Figure 7. – Evolution of the estimated number of species based on various definitions of the Congo basin: Central Congo, i.e. Kinshasa to Kisangani, without Kasai upstream from Mushie (Poll and Gosse, 1963); without lakes Bangweulu and Mweru (Roberts, 1972); entire Congo (Poll, 1973); excluding Lake Tanganyika (Lowe-McConnell, 1987); excluding lakes Tanganyika and Mweru, primary freshwater species (Teugels and Guégan, 1994); Zaïre, probably only includes primary freshwater species (Lévêque, 1997); Zaïre, probably includes primary, secondary and peripheral species (Lévêque, 1997); Congo River system, at least 700 species (Skelton, 2001); Congo and Lake Tanganyika (Revenga and Kura, 2003); Congo River system (Thieme et al., 2005); the Congo (Dumont, 2009); Congo basin including the Rift Valley region with lakes Tanganyika and Kivu and the Malagarasi basin (Snoeks et al., 2011).