Present in the Congo basin from the marine lower Congo up to the upper Lualaba, including the lower Congo, Pool Malebo, middle Congo River, Mai Ndombe, Sankuru, Ruki, Ubangi (Ref. 43912), Itimbiri, Lindi-Tshopo (Ref. 43912, 106290), Aruwimi (Ref. 106290), Lomami (Ref. 106245), Wagenia Falls and Lualaba (Ref. 43912, 106245); not reported upstream of Lake Mweru. Type locality of the syntypes of Parailia congica: "Ebinga (river of Lake Leopold II)" and "Boma" (Ref. 43912). Type locality of the syntypes of Parailia longifilis: "Banzyville, Ubangui" (Ref. 43912). Also Ref. 3570, 78218.