Pygmy Marmoset Explained... 🐒🍉✨
Pygmy marmosets are two species of small New World monkeys in the genus Cebuella. They are native to rainforests of the western Amazon Basin in South America. These primates are notable for being the smallest monkeys in the world, at just over 100 g (3.5 oz). They are generally found in evergreen and river-edge forests and are gum-feeding specialists, or gummivores.
About 83% of the pygmy marmoset population lives in stable troops of two to nine individuals, including a dominant male, a breeding female, and up to four successive litters of offspring. The modal size of a standard stable troop would be six individuals. Although most groups consist of family members, some may also include one or two additional adult members. Members of the group communicate using a complex system including vocal, chemical, and visual signals. Three main calling signals depend on the distance the call needs to travel. These monkeys may also make visual displays when threatened or to show dominance. Chemical signaling using secretions from glands on the chest and genital area allow the female to indicate to the male when she is able to reproduce. The female gives birth to twins twice a year and the parental care is shared among the group.
The pygmy marmoset has been viewed as somewhat different from typical marmosets, most of which are classified in the genera Callithrix (where they were placed in a subgenus) and Mico, and thus is accorded its own genus, Cebuella, within the family Callitrichidae. Their biggest threats are habitat loss and the pet trade.
Debate has arisen among primatologists concerning the proper genus in which to place the pygmy marmoset. An examination of the interstitial retinol binding protein nuclear gene (IRBP) in three marmoset species showed that Callithrix as constructed in the 1990s also needed to include C. pygmaea to be monophyletic, and that the times of separation of pygmaea and the argentata and jacchus species groups from one another are less than 5 million years ago, as might be expected for species of the same genus. However, subsequent separation of the argentata and jacchus species groups into different genera (the argentata group having been moved to Mico) justifies maintaining a separate genus for the pygmy marmosets, as Callithrix is no longer paraphyletic.
Few morphological differences occur between these species, as they may only differ slightly in color, and they are only separated by geographical barriers, including large rivers in South America.
The evolution of this genus diverged in terms of body mass from typical primates, with a high rate of body-mass reduction. This involves large decreases in prenatal and postnatal growth rates, furthering the thought that progenesis played a role in the evolution of this animal.
Pygmy marmosets are the smallest true monkey, with a head-body length ranging from 117 to 152 mm (4.6 to 6.0 in) and a tail of 172 to 229 mm (6.8 to 9.0 in). The average adult body weight is just over 100 g (3.5 oz) with the only sexual dimorphism of females being a little heavier. The fur colour is a mixture of brownish-gold, grey, and black on its back and head and yellow, orange, and tawny on its underparts. Its tail has black rings and its face has flecks of white on its cheeks and a white vertical line between its eyes. It has many adaptations for arboreal living, including the ability to rotate its head 180° and sharp, claw-like nails used to cling to branches and trunks of trees. Its dental morphology is adapted to feeding on gum, with specialised incisors that are used to gouge trees and stimulate sap flow. The cecum is larger than usual to allow for the greater time gum needs to break down in the stomach. Pygmy marmosets walk on all four limbs and can leap up to 5 m (16 ft) between branches.
Pygmy marmosets can be found in much of the western Amazon Basin, in Brazil, Colombia, Ecuador, Peru, and Bolivia. The western pygmy marmoset, C. pygmaea, occurs in the state of Amazonas, Brazil, eastern Peru, southern Colombia, and north-eastern Ecuador. The eastern pygmy marmoset, C. niveiventris, is also found in Amazonas, but also in Acre, Brazil, eastern Peru, and northern Bolivia. The distribution of both species is often limited by rivers. They typically live in the understory of the mature evergreen forests and often near rivers. Population density is correlated with food-tree availability. They can be found between ground level and about 20 m (66 ft) into the trees, but generally do not enter the top of the canopy. They are often found in areas having standing water for more than three months of the year.
These monkeys have a specialized diet of tree gum. They gnaw holes in the bark of appropriate trees and vines with their specialized dentition to elicit the production of gum. When the sap puddles up in the hole, they lap it up with their tongues. They also lie in wait for insects, especially butterflies, which are attracted to the sap holes.