Lake Rukwa, and to the east by Lake Tanganyika. Most of the basin is miombo woodland, with Brachystegia spiciformis and Julbernardia globiflora as the dominant trees. There are extensive areas of flooded grassland in the central Malagarasi-Moyowosi basin, and along the middle Ugalla River to the southwest. History According to ecologist Rosemary Lowe-McConnell, "the Malagarasi and the Rungwa River are assumed to be relict headwaters of the extended pre-rift Zaire system". The Malagarasi pre-dates Lake Tanganyika and was in pre-rift times a tributary of the Congo River to its west. Lake Tanganyika has since said to have "undergone both transgression and regression, depositing new sediments, altering the delta, and changing the course of the river". Over its history, the lake level has altered dramatically between ; historical accounts from the late nineteenth century indicate that it was about higher than it is today. Culture Local tribes have nicknamed the Malagarasi as "the river of bad spirits". In the late 19th century, the Wavinza people, who ran the river's ferry service from the left bank, avoided assimilation with the Wanyamwezi people because of the natural barrier formed by the Malagarasi. Also on the other bank were the Wangoni (Watutu Zulus). Henry Morton Stanley, who considered missionaries important to Africa's "civilizing process", stated that missionaries could follow the Malagarasi and participate in "conversion-tours to Uvinza, Uha, and Ugala". Flora and fauna The tree species in the Malagarasi basin include Albizia gummifera, Bridelia micrantha, Cyperus papyrus, Diospyros mespiliformis, Ficus sycomorus, Ficus verruculosa, Isoberlinia spp., Khaya senegalensis, Parkia filicoidea, Phoenix reclinata, Syzygium cordatum, and Syzygium owariense. The prominent grasses in the valley grasslands are species of Hyparrhenia, Themeda, and Echinochloa. The Malagarasi sardine (Mesobola spinifer) is endemic to the river. The Malagarasi contains several fish species which occur in the Congo River Basin but not in Lake Tanganyika. Giant freshwater Mbu pufferfish, however, occur in both the Central and Upper Zaire Basin and the Malagarasi River. Malagarasi-Muyovozi Wetlands The Malagarasi-Muyovozi Wetlands lie in the middle of the basin, at 1200 meters elevation at the confluence of the Malagarasi with the Gombe, Muyovozi, Ugalla, and other tributary rivers. The wetland includes of dry-season lakes and open water including Sagara and Nyamagoma lakes, and of permanent papyrus swamp. Seasonally-flooded grasslands on the surrounding floodplain vary seasonally and with annual rainfall, and can cover up to . The papyrus swamps are dominated by the sedge Cyperus papyrus