Gardner & Creighton, 1989
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. It contains the following species:
- Aceramarca Gracile Opossum (Gracilinanus aceramarcae)
- Agile Gracile Opossum (Gracilinanus agilis)
- Wood Sprite Gracile Opossum (Gracilinanus dryas)
- Emilia's Gracile Opossum (Gracilinanus emilae)
- Northern Gracile Opossum (Gracilinanus marica)
- Brazilian Gracile Opossum (Gracilinanus microtarsus)
Gracile mouse opossums, excluding the fat-tailed mouse opossum, in general, have a prehensile tail that is thin and really long. The tails of mouse opossums are naked. Mouse opossums have ears that are, both, large and naked. General opossums, including Gracilinanus species, have noses that are pointed. Another general characteristic that mouse opossum have are mammary glands. Each member of the Gracilinanus species has a dark ring that is found around each eye. The species G. microtarsus has red-brown fur on the top of the body and gray fur on the underside. In comparison with G. microtarsus, G. agilis has paler fur color. Over the years, a new species, G. ignitus, has been added to the genus. G. ignitus has a white patch on its chest. It, as well, has a light, two-tone colored tail that has only a few hairs. The fur color can be used to determine if a member of the genus is part of the G. ignitus species. G. microtarsus, G. emiliae, and G. dryas can be distinguished from G. ignitus by their tails that are only one color. One difference between G. agilis and G. ignitus is that G. agilis has a hairier tail. G. aceramarcae has naked skin compared to G. ignitus. G. emiliae is smaller than G. ignitus. G. emiliae, in general, has a very long tail. A difference between G. emiliae and the rest of the species in the genus is that it has white fur on the underside of the body and the rest of the species have a gray or brown color.
Gracilinanus species can be found in a number of different places. The different regions that Gracilinanus species can be found are Peru, Bolivia, Brazil, Paraguay, and Venezuela. Some species are found in forests, trees, fallen trunks, tree holes, humid environments, and coffee plantations. G. emiliae is distributed along the Amazonia and the coast of Venezuelan rainforests. G. emiliae is one of the two species in the genus that is found in lowland Amazonian rainforests. G. agilis and G. microtarsus are the only two species that have been found in the central, south, and southeastern parts of Brazil. The other species have been found in the Amazon and not in Brazil. The production of sugar cane and fruits, along with deforestation, is thought to be a reason why the newer specie, G. ignitus, has been harder to find.
Out of the species that currently exist, only two of them have made it on to the endangerment list. Gracilinanus agilis is not considered to be threatened, in general, but in the specific area of Paraguay, the species is close to being threatened. The only other species that is near threatened is G. dryas. A major threat to these species is that their main habitat is being destroyed by deforestation. However, it has also been reported that these species are on the critically endangered list because they are only known in two general areas where their habitat has been found to be taking a decline. The species of the genus Gracilinanus once occupied regions in South America and Europe, but are now extinct there.
The specific species G. microtarsus has a diet that includes insects, spiders, fruits, termites, beetles and ants. As well, this species has been known to live off of wasps and small invertebrates. However, the main component of G. microtarsus’ diet is ants. It is reported that the male species eat more food than the females.
Different from the usual, the female has two vaginas and the males have a two-pronged penis. Some females can have a litter size of up to 15, but usually have a litter of about 7. Females of the species do not have a pouch that the young are able to stay in. For those that do not have a pouch, the young are only attached to the nipples for a short time period and are left in their nests early on in their life.
Some species are nocturnal. A few Gracilinanus species know how to play dead. The newest specie that was found, G. ignitus, is reported to be one of the largest of all the species. G. emiliae is one of the species that has only a dozen specimens found. The species in this genus are known to climb a lot and dig holes in trees or the ground.
- Gardner, A. L. (2005). "Order Didelphimorphia". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 6–7. ISBN 978-0-8018-8221-0. OCLC 62265494.
- "Mouse opossum". Encyclopedia Britannica. Encyclopedia Britannica Online Academic Edition. Encyclopedia Britannica Inc., 2012. Web 3 November 2012. <http://www.britannica.com/EBchecked/topic/395096/mouse-opossum>
- "Opossum." - New World Encyclopedia. N.p., 18 Sept. 2008. Web. 3 November 2012. <http://www.newworldencyclopedia.org/entry/Opossum>.
- "Mammals." EDGE of Existence. Web. 28 November 2012. <http://www.edgeofexistence.org/mammals/species_info.php?id=35>.
- Pires, Mathias M., Eduardo G. Martins, Maria Nazareth F. Silva, and Sérgio F. Dos Reis. "Gracilinanus Microtarsus (Didelphimorphia: Didelphidae)." Mammalian Species 42 (2010).
- Díaz, M. Mónica, David A. Flores, and Rubén M. Barquez. "A New Species Of Gracile Mouse Opossum, Genus Gracilinanus (Didelphimorphia: Didelphidae), From Argentina." Journal of Mammalogy 83.3 (2002).
- Voss, R. S., D. W. Fleck, and S. A. Jansa. "On the Diagnostic Characters, Ecogeographic Distribution, and Phylogenetic Relationships of Gracilinanus Emiliae (Didelphimorphia: Didelphidae: Thylamyini)." Mastozoologia Neotropical 16.2 (2009): 434,36. <http://redalyc.uaemex.mx/redalyc/pdf/457/45712497015.pdf>
- Patterson, B. & Solari S. 2008. Gracilinanus aceramarcae. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <http://www.iucnredlist.org/details/9416/0>. Downloaded on 3 November 2012.
- Carmignotto, A., Solari, S., de la Sancha, N. & Costa, L. 2011. Gracilinanus agilis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <http://www.iucnredlist.org/details/9417/0>. Downloaded on 3 November 2012.
- Brito, D., Astua de Moraes, D., Lew, D., Soriano, P. & Emmons, L. 2008. Gracilinanus emiliae. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <http://www.iucnredlist.org/details/9419/0>. Downloaded on 3 November 2012.
- Pérez-Hernandez, R., Lew, D., Gutiérrez, E. & Ventura, J. 2011. Gracilinanus dryas. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <http://www.iucnredlist.org/details/9418/0>. Downloaded on 3 November 2012.
- Lew, D., Pérez-Hernandez, R., Ventura, J., Gutiérrez, E. & López Fuster, M. 2011. Gracilinanus marica. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <http://www.iucnredlist.org/details/9420/0>. Downloaded on 3 November 2012.
- Brito, D., Astua de Moraes, D., Lew, D. & Soriano, P. 2008. Gracilinanus microtarsus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <http://www.iucnredlist.org/details/9421/0>. Downloaded on 3 November 2012.
- Geise, Lena, and Diego Astúa. "Distribution Extension and Sympatric Occurrence of Gracilinanus agilis and G. Microtarsus (Didelphimorphia, Didelphidae), with Cytogenetic Notes." BAR. Brazilian Administration Review 9.4 (2009). <http://www.scielo.br/scielo.php?pid=S1676-06032009000400030&script=sci_arttext>
- Martins, E. G., V. Bonato, H. P. Pinheiro, and S. F. Dos Reis. "Diet of the Gracile Mouse Opossum (Gracilinanus Microtarsus) (Didelphimorphia: Didelphidae) in a Brazilian Cerrado: Patterns of Food Consumption and Intrapopulation Variation." Journal of Zoology 269.1 (2006). <http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.2006.00052.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false>
- . Martins, E. G., and V. Bonato. "On the Diet of Gracilinanus Microtarsus (Marsupialia, Didelphidae) in an Atlantic Rainforest Fragment in Southeastern Brazil." Mammalian Biology 69 (2004): 58-59. Print.