2n = 28, FN = 30 (Matthey, 1959). At one time listed as a subspecies of P. tullbergi (e.g., Hollister, 1919), jacksoni is a distinct species occurring sympatrically with P. tullbergi (G. M. Allen, 1939; Ansell, 1978; Van der Straeten and Dieterlen, 1987; Van der Straeten and Dudu, 1990; Lecompte et al., 2001). The problem of identifying the holotype of P. jacksoni, as well as current names associated with the species, was reviewed and discussed by Van der Straeten and Dieterlen (1987), Van der Straeten and Dudu (1990), and Van der Straeten and Kerbis Peterhans (1999). Van der Straeten and Dudu (1990) regarded montis and peromyscus as valid species and Van der Straeten and Kerbis Peterhans (1999) claimed that montis, peromyscus, sudanensis, and viator, all names that we place in synonymy, are separate species. The canonical analyses presented by those authors, however, employing series representing these taxa and other distinct species of Praomys (P. degraaffi and P. mutoni), do not indicate any significant separation between clusters identified as montis, peromyscus, sudanensis, and viator and topotypes of jacksoni. Praomys jacksoni as we list it here may be composite, but until the forms representing potential species (viator, montis, peromyscus, sudanensis) have been clearly diagnosed and their geographic ranges described we include them here under P. jacksoni.

Several pertinent reports cover: craniometrical comparisons among four samples of P. jacksoni collected at different altitudes (850-3300 m) in the Kivu region of E Dem. Rep. Congo (Van der Straeten and Dieterlen, 1992); altitudinal distribution of P. j. montis on Ugandan slopes of Ruwenzori Mtns (Kerbis Peterhans, 1998, who regarded montis as a Ruwenzori endemic); specimens from Kalinzu forest of SW Uganda that were collected on the forest floor and on woody vines 1.5 m above the ground (Lunde and Sarmiento, 2002); samples from mountain chain in W Cameroon and SE Nigeria reported as "Praomys cf. jacksoni" (Hutterer et al., 1992a); habitat and distribution on Ugandan slopes of Mt Elgon (Clausnitzer and Kityo, 2001); and samples from Kibale Forest in Uganda (Hoffmann, 1997). Ziegler et al. (2002) listed P. jacksoni from C Guinea but the voucher material comes from so far west of the nearest documented occurrence (Nigeria) that we are dubious of its identification.