A chromosomal and morphometric study of Papuan tree rats Pogonomys and Chiruromys (Rodentia, Muridae)



Material representing the nine currently recognized species of Pogonomys and its subgenus Chiruromys was subjected to a programme of canonical correlation analysis. Results indicated that six of these species were distinct while two other groups merited subspecific rank. The holotype of another species, P. mollipilosus, appeared to bear little relation to the widespread montane rats with which it has customarily been associated and is now included in the synonomy of a lowland species, P. macrourus. Computer analysis did not suggest any close relationship between Chiruromys and Pogonomys and Chiruromys is now regarded as a separate genus. Examination of the chromosomes confirms that the division into two genera is valid and, while the karyotype of one could be derived from the other it could just as easily be derived from an independent ancestor. Therefore we postulate an independent origin for Chiruromys and Pogonomys.