Arvicanthis neumanni Matschie 1894

Arvicanthis neumanni Matschie 1894, Sitzb. Ges. Naturf. Fr. Berlin, 1894: 204.

Type Locality: C. Tanzania, Kondoa District, Barungi.

Vernacular Names: Neumann's Arvicanthis.

Synonyms: Arvicanthis reptans Dollman 1911; Arvicanthis somalicus Thomas 1903 .

Distribution: N and E Rift Valleys of Ethiopia (Yalden et al., 1976, 1996), 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, including base of Mt Kilimanjaro (Grimshaw et al., 1995).

Conservation: IUCN – Lower Risk (lc) as A. somalicus .

Discussion: 2n = 62, FN = 66 or 67 for Ethiopia (Baskevich and Lavrenchenko, 2000); 2n = 53-54, FN = 62 for Tanzania (Castiglia et al., 2003 a; Fadda and Corti, 2001), but more precisely 2n = 53-54 due to a Robertsonian fusion and derived from a larger sample (Fadda et al., 2001 b). Under the name somalicus Thomas (1903 a), A. neumanni has been treated as a species (G. M. Allen, 1939; Dollman, 1911; Ellerman, 1941; Hollister, 1919), and with an exception or two (e.g., Misonne, 1974), retains that status (Corti and Fadda, 1996; Ducroz et al., 1998; Fadda and Corti, 2001; Musser and Carleton, 1993; Rousseau, 1983; Yalden et al., 1976). Both reliable published records (see above) and specimens we examined document the northern and central range of A. neumanni . Known southern limits of the species are defined by samples from the Mawele region south of Tabora (Mwanasomano's, 31 mi [50 km] S Tabora) in C Tanzania and southeast of there at Kilosa in EC Tanzania (specimens in MCZ). The species is sympatric with both A. niloticus and A. nairobae (see those accounts). G. M. 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 the much smaller and paler A. neumanni; Mwanza is probably another site of sympatry.

Specimens from the southern margin of the range in Tanzania (Dodoma) were used in the geometric morphometric analysis by Fadda and Corti (2001) who noted they had small skulls as in A. neumanni from Kenya, Somalia, Ethiopia, but were shaped differently, indicating they represented either a separate species or a distinctive geographic variant within A. neumanni . The large series we examined from the region, including material from Dodoma, exhibit the small size and pelage characteristics common to samples from farther north in Kenya, Ethiopia, and Somalia; it would not be surprising to discover geographic variation within A. neumanni considering its extensive East African range. Alternately, if the Tanzanian population is a different species (the karyotype of A. neumanni from specimens collected elsewhere in Tanzania is different from Ethiopian samples; Fadda and Corti, 2001), A. neumanni would be the correct name for it, and A. somalicus would be the species with a range through Kenya to Somalia, S Ethiopia, and SE Sudan. After reporting karyotypes of their samples from NE Tanzania, Fadda et al. (2001 b) compared the material to large series from the central plateau of Tanzania and relevant holotypes, concluding "that further analysis is needed before deciding on the exact systematic position of the different Arvicanthis populations of this part of Tanzania."

Spermatozoal morphology of A. neumanni was described by Baskevich and Lavrenchenko (1995, as somalicus) who noted that it is the most distinctive compared to other species of Arvicanthis sampled ( A. abyssinicus, " dembeensis " and " A. sp."). Phylogenetic analysis of mtDNA cytochrome b sequences indicated A. neumanni (Tanzanian samples) is the basal member of a clade also containing A. abyssinicus and A. niloticus (Ducroz et al., 1998) . Cytogenetic data also places those three species, along with A. blicki, in the same phylogenetic lineage (Castiglia et al., 2003 a).