309.

Eastern New Guinea Shrew Mouse

Pseudohydromys murinus

French: Souris-musaraigne orientale / German: Ostliche Moosmaus / Spanish: Raton musarana de Nueva Guinea oriental

Other common names: Eastern Shrew Mouse

Taxonomy. Pseudohydromys murinus Rummler, 1934,

“Morobe, Mt. Misim [= Missim], 7000 Ful} [= feet] [= 2134 m], Nordost-Newguinea [= NE Papua New Guinea] (Brit. N.-G.).»

Pseudohydromys murinus is the type species of the genus. Specimens now referred to P. eleanorae were formerly identified as P. murinus . K. M. Helgen and L. E. Helgen referred both of those species to a murinus species group that also includes P. berniceae . Two morphometrically distinct forms are identified, possibly representing two species: one form occurs in the Owen Stanley Range, Mount Missim and Mount Kaindi, all in eastern Papua New Guinea, and represents typical murinus, the other, currently unnamed form comprises specimens from central Papua New Guinea. A gap of ¢.200 km currently separates the two populations. P. murinus is syntopic through most of its range with P. fuscus and P. ellermani, additionally with P. eleanorae in the far west; in the Owen Stanley Range it issyntopic with P. berniceae and P. germani . Monotypic.

Distribution. Widely distributed in the C & E parts of the Central Range of New Guinea.

Descriptive notes. Head-body 70-105 mm, tail 81-102 mm, ear 9-13 mm, hindfoot 18-22 mm; weight 15-19-9 g. Pseudohydromys is a taxonomically diverse group of smallbodied 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; tail narrow and thinly furred, 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 murinus species group have two molars per quadrant, relatively unreduced in size compared with members of other species groups; they also share a suite of special cranial features. The Eastern New Guinea Shrew Mouse is among the smaller members of genus; fur is short and velvety, dark brownish gray on upperparts but usually with pale flecking on back and rump, slightly paler below, with no contrasting markings on head; vibrissae fine and elongate, extending well past ears; eyes very small; ears small and dark gray; upper surfaces of forefeet white;upper surfaces of hindfeet pigmented and with dark gray hairs except for digits, which are white; tail (averages 102% of head-body length) is dark for most of length, but sometimes with pale mottling orvery short white tip. Spermatozoa with head 8-5 pm long and 3 pm wide, with apical hook and two accessory ventral hooks,tail 107 pm.

Habitat. All records are from evergreen tropical montane rainforests, ranging from lower montane rainforest between c.1500 m and ¢.2500 m, and upper montane rainforest above ¢.2500 m, to the tree line, where Eastern New Guinea Shrew Mice have been taken in elfin mossy forest bordering subalpine grassland at elevations of ¢.3400 m.

Food and Feeding. A study of the diet of the Eastern New Guinea Shrew Mouse and two congeners in Morobe Province, as reflected by gut contents, found this species to be primarily insectivorous, eating less plant tissue and more oligochaete worms than did Shaw Mayer’s Shrew Mouse ( P. ellermani) and the Mottled-tailed Shrew Mouse (FP. fuscus).

Breeding. The low mammary formula (two pairs) indicates a small litter size. One specimen captured at Mount Kaindi, Morobe Province, in October 1962 was pregnant, with asingle embryo.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The lower part of the elevational range in the central cordillera of Papua New Guinea coincides with a zone of extensive habitat modification caused by long-term subsistence agricultural activities. Habitats above 2500 m are much less affected by subsistence activities, but, in places within the range of the Eastern New Guinea Shrew Mouse, are potentially impacted by large-scale resource-development projects.

Bibliography. Breed & Aplin (1995), Ellerman (1941), Flannery (1995b), Helgen & Helgen (2009), Helgen, Singadan et al. (2016), Jackson & Woolley (1993), Laurie (1952), Menzies & Dennis (1979), Musser & Carleton (1993, 2005), Rummler (1934, 1938), Tate (1951).