Type locality: Sirinumu Dam (550m), Sogeri Plateau, Central Province, Papua New Guinea (Helgen, Leary & Helgen, 2010).
Size and identification:
Distribution: This species has been recorded from three localities along the southern slopes of the Central Cordillera in south-central Papua New Guinea: southern slopes of Mt. Sisa (1450m), Southern Highlands Province; adult female (AM M1416) collected 18 September 1979 by D. Dwyer; 10km north-east of the village Faia (380m), Darai Plateau, Gulf Province; adult male (UPNG 4310) collected 26 July 2003 by T. Leary and P. Pennay; Sirinumu Dam (550m), Sogeri Plateau, Central Province; adult male (BBM-NG 60202) collected 28 October 1968 by M. Nadchatram.
Though, members of this Genus is rarely trapped and available captures indicate that it is likely to be widespread in hill forest and lower montane habitats along the southern margin of the Central Cordillera. At the moment regarded to be an PNG endemic; though maybe to be expected in the Papuan Province (Indonesia) as well.
Natural History: The holotype of M. argenteus (BBM-NG 60202) was trapped in "secondary forest-eucalyptus savannah" on the Sogeri Plateau, an indication that it isn't confined to mature forest formations (Flannery, 1995a). While the female specimen (AM M1416) was trapped in an Elliott/Sherman trap baited with sweet potato in a locality described as "primary forest with some trees fall dating from a storm two years before" (Dwyer, 1990); with a total of 80 traps set per night between February 1979 and February 1980 but no other moss-mice was collected at this locality, which was re-visited by K. Aplin in 1985 but who failed to trap any Microhydromys. The third and last specimen (UPNG 4310), was caught in an Elliott trap baited with canned fish in primary forest on the Darai Plateau. Nothing is known regarding reproduction.
Conservation status: Not evaluated yet. The most appropriate category would probably be Data Deficient; so far it has proven to have been rarely collected/overlooked (?) but widespread south of the Central Cordillera and given the current knowledge concerning the distribution it is highly unlikely to be threatened.