The sitatunga or marshbuck (Tragelaphus spekii) is a swamp-dwelling antelope found throughout Central Africa, centering on the Democratic Republic of the Congo, Cameroon and parts of Southern Sudan as well as in Ghana, Botswana, Zambia, Gabon, Tanzania, Uganda and Kenya.
The scientific name of the sitatunga is Tragelaphus spekii. Formerly included in the genus Limnotragus,  the animal is presently placed under the genus Tragelaphus and in the family Bovidae. Within Tragelaphus, the bushbuck, sitatunga and nyala are particularly close relatives. The sitatunga is almost indistinguishable from the nyala, except by pelage and spoor. The sitatunga and bushbuck are genetically similar enough to hybridise. Hybrids between the bongo and sitatunga have proved to be fertile.
The species was first described by English explorer John Hanning Speke in 1863. Speke first observed the sitatunga at a lake named "Little Windermere" (presently known as Lake Lwelo, located in Kagera, Tanzania). In his book Journal of the Discovery of the Source of the Nile, Speke called the animal "nzoé" or "water-boc" (due to its resemblance to the waterbuck), and added in a footnote that the species had been named Tragelaphus spekii by Philip Sclater. However, according to Article 50.1.1 of the International Code of Zoological Nomenclature and International Commission on Zoological Nomenclature, this is insufficient to state Sclater as the author. Speke pointed out in his book that though "closely allied" to the waterbuck, the sitatunga lacks stripes and is spotted instead. The toes are long, and the coat well-adapted to its moist habitat.
The sitatunga is more variable in its general characters than any other member of the tribe Strepsicerotini, probably because of their confinement to swampy and marshy habitats. On the basis of physical characteristics such as hair texture, coat colour and the presence or absence of stripes, three subspecies of the sitatunga have been recognised:
- T. s. spekii Speke, 1863; also called East African sitatunga.
- T. s. gratus P. L. Sclater, 1880; also called forest sitatunga.
- T. s. selousi W. Rothschild, 1898; also called Zambezi sitatunga.
The sitatunga is a medium-sized antelope. It is sexually dimorphic, with males considerably larger than females. The head-and-body length is typically between 115–170 cm (45–67 in). Males reach approximately 88–125 cm (35–49 in) at the shoulder, while females reach 75–90 cm (30–35 in). Males typically weigh 70–125 kg (154–276 lb) and females 50–57 kg (110–126 lb). The tail is 30–35 cm (12–14 in) long.
As an adaptation to its swampy and marshy habitat, the sitatunga has a shaggy, water-resistant coat. The coat colour varies geographically, but, in general, is a rufous red in juveniles and chestnut in females. The coats of males darken with age, becoming gray to dark brown. Males develop a rough and scraggy mane, usually brown in colour, and a white dorsal stripe. There is a chevron between the eyes of the males. There are white facial markings, as well as several stripes and spots, though they are only faintly visible. White patches can be observed on the throat, near the head and the chest.
As a prominent sign of sexual dimorphism, only the males possess horns. The spiral horns shown one or two twists, and are 45–90 cm (18–35 in) long. Both horns are tipped with ivory. The pasterns are flexible. The hooves of the male are elongated and widely splayed, serving as another adaptation to the marshy environment. They can reach a length of up to 16 cm (6.3 in) in the hindlegs and 18 cm (7.1 in) in the forelegs. A pair of inguinal scent glands are present.
- IUCN SSC Antelope Specialist Group (2008). Tragelaphus spekii. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 March 2009. Database entry includes a brief justification of why this species is of least concern.
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