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 (anatomical term) 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.
Taxonomy
The genus Marmosops includes the following species: Bishop's slender opossum (M. bishopi) Narrow-headed slender opossum (M. cracens) Creighton's slender opossum (M. creightoni) Dorothy's slender opossum (M. dorothea) Dusky slender opossum (M. fuscatus) Handley's slender opossum (M. handleyi) Tschudi's slender opossum (M. impavidus) Gray slender opossum (M. incanus) Panama slender opossum (M. invictus) Junin slender opossum (M. juninensis) Neblina slender opossum (M. neblina) White-bellied slender opossum (M. noctivagus) Spectacled slender opossum (M. ocellatus) Delicate slender opossum (M. parvidens) Brazilian slender opossum (M. paulensis) Pinheiro's slender opossum (M. pinheiroi)
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. The genus Marmosops is frequently misidentified and lumped into groups containing other species. 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.
Habitat
The main habitat for the Marmosops is found between the Neotropical humid forests ranging from Panama to the South of Brazil 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) 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 of the genus due to their migration patterns and unique preferences.
Diet
The diet of Marmosops includes, but is not limited to fruit, arthropods, flowers and small vertebrates. They also will eat insects, 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.