Family Bovidae
Tragelaphus angasii Nyala Fr. Nyala; Ger. Tiefland-Nyala Tragelaphus angasii Angas, 1849. Proc. Zool. Soc. Lond. 1848: 89 [1849]. South Africa, KwaZulu–Natal, ‘Hills that border upon the northern shores of St. Lucia Bay, in the Zulu country, lat. 28° south’. [Attribution to Angas, 1849, and not Gray, follows Grubb 2004, 2005].
Taxonomy There are no recognized subspecies. Genetic variation, on the basis of microsatellite, mitochondrial control region and allozyme markers, occurs between the Malawi, Mozambique and KwaZulu–Natal populations and it is postulated that this geographic variation is a function of a distribution pattern stemming from habitat specificity (Grobler et al. 2005). Synonyms: none. Chromosome number: 2n = 55 for ? and 2n = 56 for / (Wurster & Benirschke 1968, Wallace 1980). Description No other antelope shows such extreme sexual dimorphism as the Nyala, with adult ?? almost twice the size of // (Anderson 1976). Females, and young of both sexes, russet brown, with up to 18 vertical white stripes running from shoulders to hindquarters. At one year of age general coat colour of ?? is still same as //, but hair on neck has darkened while that on throat, sides of belly and dorsal ridge has grown noticeably longer than in //. Change in coat colour and length occurs rapidly between 14 and 16 months of age, the age at which spermatogenesis begins. This is accompanied by rapid increases in testis weight and seminiferous tubule diameter. Adult ?? are predominantly charcoal grey; lower legs remain russet brown, stripes and spots are retained and animals develop a white chevron on top of the muzzle. Up to three white spots on the cheeks and white spots on the upper hindleg. Bases of backs of ears white. Dorsal crest of long hair (dark on neck), and a heavy fringe of long hair (slightly darker than hair on body) on underparts of the neck to the belly. Long hair on tail dark, but underside white; this is very obvious in the male dominance ritual. In older individuals the stripes are reduced to three or four, or are absent entirely.Very rarely adult ?? occur that have retained their juvenile pelage (those that have been examined exhibited either cryptorchidism or had undeveloped testes). Adult // may or may not have a white chevron present between the eyes, also have a dorsal crest (though they lack the fringe of hairs on the throat and belly) and the lower parts of the legs do not contrast with the overall body colouration as is the case in ??. Both sexes have glands at the base of the false hooves, but inguinal and preorbital glands are absent. Females have two pairs of inguinal nipples. Aberrant-coloured Nyalas have been recorded. Dixon (1964) reported a ? from Mkuzi G. R., KwaZulu–Natal, which was pale beige in colour, and Lobão Tello & Van Gelder (1975) recorded a pale yellowish-coloured / and a palomino-coloured ? from Zinave N. P. in Mozambique. Only ?? have horns, which are keeled and grow in a shallow spiral. Horns first develop between five and six months (Anderson 1986). In adult ?? the tips of the horns are whitish partly as a result of the frequent ‘horning’ of moist earth when animals visit a waterhole. Age determination is discussed by Anderson (1986): adult dentition is attained at two years by which time the horns are half-grown (reaching mature size at 4.5 years). top: Adult male Nyala Tragelaphus angasii; middle: Adult female Nyala Tragelaphus angasii; bottom: Subadult Nyala Tragelaphus angasii.
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Geographic Variation None recorded, but see Taxonomy.