The Ruwenzori duiker is restricted only to west Uganda and probably adjacent zones of east former Zaire in the Ruwenzori Mts. range (East, 1996; Wilson & Reeder, 1993). Its distribution map was first obtained from Kingdon (1971-77), then updated with information from East (1988) and by adjusting locality records on the basis of the elevation data set. Dr. R. East revised a preliminary output ( 23 June '97 )
The initial taxonomic record is taken from Wilson and Reeder (1993). The Ruwenzori red duiker is included in the subgenus Cephalophorus [Gray, 1842] (Nowak, 1991). C. rubidus has been treated as a race of Cephalophus natalensis and/or C. nigrifrons, although Kingdon (1982, 1997) elevated it a species in its own right on the basis of coat characteristics (Wilson, 1987). This species may be actively hybridizing with the low-elevation C. nigrifrons in the Ruwenzori mountains where the ranges of the two species overlap at about 3,000 meters (Kingdon, 1982; Kingdon, 1997). Wilson (1987) strongly recommended field studies be carried out to determine the taxonomic status of this species.
Categorical-discrete (CD) distribution model
The species occurs in Afro-alpine and sub-alpine zones (Kingdon, 1997; East, 1988). Endemic to the Ruwenzori mountains along the Uganda/Congo-Kinshasa border (East, 1999). The presence of C. rubidus in the Congo has yet to be confirmed (East, 1999).
The pelage on the body is a glossy rufous to rich chestnut-red (Thomas, 1901; Kingdon, 1982). The undersides are much paler than the back (with the differentiation being poorly defined), and the axillary and groin regions are white (Thomas, 1901). A dark greyish-brown dorsal strip is present from the neck to the base of the tail (Thomas, 1901; Kingdon, 1982). This coloration is created through a zone of hairs that are dark grey at the base, but red at the tip, while the underfur of the rest of the body is a creamy-white (Kingdon, 1982). This pattern of coloration is also seen in the red-flanked duiker (Cephalophus rufilatus), which Kingdon (1982) used as evidence that C. rubidus is not a subspecies of Cephalophus nigrifrons. The sides of the neck are particularly bright rufous, while the nape is browner than the greyish dorsal stripe along hte back (Thomas, 1901). The hairs of the neck are directed backwards (Thomas, 1901). The hind legs are almost black in color (Kingdon, 1982). The forelegs are the same reddish color as the body, but possess dark brown markings at the joints, giving them a darker appearance as well (Kingdon, 1982). The tail is primarily black grizzled with red and white hairs on the dorsal surface, while the underside and tip are white (Thomas, 1901).
The head coloration is not significantly different from the rufous of the body, although there is a black or dark brown blaze on forehead, which stretches from the the muzzle to the crown (Kingdon, 1997). Skull length is 15.3-16.5 cm, slightly smaller than that of the black-fronted duiker (C. nigrifrons kivuensis) which inhabits the lower altitudes of the Ruwenzori mountains (Kingdon, 1982). The horns, presumably present in both sexes, measure 8-9 cm in length (Kingdon, 1982). This duiker is very poorly studied, in part due to the uncertainty regarding its taxonomic status. All information presented here is from Kingdon (1982 and 1997). C. rubidus inhabits Afro-alpine and subalpine zones in the Ruwenzori mountains at elevations above 3,000 meters. This habitat is characterized by Hagenia woodland and bamboo zones at lower elevations.
The Ruwenzori red duiker is reported as primarily diurnal, but, depending on weather conditions (especially rain), the activity period may be shifted out of necessity to the night. As a result, activity patterns of this duiker likely vary seasonally. C. rubidus lives at high elevations, often feeding close to snowline, and is occasionally spotted by climbers trekking up to the Ruwenzori peaks (although as this species declines, sightings are becoming increasingly rare). This duiker often feeds in the open on exposed and rocky scree slopes, as well as in boggy, densely overgrown or wooded areas. Available browse in this highly diverse pasture includes herbs such as wild parsley, balsams, violets, sorrels, and Galium, a low-growing "scrambling" herb which is preferentially eaten by a wide diversity of high altitude herbivores. Information on the types of plants selected is not available.