''Microsciurus'' or dwarf squirrels is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 ...

s from the tropical regions of Central and South America.

Taxonomy and systematics

Recent DNA analysis has shown that there is some confusion regarding the traditional classification of the species in the genus ''Microsciurus'', and that the genus may be

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

. Currently, there are four

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

recognized: *

Central American dwarf squirrel The Central American dwarf squirrel, also known as Alfaro's pygmy squirrel,(''Microsciurus alfari'') is a small tree squirrel in the genus ''Microsciurus'' and Tribe (biology), tribe Sciurini found in Colombia, Costa Rica, Nicaragua, and Panama. ...

(''Microsciurus alfari'')

Allen Allen, Allen's or Allens may refer to: Buildings * Allen Arena, an indoor arena at Lipscomb University in Nashville, Tennessee * Allen Center, a skyscraper complex in downtown Houston, Texas * Allen Fieldhouse, an indoor sports arena on the Univer ...

, 1895, Costa Rica, Nicaragua, Panama, northern Colombia *

Amazon dwarf squirrel The Amazon dwarf squirrel (''Microsciurus flaviventer'') is a chipmunk-sized tree squirrel native to South America. Description As its name suggests, the Amazon dwarf squirrel is relatively small, with a head-body length of and a tail long. Ad ...

(''Microsciurus flaviventer'') Gray, 1867, western

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

Western dwarf squirrel The western dwarf squirrel (''Microsciurus mimulus'') is a small tree squirrel in the genus ''Microsciurus'' and tribe ''Sciurini'' found in Colombia, Ecuador, and Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of ...

(''Microsciurus mimulus'')

Thomas Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (disambiguation) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the Ap ...

, 1898, Ecuador, Colombia, Panama *

Santander dwarf squirrel The Santander dwarf squirrel (''Microsciurus santanderensis'') is a small tree squirrel endemic to Colombia. Description The Santander dwarf squirrel is a small tree squirrel, measuring around from nose to rump, with a tail about the same lengt ...

(''Microsciurus santanderensis'') Hernández-Camacho, 1957, central Colombia A 2020 paper published on the taxonomy of

Sciurinae Sciurinae is a subfamily of squirrels (in the family Sciuridae), uniting the flying squirrels with certain related tree squirrels. Older sources place the flying squirrels in a separate subfamily (Pteromyinae) and unite all remaining sciurids into ...

split ''Microsciurus'' into three genera, one currently unnamed. The paper included genetic sampling from all species except

and '' (Microsciurus) simonsi''. It suggests several new species, not all described. *''Microsciurus'' **

, ''M. alfari'' **''Microsciurus "species 1"'' from Colombia *''Leptosciurus'' **

, ''L. mimulus'' **

Andean squirrel The Andean squirrel (''Sciurus pucheranii'') is a tree squirrel endemic to Colombia where it inhabits montane rain forest and cloud forests of the Cordillera Occidental and Cordillera Central ranges of the Colombian Andes, at elevations betwe ...

, ''L. pucheranii'' (moved from ''

Sciurus The genus ''Sciurus'' contains most of the common, bushy-tailed squirrels in North America, Europe, temperate Asia, Central America and South America. Species The number of species in the genus is subject to change. In 2005, Thorington & Hoffma ...

'') **'' Leptosciurus similis'' **'' Leptosciurus otinus'' **'' Leptosciurnus boquetensis'' **'' Leptosciurus isthmius'' *''"Microsciurus"'' **

, ''"M." flaviventer'' ** "Microsciurus" sabanillae **''"Microsciurus" "species 2"'' from Peru and Brazil (previously assigned to ''

Syntheosciurus Bangs's mountain squirrel (''Syntheosciurus brochus'') is a poorly known species of tree squirrel, that only lives in Costa Rica and Panama. It can be found in mountain rain forests at an altitude between , and lives mainly in the tree tops, but ...

'')

Description

With a typical head-and-body length of about and a long tail, dwarf squirrels are relatively small. However, the

Neotropical pygmy squirrel The Neotropical pygmy squirrel (''Sciurillus pusillus'') is a South American species of tree squirrel, being the only living species in the genus ''Sciurillus'' and the subfamily Sciurillinae. Genetic analysis has shown it to be the sister group ...

, not in this genus, is much smaller than these species, as are certain squirrels in Africa and Asia. ''Microsciurus'' species have gray or brown backs, and white bellies.

Distribution and habitat

All dwarf squirrels in this genus live in

tropical rain forest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatori ...

s. Estimates of their abundance are limited. The IUCN lists the conservation status as "Least Concern" for three of the species and "Data Deficient" for '' Microsciurus santanderensis''.

References

Bibliography

* Ronald M. Nowak: ''Walker's Mammals of the World''. Johns Hopkins University Press, 1999 {{Taxonbar, from=Q948353 Rodent genera Rodents of Central America Mammals of South America Taxa named by Joel Asaph Allen