''Marmosops pakaraimae'', the Pantepui slender opossum, is a species of

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 ...

within the genus

Marmosops ''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 ...

Distribution

''Marmosops pakaraimae'' is known from five localities, with three in the Pakaraima Highlands of western

Guyana Guyana, officially the Co-operative Republic of Guyana, is a country on the northern coast of South America, part of the historic British West Indies. entry "Guyana" Georgetown, Guyana, Georgetown is the capital of Guyana and is also the co ...

and two in adjacent highlands of eastern

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

. Recorded elevations at these localities range from 800 to approximately 1500 m above sea level. ''Marmosops pakaraimae'' is one of only seven

mammalian A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

species known to be

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Pantepui region. While the endemic flora and avian fauna of this area have been relatively well-studied, mammalian endemism remains limited. Prior to the description of ''Marmosops pakaraimae'', the only didelphid marsupials known to be restricted to the region were ''

Marmosa tyleriana Tyler's mouse opossum (''Marmosa tyleriana'') is a South American marsupial of the family Didelphidae. It lives in rainforests of the Guiana Highlands of southern Venezuela at elevations between 1300 and 2200 m. The species has only been found ...

'' and '' Monodelphis reigi''.

Description

''Marmosops pakaraimae'' is a small species within the genus

, exhibiting all diagnostic qualitative traits typical of the genus. The 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 ...

is dark brown (near dark

umber Umber is a natural earth pigment consisting of iron oxide and manganese oxide; it has a brownish color that can vary among shades of yellow, red, and green. Umber is considered one of the oldest pigments known to humans, first used in the Ajant ...

) dorsally, with indistinctly paler lateral coloration and a superficially whitish ventral side. The hairs of the throat, chest, and abdomen are uniformly gray-based, with self-white fur limited to the apex of the chin, oral margins, and

scrotum In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin ...

. ''Marmosops pakaraimae'''s long tail is substantially longer than the combined length of the head and body (mean LT/HBL × 100 = 150%). It possesses long

nasal bones The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

that are wider posteriorly than anteriorly, a very broad

interorbital region The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups. In oryzomyine rodents, for example, the width, form, and ...

, and rounded supraorbital margins. The species also features unique dental characteristics, including short upper canines with both anterior and posterior accessory cusps, as well as specific traits in the lower

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

Morphological comparisons

''Marmosops pakaraimae'' averages larger than '' Marmosops parvidens'' in all measured external dimensions except ear length, with notable differences in dorsal and ventral pelage coloration. The species is also larger than ''Marmosops'' ''pinheiroi'', with comparable differences in coloration and morphology, particularly in cranial measurements and dental characteristics.

References

{{Taxonbar, from=Q18474206 Opossums Mammals of Guyana Mammals of Venezuela Fauna of South America