Maxomys whiteheadi (Thomas 1894)

[Chrotomys] whiteheadi Thomas 1894, Ann. Mag. Nat. Hist., ser. 6, 14: 452.

Type Locality: Malaysia, Sabah (N Borneo), Gunung Kinabalu.

Vernacular Names: Whitehead's Sundaic Maxomys.

Synonyms: Maxomys asper (Miller 1900); Maxomys batamanus (Lyon 1907); Maxomys batus (Miller 1911); Maxomys coritzae (Sody 1941); Maxomys klossi (Bonhote 1906); Maxomys mandus (Lyon 1908); Maxomys melanurus (Shamel 1940); Maxomys melinogaster (Cabrera 1920); Maxomys perlutus (Thomas 1911); Maxomys piratae (Chasen 1940); Maxomys subitus (Chasen 1940) .

Distribution: Peninsular Thailand south of Isthmus of Kra, Malay Peninsula, Sumatra, Borneo, and various adjacent islands; absent from Java and Bali; see Corbet and Hill (1992) and Musser et al. (1979).

Conservation: IUCN – Lower Risk (lc).

Discussion: A Sundaic endemic. Ellerman and Morrison-Scott (1951) included whiteheadi in the Sulawesi M. musschenbroekii, but the two are separate species (Chasen, 1940; Medway, 1977; Musser, 1991; Musser et al., 1979; Tate, 1936). Spermatozoal morphology (Breed and Yong, 1986) and data from biochemical, morphological, and cytological studies (Chan et al., 1978, 1979; Yong, 1969) pointed to a close relationship between M. whiteheadi and the Malayan M. inas . Md Nor (1996) documented occurrence of M. whiteheadi on the small islands off the tip of N Sabah. Generally a lowland species on Borneo, it does reach 2100 m on the slopes of Mt Kinabalu (Md Nor, 2001, and references cited therein). Noticeable geographic variation in pelage coloration and aspects of cranial morphology exists among insular samples on the Sunda Shelf, but its significance has yet to be determined. However, phylogenetic analyses of mtDNA cytochrome b sequences by Gorog et al. (2004) identified a clade containing two separate lineages on Borneo and another clade containing samples from Sumatra and the Malay Peninsula. Significance of this pattern is discussed by Gorog et al. (2004) in the context of determining whether these lineages represent deep prePleistocene vicariant events or broad Pleistocene migrations over the Sunda Shelf associated with formation of land bridges and insular isolation with subsequent rising sea level. Reviewed by Corbet and Hill (1992).