The Sitatunga or Marshbuck (Tragelaphus spekii) is a swamp-dwelling antelope found throughout central Africa, centering on the Democratic Republic of the Congo, the Republic of the Congo, Cameroon, parts of Southern Sudan, Equatorial Guinea, Burundi, Ghana, Botswana, Rwanda, Zambia, Gabon, the Central African Republic, Tanzania, Uganda and Kenya. The sitatunga is confined to swampy and marshy habitats. Here they occur in tall and dense vegetation as well as seasonal swamps, marshy clearings in forests, riparian thickets and mangrove swamps.
The scientific name of the sitatunga is Tragelaphus spekii. The species was first described by the English explorer John Hanning Speke in 1863. Speke first observed the sitatunga at a lake named "Little Windermere" (now Lake Lwelo, located in Kagera, Tanzania). In his book Journal of the Discovery of the Source of the Nile, Speke called the animal "nzoé" (Kiswahili name for the animal) or "water-boc" (due to its resemblance to the waterbuck). The scientific name has often been misstated as T. spekei, and either Speke or Sclater is referred to as the binomial authority.
Speke had stated in a footnote in his book that the species had been named Tragelaphus spekii by English zoologist Philip Sclater. However, according to the International Code of Zoological Nomenclature (Article 50.1.1) and the International Commission on Zoological Nomenclature, that acknowledge the person who first described the species, simply declaring Sclater as the authority in a footnote is insufficient to recognise him as the author. Hence, Speke was recognised as the correct authority and T. spekii (where spekii is the genitive of the Latinised "Spekius") was considered the correct name for the species.
The sitatunga is placed under the genus Tragelaphus and in the family Bovidae. In 2005, Sandi Willows-Munro of the University of KwaZulu-Natal (Durban) carried out a mitochondrial analysis of the nine Tragelaphus species. mtDNA and nDNA data were compared. The results showed that sitatunga plus bongo (T. eurycerus) form a monophyletic clade with the mountain nyala (T. buxtoni) and bushbuck (T. scriptus). The greater kudu (T. strepsiceros) split from this clade approximately 8.6 million years ago.
Within Tragelaphus, the bushbuck, bongo, sitatunga and nyala (T. angasii) are particularly close relatives. The bushbuck and sitatunga are genetically similar enough to hybridise. Hybrids between bongo and sitatunga have proved to be fertile. The sitatunga is more variable in its general characters than any other member of the tribe Strepsicerotini, that consists of the genera Taurotragus (elands) and Tragelaphus, probably because of their confinement to swampy and marshy habitats.
On the basis of physical characteristics such as hair texture, coat colour and the coat stripes, up to ten subspecies of the sitatunga have been described. However, these factors may not be reliable since hair texture could vary with the climate, while pelage colour and markings vary greatly among individuals. Moreover, the coat might darken and the stripes and spots on it might fade with age, especially in males. The species might even be monotypic, however, based on different drainage systems, three distinct subspecies are currently recognised:
T. s. spekii (Speke, 1863): Nile sitatunga or East African sitatunga. Found in the Nile watershed.
T. s. gratus (Sclater, 1880): Congo sitatunga or forest sitatunga. Found in western and central Africa. (See below)
T. s. selousi (W. Rothschild, 1898): Southern sitatunga or Zambezi sitatunga. Found in southern Africa.
The Sitatunga or Marshbuck (Tragelaphus spekii gratus) seen in Dzangha Ndoki Central Africa
