Arvicanthis somalicus Thomas, 1903 . Proc. Zool. Soc. Lond., 1902(2):312 [1903].

TYPE LOCALITY: Northern Somaliland (Somalia), Shuk, 4000 ft .

DISTRIBUTION: N and E Rift Valleys of Ethiopia (Yalden et al., 1976), Somalia, extreme SE Sudan (Dieterlen and Nikolaus, 1985), and south through Kenya in and east of the Rift Valley (Dollman, 1911; Hollister, 1919) to C and EC Tanzania on both sides of the Rift; limits have yet to be resolved.

SYNONYMS: neumanni, reptans, rumruti.

COMMENTS: From the time it was described by Thomas (1903 «), A. somalicus has been treated as a species (Allen, 1939; Dollman, 1911; Ellerman, 1941; Hollister, 1919), and with an exception or two (e.g., Misonne, 1974), retains that status (Rousseau, 1983; Yalden et al., 1976). Both reliable published records (see above) and specimens we examined document the northern and central range of A. somalicus . Known southern limits of the species are defined by samples from the Mawele region south of Tabora (Mwanasomano's, 31 mi S Tabora) in C Tanzania and southeast of there at Kilosa in EC Tanzania (specimens in Museum of Comparative Zoology, Harvard). The species is sympatric with both A. niloticus and A. nairobae (see those accounts). Allen and Loveridge (1933: 117) recorded three specimens from Mwanza on the southern margin of Lake Victoria in Tanzania under the name muansae thinking they represented topotypes of that form, but the holotype of muansae from Mwanza is very large with dark pelage (Matschie, 1911) and is an example of A. niloticus, while their sample is clearly the much smaller and paler A. somalicus; Mwanza is probably another site of sympatry.