmosa subgenus Micoureus, known as woolly mouse opossums, were formerly considered to be a separate genus, but were moved into Marmosa in 2009. Based on a comparison of sequences of one mitochondrial and three nuclear genes, three new subgenera, Eomarmosa, Exulomarmosa and Stegomarmosa, were recognized by Voss et al. in 2014. Eomarmosa and Exulomarmosa, as well as Marmosa and Micoureus, are thought to be sister taxa, while Stegomarmosa is viewed as sister to Marmosa plus Micoureus. Exulomarmosa is a mostly trans-Andean clade.
The Patagonian opossum(Lestodelphys halli) is the sole species in genus Lestodelphys.
Marmosops is a genus of Neotropical opossums of the family Didelphidae. The genus was originally treated as a subgenus from the genus Marmosa rather than having their own classification. This was changed in 1989 by Gardner and Crieghton, who officially separated the group and made them their own genus. The mix-up between to genera Marmosa and Marmosops was common due to the similar appearances including size and other external features. However, the two groups differ significantly in their integument and in the arrangement of their skull and dentition. The dentition is similar in morphology between the two groups, with the exception of the deciduous lower third premolar varying from one genus to the next. The similarity between the two continues to cause the genus Marmosops to be frequently misidentified due to the lack of knowledge regarding the species along with the overlooked traits that help separate them from other opossums. The Marmosops are also commonly confused with the genus Gracilinanus, but this is quickly ruled out by a large number of differing characteristics. These differences include the arrangement of their digits, caudal scales, and the central hair on the scales changing from a three hairs per follicle to many more. This causes the hair of the Gracilinanus to be thicker and has also found to be heavily pigmented. The last group commonly confused with Marmosops is known as the genus Thylamys. These animals have a contrasting dorsal body pelage and the taxa are actually quite different.
The Mexican mouse opossum is a species of North American opossum in the family Didelphidae.
Thylamys is a genus of opossums in the family Didelphidae. The premaxillae are rounded rather than pointed. The females lack a pouch. The females' nipples are arranged in two symmetrical rows on the abdomen. All species but T. macrurus store fat in their tails., although this is not necessarily true for all species in the genus. Fossils belonging to the genus date back to the Miocene, with the oldest specimens being found in the Cerro Azul Formation of Argentina and the Honda Group of Colombia. Genetic studies indicate that the genus may have originated around 14 million years ago.
The white-bellied fat-tailed mouse opossum is a species of opossum in the family Didelphidae. It is found in Argentina, Bolivia, Chile and Peru.
Gracilinanus is a genus of opossum in the family Didelphidae. It was separated from the genus Marmosa in 1989, and has since had the genera Cryptonanus, Chacodelphys, and Hyladelphys removed from it.
The Didelphinae are a subfamily of opossums consisting of 15 genera and 123 species. Specimens have been collected throughout the Americas, but are predominant in South and Central America.
Bishop's slender opossum is a small, arboreal marsupial opossum native to Brazil, Peru, and Bolivia. It somewhat resembles a placental rat or shrew.
The buff-bellied fat-tailed mouse opossum is a species of opossum in the family Didelphidae. It is found in the transitional and humid forests of northern Argentina and southern Bolivia. Its dorsal fur is cinnamon brown. Most of its ventral fur is gray-based, but its chest, throat, and the thoracic midline are not gray-based. The postorbital ridges are absent in the young and weakly developed in adults.
The chacoan gracile opossum is a species of opossum in the family Didelphidae. It is native to Argentina, Brazil and Paraguay. Its habitat is seasonally flooded grasslands and forests in and near the Gran Chaco.
The Guahiba gracile opossum is a species of opossum in the family Didelphidae. It is endemic to southern Brazil, where it is known only from three islands, Guahiba, São Lourenço, and Taquara, in the state of Rio Grande do Sul. The poorly studied species is presumed to inhabit subtropical forests, and thus to be threatened by deforestation.
The Unduavi gracile opossum is a species of opossum in the family Didelphidae. It is native to northern Bolivia, where it has been found in seasonally flooded grassland. Some of the specimens recognized by Voss et al. as belonging to this species were previously classified as the unduaviensis or buenavistae subspecies of Gracilinanus agilis.
Tate's woolly mouse opossum is an omnivorous, arboreal South American marsupial of the family Didelphidae, named after American zoologist George Henry Hamilton Tate. It is native to Atlantic coastal forests of Brazil, Paraguay and Argentina. The species lives in both primary and secondary forest, including forest fragments within grassland. Insects are a major component of its diet. It was formerly assigned to the genus Micoureus, which was made a subgenus of Marmosa in 2009. While its conservation status is "least concern", its habitat is shrinking through urbanization and conversion to agriculture over much of its range.
Cryptonanus is a genus of opossums from South America. It includes five species found from Bolivia to Uruguay and eastern Brazil, one of which is now extinct. Although the first species were discovered in 1931, the genus was not recognized as distinct from Gracilinanus until 2005. It includes small opossums with generally grayish, sometimes reddish, fur that are mainly distinguished from other opossums by characters of the skull.
