Arborimus Taylor, 1915 . Proc. California Acad. Sci., ser. 4, 5:119.

TYPE SPECIES: Phenacomys longicaudus True, 1890 .

SYNONYMS: Paraphenacomys .

COMMENTS: Described as a subgenus of Phenacomys and conventionally recognized as such or as a complete synonym (Carleton and Musser, 1984; Hall, 1981; Howell, 1926b). Evidence for generic stature marshalled by Johnson (1968, 1973). Nonetheless, whether Arborimus is most closely related to Phenacomys or to some other arvicoline has not been substantiated with broad taxonomic sampling that includes critical species like albipes . Specific and subspecific classification basically set forth by Howell (1926b) and Hall and Cockrum (1953), as part of Phenacomys, and by Johnson and George (1991).