Microhydromys musseri n. sp., a New Murid (Mammalia) from the Torricelli Mountains. Papua New Guinea T. F. Flannery Flannery, T. F. Microhydromys musseri n. sp., a new murid (Mammalia) from the Torricelli Mountains, Papua New Guinea. Proc. Linn. Soc. N.S.W. Ill (3), 1989: 215-222. Microhydromys musseri n. sp. differs greatly from the only previously described species of Microhydromys {M. richardsoni) in its larger size, brown dorsum with a markedly contrasting venter, broader skull, palate morphology, and dentition details. Both species however share synapomorphies not seen in other hydromyine murids. Micro-hydromys musseri n. sp. is thus far known from a single specimen collected near the summit of Mt Somoro, Torricelli Mountains (part of the North Coast Ranges). It is the third mammal species endemic to these ranges to be described. Three additional speci-mens of Microhydromys richardsoni, which was previously known only from the holotype, are described. These add significantly to knowledge of the species distribution and morphology. T. F Flannery, Australian Museum, Sydney, Australia 2000; manuscript received 31 January 1989, accepted for publication 19 April 1989. KEY WORDS: Microhydromys musseri, New Guinea, Hydromyinae, zoogeography. Introduction The murid subfamily Hydromyinae consists of 10 genera in the Australo-Papuan region. Thomas (1898) and Misonne (1969) have referred Asian taxa to the Hydro-myinae, but Musser (1982) notes that it is not yet clear if any of these taxa do indeed represent part of the hydromyine radiation. All of the Asian taxa are readily distinguish-able from members of the Australo-Papuan group and none resemble the species of Microhydromys. For this reason, and because of their uncertain status, I have restricted comparisons of the new species to Australo-Papuan taxa. Within the New Guinean Hydromyinae are a group of six species, placed in four genera, that are known as microhydromyines. They are small, shrew-like murids with short, sleek coats, tiny eyes and pointed snouts. Included are some of the rarest and least known Melanesian mammals. The genera Mayermys and Neohydromys are monotypic, while Pseudohydromys includes two similar, probably parapatric species. Microhydromys includes two species that differ greatly in morphology, one of which is described here as new. Previous taxonomic work upon microhydromyines has been limited, and it is not yet clear whether these species represent a monophyletic group, or are simply pheneti-cally similar and paraphyletic. Likewise, the generic limits are in some cases poorly understood, and it is possible that in future some genera will be synonymized. Microhydromys richardsoni Tate and Archbold, 1941 was described on the basis of a single adult male taken at an altitude of 850m near Bernhard Camp, Idenburg River, Irian Jaya. It is one of the more distinctive microhydromyines, possessing grooved upper incisors and a broad skull with a short rostrum. A brief mention of the existence of an additional specimen (Menzies and Dennis, 1979) constitutes the only other reported occurrence of this species. In this work a new species of Microhydromys, from the North Coast Ranges, is described; descriptions of 3 additional specimens of M. richardsoni are provided. Although the new species is known only from a single specimen its description as a new PROC. LINN. SOC. N.S.W. , 111 (3), 1989
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