Rattus colletti (Thomas, 1904) . Novit. Zool., 11:599.

TYPE LOCALITY: Australia, Northern Territory, South Alligator River .

DISTRIBUTION: Australia; known only from the coastal floodplains of the Northern Territory, the most restricted range of all the native Australian Rattus . (see map in Watts and Aslin, 1981).

COMMENTS: Arranged as a subspecies of R. sordidus by Taylor and Horner (1973), but subsequently treated as a separate species (Mahoney and Richardson, 1988; Watts and Aslin, 1981). Although diploid counts are very different, Rattus colletti (2N=42) is genically close to R. villosissimus (2N=50); the two hybridize in the laboratory, but the offspring exhibit severely reduced fertility (Baverstock et al., 1983a, 1986). Fertile hybrids have been obtained between laboratory crosses of R. colletti and R. tunneyi, but the two are sympatric in the wild where no hybrids have been found (Baverstock et al., 1983a).