185.

Greater Pencil-tailed Tree Mouse

Chiropodomys major

French: Grande Souris-a-pinceau / German: Grol 3e Pinselschwanz-Baummaus / Spanish: Raton arboricola de cola de lapiz mayor

Other common names: Large Pencil-tailed Tree Mouse, Large Sunda Tree Mouse

Taxonomy. Chiropodomys major Thomas, 1893,

“Sadong, Sarawak,” Malaysia. Morphological features align C. major with C. calamianensis of Palawan and nearby islands. Type locality of major is in southern Sarawak. Two other named forms currently linked to C. majorare legatus and pictor, both described by O. Thomas in 1911 and both from Mount Kinabalu, in Sabah. Although pictor was associated with C. gliroides by|. R. Ellerman and T. C. S. Morrison-Scott in 1951, the identity of both with C. major was posited by Lord Medway and supported by G. G.Musser. Monotypic.

Distribution. Borneo, where currently recorded only from Sarawak and Sabah (Malaysia), but probably found also in Kalimantan (Indonesia).

Descriptive notes. Head—body 94-114 mm, tail 109-144 mm, ear 13-27 mm, hindfoot 21-28 mm; weight 32-43 g. Some evidence for weak, male-biased sexual dimorphism in length and body weight. The largest of the three Borneo species of Chiropodomys, with typical body form for this arboreal genus—short head with large eyes, moderately large, thinly furred ears, and elongate, narrow vibrissae that, folded back, extend up to halfway along length of body; slender body clothed in short, soft and dense fur with inconspicuous scattered guard hairs; short, broad hindfoot with nailed hallux and short, recurved claws on second to fourth digits; and elongate, well-furred tail with distinct brush or terminal tuft. Coloration of the Greater Pencil-tailed Tree Mouse features grayish-brown or grayish-tawny fur on dorsum, grayerflanks, and usually white or cream (less often pale buffy-white) venter. Venter is always sharply delimited from flanks, but there is no intervening buffy strip. Cheeks are usually white, less commonly gray. Ears are dark brown. Foreand hindfeet proportionally larger than in some species of Chiropodomys, though less so than those of Koopman’s Pencil-tailed Tree Mouse ( C. karlkoopmani). Forefeet are white; hindfeet also white, except for strip of brown hairs down midline from ankle to base of digits. Tail,slightly shorter relative to headbody length than in other members of genus, is uniformly dark, with brown-pigmented scales and fine brown hairs, or irregularly bicolored, with patches of white or cream skin and hairs along ventral surface. Two mammae on each side, both inguinal. Skull is distinguishable from those of congeners by combination oflarge size,relatively gracile incisors, less reduced molars, and moderately large auditory bullae.

Habitat. Currently known only from tropical forest habitats, including lowland forest in Sarawak and Sabah, and lower montane forest between 900 m and 1500 m on Mount Kinabalu, Sabah. Other species of genus persist following conversion of primary/secondary forests to plantations and gardens, but whether this is true also for the Greater Pencil-tailed Tree Mouse is not known.

Food and Feeding. Greater Pencil-tailed Tree Mice are presumably mainly herbivorous.

Breeding. Four individuals tracked by the line-and-spool method in primary rainforest at 800-900 m in Sabah entered refuges in diverse positions: one in a tree hollow c.4 m above ground, one in a den c¢.5 m aboveground in stump of a dead tree, and two in holes near tree roots and a log.

Activity patterns. Study of activity patterns in primary rainforest at 800-900 m in Sabah documented a highly arboreal lifestyle, but with regular excursions on to ground. Scheduling was not examined, but most individuals were trapped at night.

Movements, Home range and Social organization. Largest recorded movement was of 113 m between capturesites. Estimates home ranges for frequently captured individuals (presumed residents) varied from 1600 m? to 4600 m? for males and 200 m? to 2600 m” for females. Ranges were overlapping, both within and between sexes, with each individual likely to encounter several others of each sex within its range.

Status and Conservation. Classified as Data Deficient on The IUCN Red List.

Bibliography. Ellerman & Morrison-Scott (1951), Lunde, Ruedas & Helgen (2008), Medway (1965), Musser (1979), Payne et al. (1985), Thomas (1893d, 1911f), Wells et al. (2004).