Pseudohydromys occidentalis Tate 1951

311.

Western New Guinea Shrew Mouse

Pseudohydromys occidentalis

French: Souris-musaraigne occidentale / German: Westliche Moosmaus / Spanish: Raton musarana de Nueva Guinea occidental

Other common names: Western Shrew Mouse

Taxonomy. Pseudohydromys occidentalis Tate, 1951,

“Lake Habbema, north of Mt. Wilhelmina, [Snow Mountains], Netherlands New Guinea, 3225 meters.”

Pseudohydromys occidentalis was referred by K. M. Helgen and L. E.Helgen to an occidentalis species group that also includes P. musseri and P. sandrae. Some prior records of P. occidentalis in Papua New Guinea are based on specimens of Mirzamys louiseae, which was named in 2009 to accommodate these samples; other incorrect records derived from misidentification of examples of P. fuscus. Syntopic or nearly so in the Snow (= Sudirman) Mountains with P. ellermaniand P. patriciae. Syntopic in the Star (=Jayawijaya) Mountains with P. ellermani. Monotypic.

Distribution. Known only from two widely separated areas of W & C New Guinea (Lake Habbema and Mt Trikora in the Snow Mts, and the Star Mts).

Descriptive notes. Head-body 87-115 mm, tail 85-95 mm, ear 8-12 mm, hindfoot 19-21-5 mm. No specific data are available for body weight. Pseudohydromys is a taxonomically diverse group of small-bodied murines characterized by dense, velvety to plush fur; a variably narrowed and flattened head with small eyes and ears; head generally without contrasting pattern; vibrissae fine and elongate, extending past ears; eyes small to minute; narrow hindfeet, lacking webbing between digits and with claws on all digits; narrow and thinly furred tail, approximating to combined length of head and body; mammae (when known) two on each side, both inguinal; cranium delicately built, with small molars reduced in number to two or fewer per quadrant. Members of the occidentalis species group have relatively shorttail, two very reduced molars per quadrant, a short rostrum, and other special cranial features. The Western New Guinea Shrew Mouseis one of the larger members of genus; fur is dense and relatively thick (c.8 mm on back), dark brownishgray on upperparts and paler gray below, with no contrasting markings on head; vibrissae fine and elongate, extending just past ears; eyes very small; ears small and pale, with fine dark hairs; upper surfaces of forefeet white; upper surfaces of hindfeet weakly pigmented and with white hairs; tail (averages 90% of head-body length) relatively pale, with silvery hairs and lacking a white tip.

Habitat. The few capture localities are situated in broad tracts of evergreen, mid-montane to upper montane tropical forests. Recorded in the Snow Mountains at elevations of 3325 m and at least 3800 m, close to the tree-line; in the Star Mountains at 2300-2600 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 List. The most recent records from the Snow Mountains are from as far back as 1938, while the two specimens from the Star Mountains were both collected more than 30years ago. In both areas, the habitat of the Western New Guinea Shrew Mouse is above the elevational limits of traditional subsistence agriculture. Its habitat is, however, vulnerable to the impacts of drought and anthropogenic firing, and is proximal to regional resourcedevelopment projects.

Bibliography. Gerrie & Kennerley (2016n), Flannery (1995b), Helgen & Helgen (2009), Jackson & Woolley (1993), Menzies & Dennis (1979), Musser & Carleton (1993, 2005), Tate (1951).