759.

Mountain Giant Rat

Sundamys infraluteus

French: Sundamys des montagnes / German: Berg-Sunda-Riesenratte / Spanish: Rata de Sonda de montana Other common names: Mountain Sundamys

Taxonomy. Mus infraluteus Thomas, 1888,

“Mount Kina Balu, North Borneo [= Sa- bah],” Malaysia.

S. infraluteus is the sister species to S. an- nandalei. There are two subspecies recognized, although they probably represent distinct species based on morphological snd genetic data Bionsanipie is needed duis to sithoush prove this phile hypothesis.

Subspecies and Distribution.

S.a.infraluteusThomas,1888—NBorneo .

S. a. atchinus G. S. Miller, 1942 — W Sumatra.

Descriptive notes. Head-body 229-282 mm, tail 289-343 mm, ear 22-29 mm, hindfoot 55-61 mm; weight 468-643 g. The Mountain Giant Ratis a large species of Sundamys similar in size to Bartels’s Rat ( S. maxi). Pelage is soft and relatively long. Dorsal pelage is a dark blackish brown and ventral pelage is a dark gray witha strong orange tinge; ventral pelage is not sharply demarcated from dorsum. Feet are elongated and covered in dark brown fur dorsally. Ears are long and dark and vibrissae are very long, extending beyond the ears. Tail is long (c.120% of head-body length), lightly furred, and uniformly dark brown. There are some morphological differences between the populations on Borneo and Sumatra, such as the Sumatran populations having more robust teeth and deeper, woollier fur. Skull is much larger than those of Annandale’s Sundaic Rat (S. annandaler) and Muiler’s Rat (S. mueller). Ridging of supraorbital and temporal regions is well-marked. Zygomatic plate of zygomatic arch is placed anterior to M'. Zygomatic plate overlaps M' along antero-posterior axis. Reduced tympanic bullae do not overlap squamosal root of zygomatic arch along antero-posterior axis. Spenopterygoid vacuity is closed, with bony wall. Sphenoid and vomer bridge is always present and very visible between mesopterygoid fossa. Molars are large relative to skull length. Cusp t3 is not present orwell developed on M? and M?. There are three pairs of mammae: one post-axillary and two inguinal.

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Habitat. Highland primary montane forest at elevations of 920-2930 m in Borneo and 700-2400 m in Sumatra.

Food and Feeding. Stomach contents included “vegetable matter, apparently shoots, twigs and bark.” One specimen was captured with a crab bait.

Breeding. No information.

Activity patterns. The Mountain Giant Rat is probably nocturnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Aplin (2016aa), Camacho-Sanchez et al. (2017), Cranbrook et al. (2014), Harrison (1954a, 1954b, 1957), Medway (1969), Musser & Newcomb (1983), Nor (2001), Phillipps & Phillipps (2016).