''Marmosops'' is a genus of

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

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 ...

s 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 In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, Exoskeleton, shell, germ or Peel (fruit), rind. Etymology The term is derived from ''integumentum'', which is Latin for "a coverin ...

and in the arrangement of their skull and

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

.
Voss, R.S., Tarifa, T., and E. Yensen. 2004. An Introduction to Marmosops (Marsupialia: Didelphidae), with the Description of a New Species from Bolivia and Notes on the Taxonomy and Distribution of Other Bolivian Forms. American Museum of Natural History. 3466:2-34. The dentition is similar in morphology between the two groups, with the exception of the

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

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 (anatomical term) 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 provi ...

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 A fur is a soft, thick growth of hair that covers the skin of almost all mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an ...

and the taxa are actually quite different.

Taxonomy

Mammal Species of the World ''Mammal Species of the World: A Taxonomic and Geographic Reference'' is a standard reference work in mammalogy giving descriptions and Bibliographic database, bibliographic data for the known species of mammals. It is now in its third edition, ...

, but not by the

American Society of Mammalogists The American Society of Mammalogists (ASM) was founded in 1919. Its primary purpose is to encourage the study of mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence ...

: * Narrow-headed slender opossum ('' M. cracens'')

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

, synonymized with ''M. fuscatus'' * Dorothy's slender opossum ('' M. dorothea'') synonym of ''M. noctivagus'' * Tschudi's slender opossum ('' M. impavidus'') synonym of ''M. caucae'' * Neblina slender opossum ('' M. neblina'') synonym of ''M. caucae''

General traits

The ''Marmosops'' tend to be nocturnal, small marsupials and have been found to live on the ground. Many females of the ''M. paulensis'' species are known to be extremely territorial with a strong defense of their food, especially while in the presence of their young.Leiner, N.O. and W.R. Silva. 2009. Territoriality in females of the slender opossum (Marmosops paulensis) in the Atlantic forest of Brazil. Journal of Tropic Ecology. 25:671-675. The genus ''Marmosops'' is frequently misidentified and lumped into groups containing other species.Diaz-N, J.F. 2012. New Records of Marmosops noctivagus (Tschudi, 1845) (Didelphimorpia: Didelphidae) and first record of Marmosops bishop (Pine, 1981) for Colombia. Check List: Journal of Species lists and Distribution. 8:805-809. As of today, ''Marmosops'' are currently recognized as a distinct taxon with 36 taxa: 14 valid species and 22 subspecies. The species within the genus differ slightly, but not enough to be classified as separate genera. Some of the species are also nicknamed by appearance, with the ''M. paulensis'' known as the slender opossum, the ''M. noctivagus'' recognized as the largest species and the ''M. bishopi'' the smallest of the genus.Hice, C.L. 2003. The non-volant mammals of the estacion biologica allpahuayo: Assessment of the natural history and community ecology of a proposed reserve. Texas Tech University. 69-75.

Habitat

The main habitat for the ''Marmosops'' is found between the Neotropical humid forests ranging from

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

to the South of

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

and sometimes in Bolivia as well. The ''Marmosops'' prefer to live on the grounds of forests, staying away from high branches of trees. They often hide in the dense understory with high plant coverage surrounding them. They are highly influenced by rain and predation, with migration occurring more often during certain seasons. The genus is never found to live up in a

canopy (biology) In biology, the canopy is the aboveground portion of a plant community, plant cropping or crop, formed by the collection of individual Crown (botany), plant crowns. In forest ecology, the canopy is the upper layer or habitat zone, formed b ...

or in the trees, but instead typically prefer more accessible habitats where it is easier to hide. There is not much known regarding the

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

of the genus due to their migration patterns and unique preferences.

Diet

The diet of ''Marmosops'' includes, but is not limited to fruit,

arthropods Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

, flowers and small vertebrates.Leiner, N.O. and W.R. Silva. 2007. Effects of resource availability on the use of space by the mouse opossum Marmosops paulensis (Didelphidae) in a montane Atlantic forest area in southeastern Brazil. Acta Theriologica. 52:197-204 They also will eat insects,

arachnids Arachnids are arthropods in the class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroons. Adult arachnids ...

, and gastropods depending on the species and time of the year. Their diet seems to change with the seasons, with more diversity in food preference shown in the drier seasons. Each species has a slightly different diet depending on their habitat and what is available in that area.

Reproduction

Most of the ''Marmosops'' carry their offspring

in utero The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic and fetal development of one or more fertilized eggs until bir ...

and feed them through the process of lactation. There is a high reproduction rate in the months of September through March for ''M. paulensis'', with more mating occurring when there is a larger food supply. For this species, death occurred after every mating event was completed. This ensured that there was no more than one mating event for each animal that reproduced.N.O. Leiner, E.Z.F. Setz, and W.R. Silva. 2008. Semelparity and factors affecting the reproductive activity of the Brazilian slender opossum (Marmosops paulensis) in southeastern Brazil. Journal of Mammalogy. 89:153-158. Successful breeding depends on the presence of females, and many may have multiple mating partners in order to produce more offspring if they do not die after one event. The ''M. paulensis'' species have higher breeding rates when the length of day is longer and there is more fruit available to eat.

Semelparity Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered ''semelparous'' if it is characterized by a single reproduction, reproductive episode before death, and ''iteroparous ...

also was found to occur in this species, but is hypothesized to occur only due to phylogenic constraints. It seems as though there is synchrony of the females for the species due to swollen nipples around the time of breeding. The ''M. incanus'' have also been found to exhibit semelparity with a distinct breeding season between the months of October through December. For the breeding season, it is more beneficial for the females to be larger in order to produce larger litters, yielding higher breeding success over the smaller sized females. When looking at milk production and food supply for the genus, there was a strong correlation found between the two as well. In times where there was more food, there was more milk produced by the females. As far as the males, they seem to generally disappear after the mating event while the females remain in the area until their young are done

weaning Weaning is the process of gradually introducing an infant human or other mammal to what will be its adult diet while withdrawing the supply of its mother's milk. In the United Kingdom, UK, weaning primarily refers to the introduction of solid ...

. This pattern leads to the generations being replaced every breeding season due to mortality of the adults. Overall, there is not much known about the reproductive patterns of the other species due to the little knowledge collected on the genus as a whole. There is a lack of pouch.

Species-specific information

The ''Marmosops noctivagus'' species have been involved in a big debate on which Genus they belong to. One study found them located in Columbia, which was previously an unknown location as far as ''Marmosops'' are concerned. They were identified by the chestnut brown hair on their back and white hair on their

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 ...

side along with black facial features. They also have long tails with two different colors. The ''M. noctivagus'' also has a skull with a long nose and cranial openings between the

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestra ...

and parietal bones. This is present in some of the animals and absent in others. The cranial openings under the squamosal bones, also known as

fenestra (anatomy) A fenestra (fenestration; : fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical structu ...

, are small and rounded. The dental arrangement for the species consists of large

canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, eye teeth, vampire teeth, or fangs, are the relatively long, pointed teeth. In the context of the upper jaw, they are also known as '' fangs''. They can appear more fl ...

but lack accessory cusps, correlating with the age and sex of the animal. These teeth are significantly smaller in the females. The ''Marmosops bishopi'' are another species of the genus ''Marmosops'' found in the western Brazilian

Amazon rainforest The Amazon rainforest, also called the Amazon jungle or Amazonia, is a Tropical and subtropical moist broadleaf forests, moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin ...

and other areas of Peru and Bolivia. ''Marmosops incanus'' are another species in the genus that have a mask made of black fur around their eyes. Some other distinguishing characteristics include the third digit being longer than the second and the fourth along with an extremely long tail. They do not have a fenestra on the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

, but the fenestra

cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus (cochlea), modiolus. A core component of the cochlea is the organ of Cort ...

is exposed The ''Marmosops creightoni'' is a species that is medium in size with a coat that is almost completely dark with no clear distinction between the

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 ...

and ventral sides. This is the only species of the genus without the white markings on the underside. The chin fur is white and continues down to the throat along with a black mask around the eyes. The skull consists of small orbits with long nasal bones and the

infraorbital foramen In human anatomy, the infraorbital foramen is one of two small holes in the skull's upper jawbone ( maxillary bone), located below the eye socket and to the left and right of the nose. Both holes are used for blood vessels and nerves. In anatomic ...

is very large. This species has a fenestra between the maxilla and

palatine bone In anatomy, the palatine bones (; derived from the Latin ''palatum'') are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxilla, they comprise the hard palate. Stru ...

, which are both long and narrow on each side. The palatine fenestra are rather small in size. The ''M. handleyi'' is one last species with very little known about it. However, rather recently there has been new information uncovered. The species is characterized by its woody dorsal fur, gray ventral fur and a rounded palatine fenestra. They are intermediately sized compared to the rest of the genus and have dark black facial masks. They were found to lack throat glands as well. They have white or light gray ears and the females are unique due to the odd rusty-red color of their mammary area with seven nipples located on the abdominal region.Diaz-N., J.F., Gomez’Laverde, M. and C.S. Giraldo. Rediscovery and redescription of Marmosops handleyi (Pine, 1982) (Didelphimorphia: Didelphidae), The Least Known Andean Slender Mouse Opossum. Mastozoologica Neotropical. 18:45-61.

References

External links

* "Gray Slender Mouse Opossu

* "The Slender Opossu

{{Authority control Marsupial genera Opossums Taxa named by Paul Matschie