A new species of Graphiurus, G. walterverheyeni, is described. It is represented by two young adults, a female (holotype) and male (paratype), obtained from two sites in the central Congo Basin, Democratic Republic of the Congo. The new species is the possible morphological and phylogenetic counterpart of G. crassicaudatus, endemic to West Africa. Although the new species resembles G. crassicaudatus in texture and coloration of pelage, along with certain derived cranial features, G. walterverheyeni, n. sp., is separated not only by its much smaller body size as evidenced by the significant contrasts in external, cranial, and dental metrics between the two species, but also by proportional differences.The South Central faunal region of equatorial Africa (Grubb, 1978, 1982, 2001; Colyn, 1991; Colyn and Van Rompaey, 1994; Happold, 1996), and the Salonga-Lukenie-Sankuru landscape (Congo Basin Forest Partnership, 2006), identify the biogeographic landscape of G. walterverheyeni, n. sp. Scant habitat information associated with the specimens suggests that this Congo Basin endemic occurs in seasonally flooded tropical lowland forest formations. Two other species of Graphiurus, G. lorraineus and G. surdus, are broadly sympatric with the new species, but neither has been recorded from the two collection localities.Determining species diversity of sub-Saharan dormice embraces epidemiological concerns in addition to strictly taxonomic and biogeographic inquiries. The first documented outbreak of human monkeypox outside Africa occurred in the midwestern United States in 2003 and was associated with a shipment of captive mammals (Funisciurus sp., Heliosciurus sp., Cricetomys sp., Atherurus sp., Hybomys sp., and Graphiurus sp.) from Ghana (Guarner et. al., 2004). Following this outbreak, certain species of African dormice occurring in West and Central Africa are currently being scrutinized as possible hosts of monkeypox virus (Orthopoxviridae), which can produce a severe illness in humans resembling smallpox (Hutson et al., 2007; Levine et al., 2007). Understanding the ecology and epidemiology of this virus requires correct identification of mammalian host species so that accurate, relevant geographic and ecological data can be analyzed.