Arvicanthis abyssinicus (Riippell, 1842) . Mus. Senckenberg., 3:104.

TYPE LOCALITY: Ethiopia, Simien Prov., Simien Mtns, Entschetqab (see Osgood, 1936:252) .

DISTRIBUTION: Ethiopia, between 1300-3400 m (Yalden et al., 1976).

SYNONYMS: fluvicinctus, rufodorsalis, saturatus .

COMMENTS: An Ethiopian endemic and morphologically distinctive species whose closest relative is A. blicki, another Ethiopian endemic. Historically the species was perceived to embrace forms occurring from Ethiopia south to Zambia (Allen, 1939; Dollman, 1911; Ellerman, 1941), but Osgood (1936:252) discussed several of abyssinicus's diagnostic features, noting that it "is not unlikely that it is confined to Ethiopia and at least some of the forms of Kenya and Uganda which have been associated with it will need other allocation." This view has been reinforced by morphometric analyses (Rousseau, 1983), and our examination of specimens.

Arvicanthis abyssinicus and A. blicki are the only species of Arvicanthis endemic to Ethiopia, both are part of middle and high altitude grassland and moorland endemic mammal faunas of Ethiopia (Demeter and Topal, 1982; Rupp, 1980; Yalden, 1988), and both are more closely related to each other than to any other species of the genus. Arvicanthis niloticus and A. somalicus also occur in Ethiopia (see those accounts), but their ranges also extend far beyond that country's boundaries.

Rousseau (1983) regarded mearnsi, described as a subspecies of A. abyssinicus by Frick (1914), to also be a subspecies of A. abyssinicus, but its qualitative dental and chromatic characteristics fall within the range of variation seen in A. niloticus, as Osgood (1936) and Yalden et al. (1976) noted (discussed by them under either lacernatus or dembeensis).

Chromosomal data reported by Orlov et al. (1992) within the context of studying chromosomal variation among Ethiopian samples of Arvicanthis.