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Northern Water Rat

Paraleptomys rufilatus

French: Hydromys a flancs roux / German: GroRRe Bergmoosratte / Spanish: Rata de agua deNueva Guinea septentrional

Other common names: Northern Hydromyine, Northern Paraleptomys, Northern Rat

Taxonomy. Paraleptomys rufilatus Osgood, 1945,

“Mount Dafonsero, Cyclops Mountains, northeastern Dutch New Guinea [= Province of Papua, West Papua (= Irian Jaya), New Guinea]. Altitude 4,700 feet [= 1433 m].”

G. G. Musser and M. D. Carleton in 2005 listed Paraleptomys in the Hydromys division (together with Hydromys, Parahydromys, Microhydromys, and Crossomys), and not in the Xeromys division ( Xeromys, Leptomys, and

Pseudohydromys). Molecular studies by K. C. Rowe and colleagues in 2016, however, revealed Paraleptomys as sister to Leptomys, contrary to the former assumed relationship. Further studies are required in order to determine true relationships. P. rufilatus occurs as three disjunct populations, which may represent three distinct species, but hitherto these have not been included in a phylogenetic study, or been studied in detail; further investigation is needed in order to clarify this hypothesis. Monotypic.

Distribution. Cyclops, Princess Alexandra, and Bewani Mts of NC New Guinea.

Descriptive notes. Head—body 118-135 mm, tail 127-146 mm, ear 17-4-20 mm, hindfoot 30-35 mm; weight 54-58 g. The Northern Water Rat is larger than the Short haired Water Rat ( P. wilhelmina) and differs in having a white throat and reddish sides, rather than being uniformly brown. Upperparts are brownish and lateral parts are reddish yellow; top of head is dusky, but sides more reddish. Underparts are grayish brown, but chest and throat are white to the roots. Tail is brownish above and white below. Feet are grayish brown to base of toes, but on innerside they are white. Skull is similar that of the Short-haired Water Rat, but larger, with somewhat smaller bullae; both species also lack the third upper and lower molars. Females have four mammae.

Habitat. Mossy and non-mossy tropical montane forest at 1200-1700 m.

Food and Feeding. Craniodental morphology suggests an insectivorous or worm-eating lifestyle.

Breeding. No information.

Activity patterns. Northern Water Rats are largely nocturnal, but one individual entered a trap during afternoon, suggesting that the species may be partly diurnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Endangered on The IUCN Red List because its area of occupancy is considered to be less than 200 km? and individuals are known from fewer than five locations. There is continuing decline in the extent and quality of its habitat, and hunting has resulted in a continuing decline in the number of mature individuals. It is not known if the Northern Water Rat is present in any protected areas. Further studies of the distribution and ecology of the species are needed.

Bibliography. Boitani et al. (2006), Dickman, Helgen & Wright (2016), Flannery (1995b), Menzies & Dennis (1979), Musser & Carleton (2005), Osgood (1945b), Rowe et al. (2016b), Tate (1951).