Core of B. chrysocomus Group. Placed in a "Rattus chrysocomus Group" (Tate, 1936), in subgenus Rattus (Ellerman, 1941), then subgenus Maxomys of Rattus (Ellerman 1949a: Laurie and Hill, 1954, but later treated as a Bunomys (Musser, 1981c, 1991; Musser and Newcomb, 1983; Musser and Carleton, 1993); Corbet and Hill, 1992). Chromosomes described by Duncan (1976) and karyotypic data summarized and compared with other murines by Rickart and Musser (1993).

On the NE peninsula, B. chrysocomus is sympatric with B. fratrorum; in the central core of the island it is broadly sympatric with an undescribed species at middle altitudes and marginally sympatric with B. andrewsi at low elevations and B. penitus in montane forest. No extant specimens of B. chrysocomus have been collected from lowlands of the SW peninsula, partly because most of the original forest has been removed and partly because the remaining tracts have not been adequately surveyed, but the species once occurred in the deforested areas as represented by subfossils (Musser, ms).