725.

Langbian Tree Rat

Chiromyscus langbianis

French: Rat du Lang Bian / German: Langbian-Fea-Baumratte / Spanish: Rata arboricola de Langbian

Other common names: Indochinese Arboreal Niviventer, Langbian Masked Tree Rat

Taxonomy. Rattus cremoriventer langbianus H. C. Robinson & Kloss, 1922,

“Langbian Peaks, South Annam, 5500-6500 ft. [= 1676-1981 m].”

Traditionally, langbianis was included under Nwiventer and even included as a subspecies of N. cremoriventer . It was moved to Chiromyscus based on genetic and morphological data. There are two genetic lineages, one in the northern part of the distribution and one in the southern part, but additional studies are needed to determine if they represent distinct taxa.

Distribution. NE India, W, extreme E & SE Myanmar, N & W Thailand, Laos, Vietnam, NE & SW Cambodia, and an isolated record from Yunnan, SW China.

Descriptive notes. Head-body 135-155 mm, tail 154-199 mm, ear 19-22 mm, hindfoot 29-33 mm; weight 58-98 g. The Langbian Tree Rat is medium-sized and less colorful than other species of Chiromyscus . Pelage is dense, smooth, downy, and overall dull and grayish, with hints of fulvous and sometimes an olive hue. Dorsum contrasts sharply with pure white or cream venter, which occasionally has brown or fulvous spots. Tail is slender, 135-155% of head—body length, covered in hair, dark chocolate brown proximally, and unicolored without terminal brush. Vibrissae are very long, extending back beyond head, and ears are short and rounded. Forefeet and hindfeet have broad brown or chestnutstripe on dorsal sides that extends beyond middle of feet, disappearing near white fingers. Claws are short compared with other species of Chiromyscus but are curved and sharp. There are five toes on forefeet and hindfeet, and unlike other species of Chiromyscus, hallux has nail-like claw. There are four pairs of mammae: one pectoral, one post-axillary, one abdominal, and one inguinal pairs. Skull is very gracile for the genus, with less developed orbital ridges. Chromosomal complement 1s 2n = 46, FN = b4.

Habitat. Seasonal deciduous and tropical evergreen forests, lightly disturbed forests, and primary and secondary habitats at elevations of 60-2800 m.

Food and Feeding. No information.

Breeding. No information.

Activity patterns. The Langbian Tree Ratis nocturnal and can shelter in vines and dense foliage when inactive. It is arboreal and caught frequently in trees, although it is caught occasionally on the ground and in shrubs. Throughout its distribution,it is sympatric with theterrestrial Indochinese White-bellied Rat (Niviventerfulvescens), with which it is often confused.

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The IUCN Red List. The Langbian Tree Rat is relatively common throughout most ofits distribution and can be found in lightly disturbed forest. It is found in various nature reserves. Population levels are unknown but may be declining as a result of forest clearing.

Bibliography. Abramov et al. (2006), Aplin, Lunde, Musseret al. (2016), Balakirev, Abramov & Rozhnov (2014), Balakirev, Abramov, Tikhonov & Rozhnov (2012), Cao Van Sung & Tran Van Minh (1984), Francis (2008), Musser (1973b, 1981a), Nguyen Minh Tam et al. (2003), Robinson & Kloss (1922), Smith & Yan Xie (2008).