Leopoldamys sabanus (Thomas 1887)

[Rattus] sabanus Thomas 1887, Ann. Mag. Nat. Hist., ser. 5, 20: 269.

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

Vernacular Names: Indomalayan Leopoldamys.

Synonyms: Leopoldamys balae (Miller 1903); Leopoldamys bunguranensis (Chasen 1935); Leopoldamys clarae (Miller 1913); Leopoldamys dictatorius (Chasen 1940); Leopoldamys fremens (Miller 1902); Leopoldamys heptneri (Dao 1961); Leopoldamys herberti (Kloss 1916); Leopoldamys insularum (Miller 1913); Leopoldamys lancavensis (Miller 1900); Leopoldamys lucas (Miller 1903); Leopoldamys luta (Miller 1913); Leopoldamys macrourus (Jentink 1879); Leopoldamys mansalaris (Lyon 1916); Leopoldamys masae (Miller 1903); Leopoldamys matthaeus (Miller 1903); Leopoldamys mayapahit (Robinson and Kloss 1919); Leopoldamys nasutus (Lyon 1911); Leopoldamys revertens (Robinson and Kloss 1922); Leopoldamys salanga (Chasen 1940); Leopoldamys stentor (Miller 1913); Leopoldamys strepitans (Miller 1900); Leopoldamys stridens (Miller 1903); Leopoldamys stridulus (Miller 1903); Leopoldamys tapanulius (Lyon 1916); Leopoldamys tersus (Thomas and Wroughton 1909); Leopoldamys tuancus (Lyon 1916); Leopoldamys ululans (Robinson and Kloss 1916); Leopoldamys vociferans (Miller 1900) .

Distribution: SE Bangladesh (Chittagong Hill Tracts, AMNH 251694), Thailand (J. T. Marshall, Jr., 1977 a; Robinson et al., 1995), Vietnam from the north in Tuyên Quang Province to the south in Ninh Thuân Province (Dang et al., 1994; Osgood, 1932; Van Peenen et al., 1969; and four islands off the coast; Kuznetsov, 2000), Laos (Aplin et al., 2003 c; Osgood, 1932; Smith et al., In Press; Van Peenen et al., 1969), S and SW Cambodia (Elephant Mtns, specimens in FMNH; Cardamom Mtns, A. Smith, in litt.), S Burma and most islands in Mergui Arch., Malay Peninsula, Sumatra, Java, Borneo, and smaller islands on the Sunda Shelf except Bali; northern limits unresolved. Range mostly extracted from Musser (1981 c), Corbet and Hill (1992), and study of museum specimens in AMNH, BMNH, FMNH, IEBR, MVZ, MZB, RMBR, RMNH, and USNM.

Conservation: IUCN – Lower Risk (lc).

Discussion: Appreciable morphological variation exists between samples from north and south of Isthmus of Kra, and among insular samples from the Sunda Shelf; systematic revision using a suite of morphological traits and molecular data is required to assess whether variation is characteristic of one or several species (Musser, 1981 b). Recent phylogenetic analyses of mtDNA cytochrome b sequences by Gorog et al. (2004) identified separate lineages, each from Borneo, Sumatra, and the Malay Peninsula forming an unresolved trichotomy, and a Vietnam cluster basal to that trichotomy consisting of a paraphyletic pattern of Vietnamese L. sabanus and L. edwardsi . Gorog et al. (2004) suggested that L. sabanus evolved on the Indochinese mainland and the vicariance patterns revealed by molecular analyses "... likely have their roots in the Pliocene fragmentation of the Sunda block..." rather than widespread dispersal across the late Pleistocene Sunda Shelf and subsequent isolation with increasing sea levels. An early preglacial presence of Leopoldamys in the Indochinese region is supported by late Pliocene to middle Pleistocene fossils (Chaimanee, 1998). Usually found in lowland rainforests, infrequently in montane habitats, but does reach 3100 m on the slopes of Mt. Kinabalu in Sabah (Md Nor, 2001) and 1300 m in some highlands on Malay Peninsula (Yong, 1970). Aspects of ultrastructure of pineal gland morphology described by Pévet and Yadav (1980) in comparative context. The name macrourus has priority over sabanus, but is based on a specimen of uncertain origin (Musser, 1981 b).