The Neotropical pygmy squirrel (''Sciurillus pusillus'') is a South American species of

tree squirrel Tree squirrels are the members of the squirrel Family (biology), family (Sciuridae) commonly just referred to as "squirrels." They include more than 100 arboreal species native to all continents except Antarctica and Oceania. They do not form a ...

, being the only living species in the genus ''Sciurillus'' and the subfamily Sciurillinae. Genetic analysis has shown it to be the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to all other

squirrel Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

Description

The Neotropical pygmy squirrel is the smallest species of tree squirrel native to the Americas, measuring on average just in head-body length, with an 11-cm tail. Adults weigh from . The fur is grizzled grey over the body, with paler, but not sharply contrasting, fur on the underparts. The head is slightly reddish, with distinct white markings behind the ears, which are shorter and more rounded than on most other tree squirrels. The limbs are slender, with the fore limbs elongated to assist in climbing. Females have six

teat A teat is the projection from the mammary glands of mammals from which milk flows or is ejected for the purpose of feeding young. In many mammals the teat projects from the udder. The number of teats varies by mammalian species and often corre ...

Distribution and habitat

Neotropical pygmy squirrels inhabit at least four widely separated regions in northern South America, in

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...

Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...

, central

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, northern

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, and southern

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

. Within these regions, they inhabit lowland tropical

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

s. Three subspecies are currently recognised, although their respective geographic distributions are unclear, and these may represent two or more distinct species. * ''S. p. pusillus'' (E. Geoffroy, 1803) * ''S. p. glaucinus'' Thomas, 1914 * ''S. p. kuhlii'' (Gray, 1867)

Biology and behaviour

Neotropical pygmy squirrels are diurnal and spend the day in the forest canopy, usually at least above the ground. They have been observed nesting in abandoned arboreal

termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...

nests lined with fibres gathered from the machimango (''

Eschweilera ''Eschweilera'' is a genus of woody plants in the family Lecythidaceae first described as a genus in 1828.Parkia ''Parkia'' is a genus of flowering plants in the family Fabaceae. It belongs to the mimosoid clade of the subfamily Caesalpinioideae. Several species are known as African locust bean. In 1995, about 31 species were known.Melissa Luckow and ...

'', and probably eating either the gummy exudates produced by the trees in response to injury or the

cambium A cambium (plural cambia or cambiums), in plants, is a tissue layer that provides partially undifferentiated cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant tissue from w ...

beneath the bark. Population densities are apparently low, with normally no more than three individual per km², although groups containing more than one adult, plus young, have been observed in areas with a local concentration of food. These squirrels typically move rapidly through the trees, and are highly excitable, giving an alarm call described as similar to the sound of a

cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striki ...

. They give birth to one or two young at a time, with pregnant females having been observed in June.

Description

Distribution and habitat

Biology and behaviour

References

Further reading