655.

Sundaic Arboreal White-bellied Rat

Niviventer cremoriventer

French: Rat a ventre creme / German: Sunda-\Weif3bauchratte / Spanish: Rata de vientre blanco arborea de Sonda Other common names: Dark-tailed Niviventer, Dark-tailed Tree Rat, Sundaic Arboreal Niviventer Taxonomy. Mus cremoriventer G. S. Miller, 1900,

“mountains of Trong, Lower Siam [= Thailand], at about 3000 ft. [= 914 m] altitude.”

Niviventer cremoriventer has not been included in any phylogenetic studies and is in need of revision because it might represent a species complex. Subspecies have been recognized, but these need validation. Monotypic.

Distribution. Extreme S Myanmar (Mergui Archipelago), peninsular Thailand and offshore Is (Butang, Terutau, and Langkawi), Malay Peninsula and offshore Is (Penang and Tioman), Anambas Is (Jimaja), Sumatra and adjacent Nias, Belitung, and Bangka Is, Borneo and some offshore Is (Balambangan, Banggi, Malawali, Lamukutan, and Sebuku), Java, and Bali.

Descriptive notes. Head—body 133 mm, tail 181 mm; weight 77 g(averages). The Sundaic Arboreal White-bellied Rat is small, similar to the Langbian Tree Rat ( Chiromyscus langbianis). Pelage is soft, with flexible spines and black guard hairs mixed throughout. Dorsum is fulvous brown, becoming more orangish on sides. Dorsum and white venter are sharply demarcated. Feet have brown stripe that extends to white toes. Tail is c.136% of head-body length on average, covered in dark hairs, and unicolored (dark brown); it has dark hair tuft at tip. Ears are dark brown; vibrissae are long. There are five digits on each foot, with fifth digit reduced with small claw. Skull is elongated and narrow. There are four pairs of mammae: one pectoral, one post-axillary, one abdominal, and one inguinal. Chromosomal complement is 2n = 46, FN = 54 and 60.

Habitat. Primary forest, secondary wooded habitats, and disturbed logged habitat at elevations up to 1650 m (Mt. Kinabalu on Borneo).

Food and Feeding. The Sundaic Arboreal White-bellied Rat mainly eats fruit and seeds. Breeding. Sundaic Arboreal White-bellied Rats reach sexual maturity and 50 g; litters have 2-5 young.

Activity patterns. The Sundaic Arboreal White-bellied Rat is nocturnal, spending its days in a hanging nest it made. This species is arboreal but has regularly been captured on the ground as well as above it.

Movements, Home range and Social organization. Sundaic Arboreal White-bellied Rats create free-hanging nests made of plant fibers for day use.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. Although the Sundaic Arboreal White-bellied Rat has a large distribution and occurs in many protected areas, its population is estimated to have decreasedby ¢.30% in the last ten years due to habitat destruction and degradation. Nevertheless,it is easily and commonly captured throughout its distribution.

Bibliography. Duncan etal. (1974), Li Yuchun et al. (2008), Musser (1973b, 1981a), Musser & Carleton (2005), Nor (2001), Phillipps & Phillipps (2016), Pimsai et al. (2014), Ruedas, Aplin et al. (2008), Wells, Linsenmair et al. (2004), Wells, Pfeiffer et al. (2006), Yong (1969).