Rattus macleari Thomas 1887

Rattus macleari Thomas 1887, Proc. Zool. Soc. Lond., 1887: 513.

Type Locality: Christmas Isl (Australia).

Vernacular Names: Maclear's Christmas Island Rat.

Distribution: Endemic to Christmas Isl, 320 km south of Java in the Indian Ocean; thought to be extinct by 1908 (Andrews, 1909) and now considered extirpated (Flannery, 1990 c), with time of extinction between 1901 and 1904 (Pickering and Norris, 1996).

Conservation: IUCN – Extinct.

Discussion: Rattus species group unresolved. Ellerman (1941) first listed the species as the only member of " macleari " group in subgenus Rattus, then placed it and R. nativitatis in same group within subgenus Stenomys of Rattus (Ellerman, 1949 a) . Chasen (1940) thought R. macleari to be nearest Sundamys muelleri, but in their comparisons, Musser and Newcomb (1983) found no support for this alliance. Misonne (1969) included R. macleari in subgenus Rattus; at the other extreme, Sody (1941) proposed genus Christomys to contain it. In the original description, Thomas (1887 c) indicated R. macleari belonged to a group that included Taeromys celebensis, Lenomys meyeri, Rattus everetti, and R. xanthurus (he treated all as Rattus); of these, only R. xanthurus resembles R. macleari (Musser and Newcomb, 1983) . Phylogenetic relationships remain unresolved, but Musser (1986) suggested R. macleari should be compared with a group of species that includes R. annandalei, R. enganus, R. korinchi, R. montanus, R. nativitatis, and R. xanthurus, none of them members of subgenus Rattus but distantly related to it.

Until the introduction of Rattus rattus in 1899 (apparently from a cargo of hay carried by the S. S. Hindustan; Pickering and Norris, 1996), R. macleari and R. nativitatis were the only rats living on Christmas Isl. The possible role of disease transferred from R. rattus to R. macleari in abetting its extinction is discussed by Pickering and Norris (1996), who also identified specimens with color patterns they interpreted to reflect hybridization between the introduced species and R. macleari . All specimens, however, can be identified as either R. rattus or R. macleari and provide no evidence of hybridization (Musser and Norris, ms.), which is consistent with the distant phyletic relationship between the two as assessed by morphological traits. Whatever the causes of extinction (and introduced infectious diseases may have played a role) hybridization was not one of them.