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New Guinea Waterside Rat

Parahydromys asper

French: Hydromys rugueux / German: Bergschwimmratte / Spanish: Rata de ribera de Nueva Guinea

Other common names: Coarse-haired Water Rat, \ Waterside Rat

Taxonomy. Limnomys asper Thomas, 1906,

“Mount Gayata, Richardson Range, British New Guinea [= Central Province, Papua, New Guinea]. Alt. 2000-4000" [= 610- 1219m].”

Parahydromys forms a clade with Hydromys, Leptomys, Xeromys, and Pseudohydromys, being sister to Hydromys . Monotypic.

Distribution. N & C mountains of New Guinea, as well as the Bird’s Head (= Vogelkop) Peninsua and Huon Peninsula.

Descriptive notes. Head-body 210-230 mm, tail 234-275 mm, car 10-5-15 mm, hindfoot 48-8-55 mm; weight 490-590 g. The New Guinea Waterside Rat is a large species of Hydromyslike terrestrial rat. Pelageis relatively short and coarse with thick, woolly underfur. Dorsal pelage is coarsely grizzled gray brown, with longer black-tipped guard hairs and white underfur with a brown tip. Ventral pelage is dull grayish, washed with buff, blending from dorsal pelage on sides, which are more grizzled light brown. Feet are pale brownish dorsally, and hindfeet are long, broad, and partially webbed. Ears are short and rounded, being grayish brown and sparsely furred; vibrissae are numerous and thick, becoming shorter near tip of rostrum. Tail is long (c.113% of head-body length) and brownish black for basal half, being white distally. Skull is short with a short and broad braincase compared with that of Hydromys . The cestode Mathevotaenia niuguiniensis has been recorded from this species. Chromosomal complement is 2n = 48, FN = 52.

Habitat. Stream banks,forests, streamside vegetation, and rural gardens at elevations of 700-2200 m.

Food and Feeding. According to native inhabitants, New Guinea Waterside Rats feed on insects and invertebrates, although contents of the one stomach sampled included earthworms. The dense, short, and thick vibrissae and thick lips are an indication of an unusual feeding method.

Breeding. Litter size is apparently two.

Activity patterns. The New Guinea Waterside Rat is terrestrial, unlike its amphibious relatives within Hydromys . It shelters in burrows or under rocks, generally near streams.

Movements, Home range and Social organization. When disturbed, New Guinea Waterside Rats make a strange buzzing-like humming sound that rises and falls in volume. They have a repulsive decaying odor when captured or freshly dead.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The New Guinea Waterside Rat has a relatively wide distribution and it is probably found in various protected areas.

Bibliography. Aplin (2016r), Beveridge (2008), Flannery (1995b), Musser & Carleton (2005), Steppan & Schenk (2017), Watts & Baverstock (1994a).