A Pygmy slow loris is a small, compact creature with a short tail, a short, rounded muzzle, round eyes that are directed forward and fur that is short and dense. They are mostly brown, gray or reddish-brown. Between their eyes are white lines, with dark markings encircling them, and a faint medial stripe on the crown. Their hands are broad and they have an opposable thumb. The two genders are similar in appearance.
The Pygmy slow loris occurs east of Vietnam’s Mekong River, in eastern Cambodia, Laos, and the Yunnan province in the south of China. It inhabits primary and secondary rainforests as well as degraded habitats, and also occurs in evergreen forest in Laos and bamboo thickets in Vietnam.
Pygmy slow lorises are arboreal, nocturnal quadrupeds. They remain in trees almost exclusively, except on rare occasions when potential predators threaten them. They are thought to move about almost constantly throughout the night during warmer months. In winter months they can enter a state of torpor, living off the fat stored in their bodies. At this time they reduce their activity, they do not forage, and they lower their body temperature and metabolic rate. This hibernation-like behavior takes place in the wild as well as in captivity. As pygmy slow lorises have been studied very little in the wild, numerous aspects of the behavior of this species are as yet unknown. Generally considered solitary, the pygmy slow loris is occasionally described as "gregarious" because of their mating behavior.
The Pygmy slow loris is an omnivore, eating ants, insects, and a wide variety of fruits and plants, preferring soft fruits and gums, though it will readily eat tender shoots and other parts of plants.
This species is polygynous. A male's territory usually includes that of several females with which he mates. Individuals communicate with each other through whistles. Scent is used as cue to find a mate. Female pygmy slow lorises give birth every 12 to 18 months from July to October. The gestation period is about 6 months, and 1 to 2 offspring are born, 2 being common. Births occurs in the open, with infants being born fully formed and covered with fur and with their eyes open. As soon as they are born, infants will cling to their mother's belly. Later, mothers "park" their babies in a safe place while they go foraging. Babies are nursed for 4.5 months on average, though sometimes weaning occurs after 8 months. Females are sexually mature at about 9 months old and males at 18 to 20 months old.
The Pygmy slow loris is under threat by severe habitat degradation within the areas where it lives. For example, in Yunnan in China, forest cover has decreased by 42 percent since the time of the mid-1990s, and in Vietnam as a result of the war, 30 percent of original forest cover is all that remains. The impacts of habitat loss from logging, defoliant spray and military activities is made worse by hunting of this species for food, for the pet trade, and for use in the traditional medicine of the Khmer people of Cambodia.
According to IUCN, Pygmy slow loris is widespread throughout its range but no overall population estimate is available. Today this species’ numbers are decreasing and currently it is classified as Vulnerable (VU) on the IUCN Red List.
Due to consuming a large amount of fruit, Pygmy slow lorises probably have a role in seed dispersal.