New Britain Water Rat Hydromys neobritannicus (Tate & Archbold, 1935)
Type locality: Bainings Mts, Balayang, Wide Bay, East New Britain, Bismarck Archipelago (Tate & Archbold, 1935) .
Taxonomy: The taxonomic status of this species has remained uncertain for several decades. Ellerman (1941) and Ziegler (1982b) treated it as a synonym of H. chrysogaster while Tate (1951) was of the opinion that it should retain this status until the significance of its diagnostic traits can be assessed in a systematic revision of the large-bodied forms of Hydromys. It was recognized as a New Britain endemic by Flannery and White (1991) which since has been followed by most authors (Flannery, 1995; Musser & Carleton, 2005; Singadan et. all 2008). But the taxonomical position of this species has yet to be satisfactory resolved, we are hopeful that the up-coming revision of the Genus Hydromys will resolve a few questions surrounding this species.
Identification: It is similar in size to H. chrysogaster, but the holotype is differing in its "blackish-brown belly and in having a white band around the tail anterior to the white tip" while the second specimen found by Flannery (1995b) differs from the holotype in "having red belly, and in lacking the tail band".
Distribution: Endemic to Papua New Guinea. There is only documented records from New Britain, Bismarck Archipelago, PNG (Flannery, 1995b; Musser & Carleton, 2005) but may also occur on Umboi, where surveys are needed for confirmation (Singadan et. al 2008). Was for a long time only known from the holotype (adult female; M-99867) collected during the Whitney South Seas Expedition by W.F Coultas on on 4 March 1933. Flannery (1995b) managed to locate a second specimen, sub-adult female, held in the Museum fur Naturkunde (Berlin; ZMB 7960) which was collected on the north coast of New Guinea by E. Hartert on 18 June 1886. While a third specimen, an adult male (M-194380) was collected from the Ais River by Margaret T. Gilliard on 6 February 1959.
Singadan et. al. (2008) mentions that it is known from three specimens, the identity of this third specimen remains unknown to us (unless its a typo?).
Natural History: Apart from the fact that it would appear to be a lowland species associated with streams and rivers like all other Hydromys sp. virtually nothing else is known about this species.
Conservation status: Data Deficient (2009 IUCN Red List). Impossible to make a proper assessment concerning the conservation status of this species as it has not been collected since 1959 and there is hardly any details at all accompanying the known specimens. The distribution pattern remain incomplete with at least two of the known specimens collected from "East New Britain". Dedicated fieldwork would be desirable in lowland sites across the eastern half of the Island, which potentially could yield some very interesting discoveries.