The titles for the smallest primate and smallest monkey go to different species, as not all primates are monkeys. As well as monkeys, primates also include the prosimians (such as lemurs), lesser apes (the gibbons), great apes (such as orangutans and gorillas) and humans.

What is the smallest monkey in the world?

The smallest monkey in the world accolade is awarded to two species of pygmy marmoset, found in South America, including Bolivia, Brazil, Columbia, Ecuador, and Peru.

The two – the Western pygmy marmoset (Cebuella pygmaea) and the Eastern pygmy marmoset (C. niveiventris) – used to be considered two subspecies of the same species, but a scientific paper published in Molecular Phylogenetics and Evolution in 2018 split them into two separate species. The two are very similar in morphology, and are separated by geographical barriers such as large rivers.

Pygmy marmosets weigh just over 100g, and measure between 11.7-15.2cm in head-body length.

What is the smallest primate in the world?

In the dry deciduous forests of western Madagascar, there lives a tiny primate that measures just 9-9.5cm in body length and weighs 30g. Called Madame Berthe’s mouse lemur or Berthe’s mouse lemur, it is the smallest primate in the world.

It was only described as a new species in 1992 and was first thought to be the pygmy mouse lemur, but further studies revealed it was a undescribed species.

Main image: Madame Berthe’s mouse lemur in the Kirindy Forest in Madagascar. © FC Casaurio/via Wikimedia (used under CC4.0)


Megan ShersbyNaturalist, writer and content creator