Mus (Mus) cookii Ryley 1914

Mus (Mus) cookii Ryley 1914, J. Bombay Nat. Hist. Soc., 22: 663.

Type Locality: N Burma, Shan States, Gokteik, 2133 ft (650 m).

Vernacular Names: Cook's Mouse.

Synonyms: Mus (Mus) darjilingensis Hodgson 1849; Mus (Mus) nagarum (Thomas 1921); Mus (Mus) palnica (Thomas 1923); Mus (Mus) rahengis (Kloss 1920); Mus (Mus) thai (Kloss 1917) .

Distribution: India (disjunct, one part in S Peninsular India, the other in the northeast; Agrawal, 2000), Nepal through Burma and S China (SW Yunnan; Wang, 2003; Zhang et al., 1997, as M. famulus cookii) to N and C Thailand (J. T. Marshall, Jr., 1977 a; Robinson et al., 1995), Laos (Smith et al., In Press), and Vietnam (Dang et al., 1994).

Conservation: IUCN – Lower Risk (lc).

Discussion: Subgenus Mus . Revised by J. T. Marshall, Jr. (1977 b) and reviewed by Corbet and Hill (1992). Analysis of sequences from the Sry gene indicates close alliance with M. cervicolor (Graur, 1994), and combined analyses of morphological traits, DNA/DNA hybridization, and mitochondrial 12S rRNA sequences bring M. cooki together with M. cervicolor and M. caroli in a clade separate from a clade of European species (Chevret et al., 2003). Except for M. musculus, M. cooki is the only species of Mus common to peninsular India and Southeast Asia, but phylogenetic relationships between populations in these two regions have not been critically examined and perhaps more than one species is present in what is now defined as M. cooki . Agrawal (2000), for example, recognized typical cooki with a skull longer than 23 mm, and M. c. nagrum with skull length less than 23 mm. J. T. Marshall, Jr. (1977 b:202) described two size classes in sympatry in NE India and Thailand, but noted "intermediates" from Burma. Significance of this variation requires review by restudy of museum specimens and analyses of DNA sequences from new material. Isolated molars from Thailand caves identified as M. cookii indicate the species has existed in the region since late Pliocene (Chaimanee, 1998).