Niviventer tenaster (Thomas 1916)

[Niviventer] tenaster (Thomas 1916), Ann. Mag. Nat. Hist., ser. 8, 17: 425.

Type Locality: S Burma (Kayin State), Mulayit (also spelled Mooleyit, Mulaiyit, Muleyit) Taung (= peak) (16°11'N / 98°32'E), 5000-6000 ft (1525-1830 m).

Vernacular Names: Indochinese Mountain Niviventer.

Synonyms: Niviventer champa (Robinson and Kloss 1922); Niviventer lotipes (G. M. Allen 1926) .

Distribution: Mountains of WC (Mt Victoria) and S (Mulayit Taung) Burma, NW Thailand (Doi Pui and Doi Suthep, Chiengmai Province), S Cambodia (Elephant Mtns), S Laos, Vietnam, and in China in the Tengchong region of W Yunnan (east of the Salween River bordering N Burma; specimens in IZAS, D. Lunde, in litt., 2004); also on Hainan Isl off southern coast of China; probably occurs in mountains of N Laos. Range primarily derived from specimens identified by Musser in AMNH, BMNH, FMNH, IEBR, USNM, and ZMA; also see Lunde et al. (2003 b).

Conservation: IUCN – Lower Risk (lc).

Discussion: Originally described as a species, tenaster was later arranged as a subspecies of N. cremoriventer (Ellerman, 1941, 1961; Ellerman and Morrison-Scott, 1951) until the type specimens were shown to represent a separate species (Musser, 1973 c, 1981 b). The large-bodied and montane N. tenaster is morphometrically most closely related to N. confucianus among species of Niviventer (Musser and Lunde, ms). Analysis of mtDNA cytochrome b sequences points to N. coninga as the close ally of N. tenaster, and clusters both within a monophyletic clade also containing N. confucianus and N. culturatus (J. L. Patton, in litt., 2000; N. fulvescens and N. langbianis were the only other Niviventer sampled). Niviventer tenaster is restricted to montane habitats in Indochina mostly beyond the range of N. confucianus, and is sympatric in some places with N. fulvescens and N. langbianis (Lunde et al., 2003 b; Musser, 1981 b; specimens in AMNH and IEBR) In NE Vietnam, N. tenaster occurs on the same mountain (Fan Si Pan) as N. confucianus, but at lower montane altitudes (Musser and Lunde, ms). Mountains in N Burma, where N. tenaster might also be expected, are instead occupied by N. confucianus, N. fulvescens and an undescribed species larger in body size than N. tenaster, darker in fur coloration, and morphometrically unrelated (Musser and Lunde, ms). Robinson and Kloss (1922) described champa as a subspecies of Rattus bukit, and lotipes was proposed as a subspecies of Rattus confucianus by G. M. Allen (1926); morphometric analyses closely cluster large samples from type localities of both taxa (which includes holotypes) with samples of N. tenaster from elsewhere in the range (Musser and Lunde, ms). Karyotype of sample from Dalat Plateau in Vietnam recorded by Baskevich and Kuznetsov (2000).