Similarly, based on eleven skins from this taxon and other sassaby skins from further south, and field observations, the pelage was observed to average darker from south to north, with that of the Bangweulu animals being described as chocolate-brown. There is also probably a cline in the average body size of the animals, with those of Bangweulu being the largest. Other less definite characteristics are a higher braincase on average, a wider zygoma on average, and a longer rostrum due to on average longer maxillary teeth rows. The horns had a slightly wider spread and were longer on average. In adults of both sexes, the horns grow symmetrically to form a sphere, as opposed to the more semi-lunate profile of lunatus. The larger size, spherical horn profile and darker pelage could be used in the field according to Cotterill. Another possible difference is in the protozoa found in the digestive tract, based on two studies, both taxa contain the same eleven species in their gut flora as found in all topi, but Epidinium lunatus had up till then only been identified in a study of sassaby in South Africa and Ostracodinium damaliscus had recently been described from the rumen of sassaby from Zambia, thus there is potentially a possibility that these protozoa might be restricted to these particular populations and thus be diagnostic.
