Rattus nativitatis (Thomas, 1889) . Proc. Zool. Soc. Lond., 1888:533 [1889].

TYPE LOCALITY: Christmas Isl (Australia) .

DISTRIBUTION: Endemic to Christmas Isl, 320 km south of Java in the Indian Ocean; suspected to be extinct by 1908 (Andrews, 1909) and is now considered extinct (Flannery, 1990c).

COMMENTS: For Thomas (1888b), the morphology of R. nativitatis distanced it from any other described species of Rattus . Ellerman (1941) first listed the species as the only member of the " nativitatis " group in subgenus Rattus, then placed it and R. macleari in same group within subgenus Stenomys of Rattus (Ellerman, 1949a) . Chasen (1940) thought R. nativitatis to be without close relatives in Malaysia, but Misonne (1969) placed it close to rajah in the subgenus Leopoldamys of Rattus, an allocation rejected by Musser (1981 b) and Musser and Newcomb (1983). Three hypotheses about phylogenetic position of R. nativitatis require testing: 1. It is more closely related to R. macleari, the other endemic on Christmas Island than to any other species of Rattus; 2. It is not related to R. macleari but to other species in the genus or is phylogenetically isolated; 3. It is not even a member of Rattus.