227. Mountain Water Rat Baiyankamys habbema

French: Rat de |' Habbema / German: Habbema-Schwimmratte / Spanish: Rata de agua montana Other common names: Mountain Baiyankamys, New Guinea Mountain Water Rat

Taxonomy. Hydromys habbema Tate & Archbold, 1941,

“Lake Habbema, 15 km N Mt Wilhelmina, Netherlands New Guinea” 24 km N of Gunung Trikora, 3225 m, Pengunungan Maoke, Papua Province, Indonesia).

Baiyankamys habbema was originally described as a species of Hydromys, and earlier thought to occur also incentral mountains of Papua New Guinea. Eastern populations recently distinguished at species level, and the two taxa separated generically from Hydromys . Monotypic.

Distribution. Recorded as living animal from the vicinity of Lake Habbema (3225 m) and an area close to Mt Trikora, WC New Guinea. Late Quaternary subfossils reported (as Hydromys habbema) from Kelangurr Cave and from alluvial terrace of West Baliem River, at 280-2950 m,Papua Province. Tentative record of habbema from a fissure deposit at 3450 m on Mt Jaya requires confirmation.

Descriptive notes. Head-body 134-160 mm, tail 154-187 mm, ear 7-9 mm, hindfoot 35-39 mm. No specific data are available for body weight. Baiyankamys species are plump, shortlimbed, semi-amphibious murines with broad head, moderately long snout with numerous long, fine vibrissae, short rounded ears; fur on upperparts very soft, dense, underside paler; hindfeet proportionally large and broad, with partial webbing between toes;tail longer than head-body length, thickly furred, dark basally and with white tip. Dentition is characterized by delicate incisors, loss of third molars, and basined molar morphology. The Mountain Water Rat has a longer white portion on tail (one third to half of length), more reduced ears (less than 10 mm), and silverygray underparts. Molar teeth are slightly larger than those of Shaw Mayer’s Water Rat ( B. shawmayeri). Mammae two on each side, both inguinal.

Habitat. Waterbodies and streams within mountainous landscape above 3200 m that regionally supports upper montane tropical forest.

Food and Feeding. No information.

Breeding..ow mammary formula (two pairs) indicates a small littersize.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. There is little anthropogenic disturbance at the high elevations at which this species occurs.

Bibliography. Flannery (1995b, 1999), Helgen (2005), Hope (1976), Leary, Singadan, Menzies, Helgen, Allison et al. (2008a), Musser & Carleton (2005), Musser & Piik (1982), Tate (1951), Tate & Archbold (1941).