Species
Arvicanthis niloticus
Description
Arvicanthis niloticus (É. Geoffroy Saint-Hilaire, 1803)
This species has been reported as A. dembeensis in previous studies (Yalden et al. 1976, 1996). It corresponds to A. niloticus clade C1 in Dobigny et al. (2013), but it seems to be a valid species, genetically very distinct from (and not sister to) A. niloticus “C2- C4” (sensu Dobigny et al. 2013) at both mitochondrial and nuclear markers (Bryja et al. 2019). The samples from Egypt (i.e. type locality of A. niloticus) belong to the mitochondrial clade C1 and the name “niloticus” should be therefore used for the species distributed along the Nile River, in northern Ethiopia and Yemen. On the other hand, the widely distributed species in the belt of Sudanian savanna from Senegal to southern Ethiopia and western Kenya (genetically structured from west to east) should receive another name; here we follow Bryja et al. (2019) by using provisionally the name A. niloticus “C2-C4” (see below). Recent genetic results therefore support previous views, e.g. based on skull morphology (Fadda & Corti 2001), that populations living along the Nile valley, in northern Ethiopia and Yemen represent the same species (see also taxonomic discussion in Musser & Carleton 2005), distinct from the Sudano-Sahelian taxon, i.e. A. niloticus “C2-C4”. There are two mitochondrial lineages of A. niloticus in Ethiopia. The first one was found around Lake Tana and Alatish NP and it also occurs along the Nile Valley in Sudan (Abdel Rahman et al. 2008), while the second is distributed in the Tigray Region and along the eastern escarpment of the Abyssinian massif (Bryja et al. 2019).
Arvicanthis niloticus “C2-C4” (sensu Bryja et al. 2019)
This is a typical species of the Sudanian savanna/Sahel ecosystem (Bryja et al. 2019). Its phylogeographic structure was studied by Dobigny et al. (2013), who defined four main clades within A. niloticus sensu lato (C1-C4). The easternmost clade C1 is considered here as A. niloticus s. str. (see above), while the remaining clades represent species that should receive another scientific name. Numerous descriptions originate from Kenya and Uganda (see Allen 1939), from where substantial morphological variability has been reported (Fadda & Corti 2001) and where this taxon clearly occurs. It will be necessary to perform combined genetic and morphological analysis from this region to answer the question of how many species exist there and how they are related to A. niloticus “C2-C4” in central and western Africa. Similarly, there are at least four descriptions from “Anglo- Egyptian Sudan” (Allen 1939), i.e. current Sudan and South Sudan, which is a potential contact zone of A. niloticus s. str. and A. niloticus “C2-C4”. Detailed analysis of the type material and genomic analysis of potential contact zone, especially in Sudan, is required to correctly delimit these taxa (Bryja et al. 2019). The clade C2 of A. niloticus “C2-C4” is distributed in Sudanian savanna from northern Cameroon to southern Ethiopia and western Kenya. Very likely, it is also the species present in the Gambella region, west of the River Omo, from where DNA data are missing (Orlov et al. 1992, Bulatova et al. 2002). The localities of A. dembeensis (= A. niloticus s. str.) from the southern part of the Rift Valley reported by Yalden et al. (1976) very likely represent A. niloticus “C2- C4”.
Taxonomy
Arvicanthis niloticus is a species. It belongs to the Muridae family.
