187.

Lesser Pencil-tailed Tree Mouse

Chiropodomys pusillus

French: Petite Souris-a-pinceau / German: Kleine Pinselschwanz-Baummaus / Spanish: Raton arboricola de cola de lapiz menor

Other common names: Small Pencil-tailed Tree Mouse

Taxonomy. Chiropodomys pusillus Thomas, 1893,

“Mount Kina Balu [= Kinabalu], 1000 feet [= 305 m],” Sabah, Malaysia .

O. Thomas described taxon pusillus as a distinct species, but it was usually treated as a synonym or subspecies of C. gliroides, most recently by G. G.Musser. More recently, in 2005 Musser and M. D. Carleton advocated treatment of pusillus as a full species on grounds that its variation for most dimensions falls outside the range recorded for all other samples of C. gliroides . This conclusion needsto be tested genetically, comparing Bornean pusillus with samples of gliroides from each of southern Vietnam, Peninsular Malaysia, Sumatra, Java, Bali, and intervening smaller islands. Monotypic.

Distribution. Recorded from Sabah and Sarawak (Malaysia) and S Kalimantan (Indonesia), but probably occurs more widely in Borneo.

Descriptive notes. Head—body 69-77 mm, tail 81-96 mm, ear 11-13 mm, hindfoot 16-17 mm. No specific data are available for body weight. The Lesser Pencil-tailed Tree Mouse is the intermediate-sized of the three Chiropodomys species in Borneo, 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, 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. The most detailed available description is of the holotype, by Thomas—“Furcrisp, close and velvety. General color tawny fawn, head and center of back darker, sides paler, outer sides of arms and legs like back, but the wrists and ankles grayish, a color which also extends upon the metatarsus; fingers and toes white; under surface from chin to anus pure white; no darker markings on the face; ears small, evenly oval, practically naked. Tail a little longer than head-body length combined, uniformly brown above and below, its terminal tuft of hairs of about the same thickness, butless extended and commencing more abruptly than in the allied species.” Thomas regarded the speciesas differing from the Indomalayan Pencil-tailed Tree Mouse ( C. gliroides) in the shortness ofits ears, feet and tail; Musser, with much larger samples from across the range of the latter species, found the tiny sample from Borneo to be the smallest.

Habitat. The few records includeone specimen from 300 m elevation at Korawaringin, Riam, Central Kalimantan, and others from 300 m to 945 m on Mount Kinabalu, Sabah. The likely habitat at these elevations is hill dipterocarp forest, merging with oak ( Quercus, Fagaceae) forest at upper end. On Mount Kinabalu, C. pusillus (reported as gliroides) is found between 300 m and 1220 m.

Food and Feeding. No information.

Breeding. No information.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

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

Bibliography. Ellerman & Morrison-Scott (1951), Gerrie & Kennerley (2016h), Medway (1965), Musser (1979), Musser & Carleton (2005), Nor (2001), Phillipps & Phillipps (2016), Thomas (1893d).