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 Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''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 ...

to all other squirrels.

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 teats.

Distribution and habitat

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

French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...

Suriname Suriname, officially the Republic of Suriname, is a country in northern South America, also considered as part of the Caribbean and the West Indies. It is a developing country with a Human Development Index, high level of human development; i ...

, central

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 ...

, northern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

, and southern

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

. Within these regions, they inhabit lowland tropical

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

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 a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

nests lined with fibres gathered from the machimango ('' Eschweilera'') tree. They feed by gnawing on the bark of trees, especially those of the genus '' Parkia'', and probably eating either the gummy exudates produced by the trees in response to injury or the cambium 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 games, bat-and-ball game played between two Sports team, teams of eleven players on a cricket field, field, at the centre of which is a cricket pitch, pitch with a wicket at each end, each comprising two Bail (cr ...

. 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