Taxonomy

The current state of the taxonomy of the entire order Artiodactyla (even-toed ungulates) is in some disarray. New suborders and superfamilies have been created, and there seems to be some uncertainty whether Tsessebe still belong in the genus Damaliscus. For the purposes of this study, the classification of the three species used by the Antelope Specialist Group of the IUCN Species Survival Commission (ASG 1998) has been adopted:

• Roan antelope - Hippotragus equinus (Desmarest 1804)
• Sable antelope - Hippotragus niger (Harris 1838), subspecies H.n. niger
• Tsessebe - Damaliscus lunatus (Burchell 1824), subspecies D.l. lunatus

The taxonomic relationship of the three species within the antelope family Bovidae as given by Smithers (1983) is shown in Figure 1 .

Smithers (1983) notes that Ansell (1972) lists six subspecies of roan for the African continent, including a subspecies H. e. cottoni occurring in northern Botswana, the Caprivi and extending into Angola and southern Zaire. However, in the latest classification of the Antelope Specialist Group there is no mention of this subspecies and it seems there is no longer a valid basis for recognising any subspecies of roan antelope.

Apart from the Giant sable in Angola (H. niger variani), it seems that the taxonomic status of the other subspecies of sable (H. n. roosevelti which occurs in coastal Kenya and northern Tanzania, and H. n. kirkii found in the Selous Game Reserve) are under question at the moment.

Ansell (1972) lists 7 subspecies of Damaliscus lunatus but the Antelope Specialist Group has reduced this number to 5 subspecies: D. l. lunatus - Tsessebe in southern Africa; D. l. korrigum - Korrigum, in northern Benin, Nigeria and Cameroun; D. l. tiang - Tiang, occurring eastwards from Chad across southern Sudan to Ethiopia and northern Kenya; D. l. topi - Coastal Topi from East Africa and D. l. jimela - the Topi in western Tanzania extending into south-western Kenya and Uganda.

Physical Description

Roan are a large antelope, second only in size to eland. Adult males have a shoulder height of about 1.4 metres and weigh slightly under 300kg. Females are slightly smaller and lighter. Both sexes carry horns which rise from the head in a uniform backward curve and are ridged. The longest pair of horns on record (99 cm) are from a trophy taken in the Tokwe Valley, Zimbabwe (Best and Best, 1977). The females' horns are smaller than the males.

The body coat is greyish brown with touches of rufous colouring which varies amongst individuals. The legs are darker brown than the remainder of the body and the animal possesses a noticeable mane. The most distinctive features are the facial markings which resemble a black balaclava mask with elongated white 'cut-outs' around the eyes. The ears are unusually long with dark brown tufts on the tips.

Sable are slightly smaller than roan, with adult males standing under 1.4 metres at the shoulder and weighing about 230kg. There is a distinct dimorphism: older males have shiny black coats whilst females are dark brown. Subadults and juveniles of both sexes tend to be a lighter shade of brown. All have white bellies with the colour extending inside the rear legs and up to the base of the tail. The face is marked longitudinally with white stripes extending from each eye towards the muzzle.

Both sexes carry horns but the fully developed male horns are far larger than those of the females. The horns sweep back from the head in a characteristic curve, with the largest trophies from the southern African region being just over 50 inches.

Tsessebe are smaller than sable, with adult males standing about 1.2 metres at the shoulder and weighing about 140kg. The average female body weight is slightly less than 130kg. The general colour of the body is dark reddish-brown with a purplish sheen. The upper part of the head and muzzle is almost black. The colouration of the flanks and withers are darker than the remainder of the body giving the appearance of a 'watermark' from mid-body downwards. There is some yellowish colouring on the base of the tail, the back of the ears, the insides of the hind legs and on the abdomen. Tsessebe have a characteristic body shape which slopes downwards towards to the rump.

Both sexes possess horns which rise close together in the centre of the head and bend outwards and upwards in a uniform curve. A record trophy of 47cm (Best and Best, 1977) was taken in northern Botswana.