306.

Shaw Mayer’s Shrew Mouse

Pseudohydromys ellermani

French: Souris-musaraigne d'Ellerman / German: Shaw-MayerMoosmaus / Spanish: Raton musarana de Shaw Mayer

Other common names: One-toothed Shrew Mouse

Taxonomy. Mayermys ellermani Laurie & Hill, 1954,

“Northern slopes of Mt Wilhelm, Bismarck Range, North-East [Papua] New Guinea, 8000 ft [= 2438 m].”

Pseudohydromys ellermani was originally described as a new genus and species, and was maintained as such until 2009, when K. M. Helgen and L. E.Helgen argued for a more inclusive definition of Pseudohydromys; Helgen and Helgen referred it to an ellermani species group that also includes

P. carlae, P. germani, and P. pumehanae . Two morphometrically distinct forms are identified, possibly representing different species. One form occurs in the eastern and central highlands of Papua New Guinea, west to the Star (=Jayawijaya) Mountains, and represents typical ellermani; the other, currently unnamed, comprises specimens from the Snow (= Sudirman) Mountains of Papua Province, Indonesia; agap of ¢.300 km currently separates the two populations. Prior records from the Owen Stanley and Maneau Ranges of south-eastern Papua New Guinea are now allocated to P. german . In the Snow Mountains P. ellermani is syntopic with P. patriciaeand P. occidentalis; in the Star Mountains with P. occidentalis, on Mount Wilhelm with P. eleanorae, P. fuscus, and P. murinus, and elsewhere in eastern New Guinea with P. fuscus and P. murinus . Monotypic.

Distribution. Recorded from the Central Range of New Guinea, including the Snow Mts of Papua Province, Indonesia, and numerous localities between the Star Mts and Mt Missim in Papua New Guinea.

Descriptive notes. Head-body 85-103 mm, tail 90-113 mm, ear 10-12 mm, hindfoot 19-23 mm; weight 13-21 g. 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; 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 ellermani species group have one small molar per quadrant, forward-projecting upper incisors, fur smoky gray above and below with no grizzling or white spotting on rump, and vibrissae extending just past ears; they also share a suite of other unique cranial features. Shaw Mayer’s Shrew Mouse is a medium-sized member of genus; fur is velvety, smoky gray on upperparts, slightly paler below, and occasionally with white patches on midline of chest or abdomen; ears small and pale gray; upper surfaces of feet pale gray, with short buff or whitehairs; tail (averages 106% of head—body length) is mostly brown but usually mottled and with short white tip, distinctly hairy, with tail hairs equal to 1-5-tail scales. Note that published account of spermatozoa is based on specimens from Mount Karimui now tentatively referred to the Southern Small-toothed Moss Mouse ( P. pumehanae).

Habitat. All captures have been made in evergreen tropical montane rainforest, including both lower montane rainforests and mid-montane rainforests, at elevations of 1400-2800 m; mostrecords are from above 1900 m. Unlike most congeners, Shaw Meyer’s Shrew Mouse does not extend upwards into upper montane rainforests that are present across its geographic range.

Food and Feeding. A study in Morobe Province of the diet of Shaw Mayer's Shrew Mouse and of two congeners, the Mottled-tailed Shrew Mouse (FP. fuscus) and the Eastern New Guinea Shrew Mouse ( P. murinus), as reflected by gut contents, found this species to be primarily insectivorous, but eating fewer lepidopterans and more plant material than the other two species, and with no evidence for consumption of oligochaete worms.

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

Activity patterns. All captures have been made either on the ground or on fallen logs.

Movements, Home range and Social organization. The sample of specimens in museum collectionsis heavily biased toward males, unlike samples of congeners, and this may indicate some contrast in the pattern of movements.

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 resulting from long-term subsistence agricultural activities. Habitats above 2500 m are much less affected by subsistence activities but, in places within the range of Shaw Mayer’s Shrew Mouse, are potentially impacted by large-scale resource-development projects. Although this species is widespread and better represented in collections than most others of the genus, it appears to be nowhere common.

Bibliography. Donnellan (1989), Flannery (1995b), Helgen (2005), Helgen & Helgen (2009), Helgen et al. (2008b), Jackson & Woolley (1993), Laurie & Hill (1954), Lidicker (1968), Lidicker & Ziegler (1968), Menzies & Dennis (1979), Musser & Carleton (1993, 2005).