Despite its name, the Pygmy Marmoset is somewhat different from the typical marmosets, most of which are classified in the genera Callithrix and Mico; as such, it is accorded its own genus, Cebuella.
Nicknames for this monkey often refer to its diminutiveness, as in the following two examples: mono de bolsillo ("pocket monkey") and leoncito ("little lion").
The Pygmy Marmoset has a tawny coat, and a ringed tail that can be as long as its body. In common with other callitrichids, it has claws instead of nails on all its digits except the big toe. It is omnivorous, feeding on fruit, leaves, insects, and sometimes even small reptiles. Its small weight allows it to reach the very highest leaves of a tree, and to exploit the otherwise little-used food sources there. Much of its diet, however, comes from tapping trees for sap. Up to two-thirds of its time is spent gouging tree bark to reach the gummy sap. The Pygmy Marmoset has specialized incisors for gouging holes in bark. Because of its small size, and its swift movements, it is very hard to observe in the wild.
The Pygmy Marmoset uses special types of communication to give alerts and warning to its family members. These include chemical, vocal, and physical types of communication. A trill to communicate over long distance. A sharp warning whistle and a clicking sound for signaling danger to their family members. A J-call is a series of fast notes repeated by the caller and is for medium distances.
There are two subspecies of the Pygmy Marmoset:
- Cebuella pygmaea pygmaea
- Cebuella pygmaea niveiventris
