Lesser marmoset rat  (Hapalomys delacouri)

The lesser marmoset rat is classified as Vulnerable (VU) on the IUCN Red List (1).

The lesser marmoset rat (Hapalomys delacouri) is a small, rat-like rodent which is well adapted to its arboreal lifestyle in bamboo habitats of South East Asia (3) (4).

The thick, soft fur of the lesser marmoset rat is dark-reddish brown, with tinges of orange (4). The fur on the sides and underparts is generally slightly paler than the fur on the back (2). The lesser marmoset rat has long, prominent whiskers (2) (4), and relatively long brown ears which are fringed with very long, fine hairs (2) (3).

The tail of the lesser marmoset rat can exceed the length of its body and head, and this, along with the extended toes on its hind legs, is thought to be an adaptation for climbing (4). It also has an opposable hind toe, which bears a flattened nail instead of a claw (2) (3) (4).

The lesser marmoset rat occurs in South East Asia, in China, Lao People’s Democratic Republic and northern Vietnam (1) (2) (3) (4).

The lesser marmoset rat inhabits areas of bamboo within lush tropical wet and dry forests, on mountains and hills. It occurs at elevations between 1,200 and 1,500 metres (1) (2) (3).

A nocturnal rodent (3), the lesser marmoset rat rests during the day within the hollow stem of a bamboo shoot. By gnawing a small, circular hole in the bamboo stem, the marmoset rat can crawl into the cavity, which it lines with bamboo leaves to create a nest (4). A skilful climber, the lesser marmoset rat appears to be strictly associated with its bamboo habitat (4).

The diet of this little-known rodent is thought to consist of the shoots, flowers and fruits of bamboo (4).

The main threat facing the lesser marmoset rat is habitat destruction (1). The stands of bamboo on which the lesser marmoset rat depends are already fairly scarce, and the remaining stands are being harvested to be used in construction and other activities (1). Large areas of hill forest within this species’ range have also been converted to agriculture (3).

The lesser marmoset rat appears to be sensitive to human disturbance, and is not found in modified habitats (1).

The lesser marmoset rat occurs in Cat Tien National Park in Vietnam, which should hopefully offer its habitat some protection. However, it is currently not the focus of any specific conservation measures (1).

Due to the lesser marmoset rat’s dependence on bamboo, the protection of remaining areas of bamboo is vital for its survival. It will also be important to undertake further surveys to locate remaining habitat patches, as well as to perform further studies into the biology and populations of this poorly known rodent (1).

Find out more about rodent conservation:

• Lidicker Jr, W.Z. (1989) Rodents: A World Survey of Species of Conservation Concern. IUCN/SSC Rodent Specialist Group, IUCN, Gland. Available at:
  http://data.iucn.org/dbtw-wpd/edocs/SSC-OP-004.pdf