The Roosmalens' dwarf marmoset (''Mico humilis''), also known as the black-crowned dwarf marmoset, is a small

New World monkey New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboid ...

native to the Amazon Rainforest, on the east bank of the lower

Madeira River The Madeira River ( pt, Rio Madeira, link=no ) is a major waterway in South America. It is estimated to be in length, while the Madeira-Mamoré is estimated near or in length depending on the measuring party and their methods. The Madeira is ...

, and the west bank of the Aripuanã River, in

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 ...

. It has the smallest distribution of any primate in Amazonia. This marmoset has several unique attributes, which has resulted in it sometimes being placed in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Callibella. However, genetic analysis has subsequently resulted in its being classified within the genus '' Mico''. It was first described in 1998, after it was discovered ca. 400 km (250 mi) south of the city of Manaus. In 1996, Marc van Roosmalen, the discoverer, was given a milk can by a river trader with one of these monkeys inside. He suspected it was a new species, a relative of the

pygmy marmoset Pygmy marmosets are two species of small New World monkeys in the genus ''Cebuella''. They are native to Amazon rainforest, rainforests of the western Amazon Basin in South America. These primates are notable for being the smallest monkeys in th ...

, but at that point was unaware of its exact origin. Following a lengthy expedition, it was discovered near the town of Nova Olinda in southeastern Amazonas. The species has been subsequently recorded further south, along the west banks of Rio Roosevelt. Adult Roosmalens' dwarf marmosets have a total length of 38–39 cm (15-15½ in), incl. a tail of 22–24 cm (8½–9½ in), and weigh 150–185 g (5½–6½ oz). It is the second smallest species of

monkey Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, which constitutes an incom ...

, with only the related pygmy marmoset being smaller. The upperparts of Roosmalens' dwarf marmoset are mainly dark olive-brown, while the underparts are pale, dull yellowish. The bare, pale pinkish face is bordered by a whitish ring of hair. The crown is blackish, as suggested by its alternative

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contra ...

; black-crowned dwarf marmoset. It has claws as opposed to nails, like other marmosets who feed off tree

sap Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a separ ...

. It also has teeth similar to other marmosets. It is considered unusual among marmosets in that it gives birth to only a single baby instead of twins, the norm for marmosets. Marmosets are often very territorial, though this is not the case among Roosmalens' dwarf marmoset, where it is common for multiple females in a group to have young, instead of one dominant female.

References

{{Taxonbar, from1=Q18365864, from2=Q19826006, from3=Q1191128 Roosmalens' dwarf marmoset Mammals of Brazil Endemic fauna of Brazil Roosmalens' dwarf marmoset Taxobox binomials not recognized by IUCN