Following the award of a Winston Churchill Memorial Trust (WCMT) Fellowship the author was able to visit the Charles P. Alexander (1889–1981) collection at the Smithsonian Institution, Washington D. C. to study craneflies gifted to him from fieldwork in Cameroon. They were collected by Malaise trap in forest clearings near streams on Mount Kupe, near Nyasoso, Cameroon. 21 new species of cranefly (Diptera: Tipulidae and Limoniidae): Dolichopeza (Dolichopeza) vicki sp. n., Nephrotoma mawdsleyi sp. n., Baeoura nyasosoensis sp. n.,Ellipteroides (Ellipteroides) nigromaculatus sp. n., Hovamyia gelhausi sp. n.,Limnophilomyia (Limnophilomyia) alexanderi sp. n., Ormosia (Neserioptera) cameroonensis sp. n., Afrolimnophila mederosi sp. n., A. oosterbroeki sp. n., Neolimnomyia kupensis sp. n., Pseudolimnophila (Pseudolimnophila) staryi sp. n., Achyrolimonia prycei sp. n., Dicranomyia (Dicranomyia) tuberculata sp. n., D. (Idioglochina) stubbsi sp. n., Elephantomyia (Elephantomyia) gilsonae sp. n., Libnotes (Afrolimonia) trimaculata sp. n., Metalimnobia (Tricholimnobia) krameri sp. n., Thaumastoptera (Thaumastoptera) churchilli sp. n., Toxorhina (Ceratocheilus) holvia sp. n., Trentepohlia (Trentepohlia) zorro sp. n., and Trichoneura (Xipholimnobia) jacksoni, and a new species of fold-wing cranefly (Diptera: Ptychopteridae): Ptychoptera (Ptychoptera) fasbenderi sp. n., are described. 18 species of cranefly known from elsewhere in the Afrotropical region are recorded here from Cameroon for the first time: Gonomyia (Leiponeura) hyperion Alexander, 1956, Limnophilomyia (Limnophilomyia) medleriana Alexander, 1976, Styringomyia vittata Edwards, 1914, Afrolimnophila hartwigi (Alexander, 1974), A. urundiana (Alexander, 1955), Austrolimnophila (Phragmocrypta) fulani Alexander, 1974, Hexatoma (Eriocera) brevifurca Alexander, 1956, H. (E.) trichoneura Alexander, 1956, H. (E.) tumidiscapa (Alexander, 1920), Medleromyia nigeriana Alexander, 1974, Achyrolimonia recurvans (Alexander, 1919), Atypopthalmus (Atypopthalmus) submendicus tuberculifer (Alexander, 1956), Dicranomyia (Dicranomyia) redundans (Alexander, 1956), Libnotes (Afrolimonia) rhanteria (Alexander, 1920), L. (A.) illiterata (Alexander, 1937), Limonia woosnami (Alexander, 1920), Orimarga (Protorimarga) bequaertiana (Alexander, 1930) and Toxorhina (Ceratocheilus) nigripleura (Alexander, 1920). In total 40 species are presented as new for Cameroon. A further 23 species already known from Cameroon were identified, and are listed here as some of them have not been recorded since their original description close to, or in some cases over, a hundred years ago.