Hapalomys longicaudatus Blyth 1859

162.

Greater Marmoset Rat

Hapalomys longicaudatus

French: Grand Hapalomys / German: Langschwanz-Seidenratte / Spanish: Rata titi mayor

Other common names: Marmoset Rat

Taxonomy. Hapalomys longicaudatus Blyth, 1859,

Sittaung River Valley, Tenasserim, Burma (= Myanmar).

This species is monotypic.

Distribution. Known only from scattered localities on Peninsular Malaysia; it may be extirpated in most ofits historical distribution in SE Myanmar (Bago Division and Mon State) and W & Peninsular Thailand.

Descriptive notes. Head-body 140- 165 mm, tail 176-202 mm, ear 12-15 mm, hindfoot 28-32 mm. No specific data are available for body weight. The Greater Marmoset Rat is stocky and highly arboreal, with thick, soft, and woolly fur and grayish brown upperparts, white below with contrasting ocherous strip between the two. Underparts have pale ocherous suffusion on some individuals. Head is broad with short snout; uppersurface extending onto cheeks and lips is darker than back. Ears are relatively small, dark brown, and conspicuously fringed by elongate black hair. All vibrissae are black and long, and mystacial group folds back past ears. Forefeet and hindfeet are short and broad, clearly adapted to climbing, with large terminal and plantar pads. Hallux is wide and has a nail; all other digits have strong, curved claws. Basal part of hindfeet have dark hairs; remainder of hindfeet are white. Tail is 30 mm or more longer than head-body length, dark, and finely scaled; tail hairs are conspicuous on distal 30% oftail, and terminal brush is conspicuous. Cranium is broad, deep, and compact, with broad heavy incisors, large cuspidate molars, and inflated auditory bullae. Four mammae are on each side: one pectoral, one post-axillary, and two inguinal pairs.

Habitat. Lowland tropical evergreen forest at elevations of ¢.500 m. All records of the Great Marmoset Rat are associated with clumps of bamboo within regional forest habitat, and there are no records from any highly modified habitats.

Food and Feeding. The Greater Marmoset Ratis probably exclusively herbivorous, but details are uncertain. Stomachs of wild caught individuals in Malaysia contained white pulpy material, with abundant pollen, and possibly all derived from bamboo. Captive individuals consumed papaya, banana, sweet potato, and rice, but only thrived if given growing or flowering shoots of bamboos. Somefruit was ignored if water was provided, and animal foods including raw meat and bones were ignored.

Breeding. Greater Marmoset Rats construct leaf nests in internodes ofdead or living bamboo culms. In Cameron Highlands, Gigantochloa scortechinii (Poaceae) is used, and occupied culms average 10-8 cm in diameter, with minimum diameter of 8-5 cm. Internodal spaces of culms are accessed by gnawing a circular hole with average diameter c.3b cm, and several internodes are often linked by internal holes. Additional exits are sometimes gnawed. Holes gnawed from the outside are ringed by a zone 1 cm wide from which green outer layer has been stripped; those gnawed from the inside lack this feature. Nests are constructed exclusively of bamboo leaves.

Activity patterns. Body form suggests highly arboreallifestyle, and this is supported by observations of captive individuals that are capable of climbing nearly vertical fresh bamboo culms, using bounding locomotion with digital pads rather than claws providing traction. Descent is usually done head first. Long tail is not prehensile but is used as a counterbalance or pressed sideways against a branch or stem as a stabilizing organ.

Movements, Home range and Social organization. Nests of Greater Marmoset Rats appear to house single individuals and presumably females with young.

Status and Conservation. Classified as Endangered on The IUCN Red List. The Greater Marmoset Rat is thought to be extirpated across much ofits historical distribution because of conversion of lowland tropical evergreen forests into plantations and agricultural fields.

Bibliography. Blyth (1859), Clayton (2016k), Ellerman (1941), Marshall (1977b), Medway (1964a, 1978), Musser (1972), Wang Yingxiang (2003).