Systematics and chromosomes of New Guinea Rattus

Abstract

Karyotypes of six endemic New Guinea Rattus species are described. They fall into two distinct types. The R. leucopus group, which is a compact group morphologically, have very similar karyotypes of 32 or 34 chromosomes and are distinct from the Australian Rattus. The karyotypes of the second type, the R. sordidus group, are related to Australian members of the same group. What has previously been regarded as a single species of the sordidus group, R. sordidus gestroi, is shown to consist of two distinct populations with different karyotypes and skull parameters; we consider that they should be regarded as two species.