Tragelaphus larkenii (St. Leger, 1931)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 606

28.

Nile Sitatunga

Tragelaphus larkenii

French: Sitatunga du Nil / German: Nil-Sitatunga / Spanish: Sitatunga del Nilo

Other common names: Nile Marsh Buck

Taxonomy. Limnotragus spekei larkenii St. Leger, 1931 ,

Bahr-el-Ghazal, 50 miles S of Yambio, SW Sudan.

The Nile Sitatunga has been variously included with T. spekii or T. gratus , butit is diagnostically different from other sitatunga. The new separation of T. spekii into five species, each with its own nomenclatural history, makes demarcation of current ranges difficult. Further research is required to ascertain if the south-western Sudan and Sudd Swamp populations are both T. larkenii, or if it is confined to the type locality. Monotypic.

Distribution. Discontinuous and limited to wetland environments in two areas of S Sudan: small swamps in SW Sudan near the DR Congo border, where the type specimen was collected, and the Sudd Swamps (Bahr-el-Ghazal) of the upper White Nile. Maps and distributional information here are provisional pending future research.

Descriptive notes. No specific measurements are available, but the Nile Sitatunga is somewhat smaller than the Lake Victoria Sitatunga. Sitatungas are among the most sexually dimorphic tragelaphines relative to body weight, with mass of males as much as 170% of that of females. Unique to the sitatunga group, the hooves of all but the Nkosi Island Sitatunga (7. sylvestris ) are very elongated, with flexible toe joints and large false hooves that help prevent them from sinking into the mud and vegetation mats of their preferred swampy habitats but make them clumsy on dry land. The pelage of the Nile Sitatunga tends to be shorter, sparser, and less shaggy than that of other sitatunga species. Male Nile Sitatungas are rich dark brown, with 4-8 stripes, sometimes faint, and a lateral stripe of 12-15 spots, which may be reduced to 3-4 spots. Females are dark red-brown, with 6-7 faint or broken stripes and the lateralstripe of spots. The dorsal crest, running from the withers to rump, is usually white in both sexes, with considerable gray in the neck of the female. The inside of the front legsis white. Young are red-brown, with 6-9 stripes and a lateral stripe of spots; their dorsal crest may be white or all dark, and their neck is pale. Nile Sitatungas are relatively large in size and have a long face and narrow skull. Male-only keeled horns are spiraled 1-5 times and relatively short. Dental formulais10/3,C0/1,P 3/3, M 3/3 (x2) = 32.

Habitat. Sitatungas as a group, except the Nkosi Island Sitatunga, are described as semi-aquatic, limiting most of their activities to swamps, bogs, and marshes associated with rivers, streams, lakes, and lowland forests of poor drainage that are scattered intermittently throughout their range. They are excellent swimmers, will avoid danger by escaping to deep water, and are capable of submerging their entire body with little more than their nostrils above the surface. The original specimens of the Nile Sitatunga were collected in forested areas with thick undergrowth but lacking true swamps; instead, they had many small streams in deep ravines.

Food and Feeding. There is no specific information available for this species, but probably comparable to othersitatungas.

Breeding. There is no specific information available for this species, but probably comparable to other sitatungas.

Activity patterns. There is no specific information available for this species, but probably comparable to other sitatungas.

Movements, Home range and Social organization. There is no specific information available for this species, but probably comparable to othersitatungas.

Status and Conservation. Classified as Least Concern on The IUCN Red List (under 7. spekii ), which does not differentiate the five species identified here. Generally, numbers of sitatungas are stable in areas of low human population density and decreasing elsewhere. As many as 170,000 sitatungas may occur discontinuously throughout the group’s range in Africa, with about 40% living in protected areas. That number, however, is considered an overestimate, and local populations are threatened by loss of habitat, altered hydrology oftheir critical wetland habitats, livestock grazing and likely associated disease transmission, uncontrolled burning of swampland, and overharvest for subsistence and the bushmeat trade. Numbers of the Nile Sitatunga in the Sudd Swamps of southern Sudan were estimated at 1100 individuals in the early 1980s, and no estimates of numbers are available from south-western Sudan. Minimizing loss of wetland habitats and, critically, their interconnectedness, which minimizes isolation and permits dispersal and gene flow, is fundamental to the long-term conservation of all sitatungas, including the Nile Sitatunga.

Bibliography. Ansell (1972), Bro-Jorgensen (2008), East (1999), Groves & Grubb (2011), Huffman (2004q), IUCN/SSC Antelope Specialist Group (2008bi), Kingdon (1982, 1997), Nowak (1999), St. Leger (1931).

Figures

18. Western Bushbuck (Tragelaphus scriptus), 19. Central Bushbuck (Tragelaphus phaleratus), 20. Nile Bushbuck (Tragelaphus bor), 21. Lake Tana Bushbuck (Tragelaphus decula), 22. Ethiopian Highlands Bushbuck (Tragelaphus meneliki), 23. Eastern Coastal Bushbuck (Tragelaphus fasciatus), 24. Chobe Bushbuck (Tragelaphus ornatus), 25. Cape Bushbuck (Tragelaphus sylvaticus)

Distribution. Discontinuous and limited to wetland environments in two areas of S Sudan : small swamps in SW Sudan near the DR Congo border, where the type specimen was collected, and the Sudd Swamps (Bahr-el-Ghazal) of the upper White Nile. Maps and distributional information here are provisional pending future research.