Mylomys dybowskii (Pousargues, 1893) . Bull. Soc. Zool. Fr., 18:163.

TYPE LOCALITY: Central African Republic (= French Congo), Kemo River .

DISTRIBUTION: Guinea (Mt Nimba), Ivory Coast, Ghana, S Cameroon, Congo, Central African Republic, W, N and E Zaire, Rwanda, Tanzania, Kenya, Uganda, and S Sudan.

SYNONYMS: alberti, christyi, cuninghamei, lowei, massaicus, rex, richardi, roosevelti .

COMMENTS: Hatt (1940a) noted that the cotypes of dybowskii are examples of Mylomys and not Pelomys, under which the name had been listed (Ellerman, 1941), and selected a lectotype. The identity was verified by F. Petter (1962b). Significance of geographic variation in chromatic and morphological traits has yet to be assessed by critical systematic revision; whether the genus is monotypic or contains more than one species is unresolved. Chromosomal data for sample from Central African Republic reported by Matthey (1970), and those from Mt Nimba (Guinea) provided by Gautun et al. (1986).

The taxon rex, represented only by the holotype, a skin without skull from Kaffa in C Ethiopia, was described by Thomas (1906a) as a species of Arvicanthis, but later "provisionally considered as a giant member of Desmomys " (Thomas, 1916a:68). Dieterlen (1974) challenged the validity of rex, but Yalden et al. (1976) pointed out the features distinguishing the holotype from samples of D. harringtoni, and treated rex as another distinctive species endemic to Ethiopia. Our study of the holotype skin reveals it to be a large and probably old adult of Mylomys that is not as brightly pigmented as most samples of that genus. Whether the holotype actually came from Ethiopia, or represents a separate species of Mylomys are unknown; we provisionally list rex in the synonymy of M. dybowskii .