278.

Southern Groove-toothed Shrew Mouse

Microhydromys argenteus

French: Hydromys argenté / German: Stdliche Kleinwassermaus / Spanish: Raton musarana de dientes estriados meridional

Taxonomy. Microhydromys argenteus K. M. Helgen, Leary & Aplin, 2010,

“Sirinumu Dam, 550 m, Sogeri Plateau, Central Province, Papua New Guinea.”

Prior to 2010, specimens of M. argenteus were referred to M. richardsoni . Monotypic.

Distribution. Known only from three localities in S foothills of Central Cordillera of E New Guinea.

Descriptive notes. Head-body 78-86 mm, tail 71-83 mm, ear 11:4-12 mm, hindfoot 19-22 mm; weight 12-13 g. Microhydromys species are tiny murines with short, velvety fur that is gray to brown on upperparts and slightly paler below; head with very reduced eyes, long,fine vibrissae, and moderately large ears; all feet with claws on all digits, hindfeet narrow and with small plantar pads; tail approximately equal to combined length of head and body, thinly furred, all dark or with short white tip. Cranium with short rostrum, proportionally small molars, and proportionally large auditory bullae. Dentition is characterized by longitudinally grooved upper incisors,loss of third molars, and basined molar morphology. Distinguishing features of the Southern Groove-toothed Shrew Mouse compared with Northern Groove-toothed Shrew Mouse ( M. richardsoni) are that it has tail shorter than head-body length, distal half white; upperparts paler gray brown and underside only slightly paler; hindfeet slightly longer and clothed in white hairs; ears slightly larger and paler. Mammae two on each side, both inguinal.

Habitat. Forest, at elevations of 380-1450 m.The three known localities are in contrasting habitats: “secondary forest-Eucalypt savannah” on the Sogeri Plateau; primary evergreen hill forest on limestone karst on the Darai Plateau; and lower montane forest with minor anthropogenic disturbance at Mount Sisa.

Food and Feeding. No information.

Breeding. Low mammary formula (two pairs) indicates a small litter size.

Activity patterns. Body proportions indicate terrestrial lifestyle, while somber coloration and small eyes suggest nocturnal and possibly semi-fossoriallifestyle.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. Despite evidence of habitat flexibility, the Southern Groove-toothed Shrew Mouse appears to be nowhere common and its distribution may be fragmented. Relevant observations include repeated failure to obtain images of the species during camera-trapping surveys at many sites within its known range, and absence of its remains in several large owl pellet collections from cavesat elevations of 100-500 m in the Purari River catchment, Gulf Province, and 500-1000 m in headwaters of the Fly River, Western Province, all in habitats similar to those on the Darai Plateau.

Bibliography. Dwyer (1984), Flannery (1989, 1995b), Helgen & Helgen (2009), Helgen et al. (2010), Jackson & Woolley (1993), Kennerley & Gerrie (2016), Leary & Seri (1997), Musser & Carleton (2005), Tate (1951).