Four diatom taxa from East Africa, Surirella ovalis var. apiculata, S. ovalis var. apiculata f. minor, S. fasciculata and S. olungensis are discussed. The species were observed in material sampled by Fülleborn at the beginning of the 20th century and formerly studied and named – except the last – by O. Müller. The first two taxa were described from a sample of a hot spring near Utengule (Tanzania) and from Lake Rukwa respectively. Surirella fasciculata, related to the previous ones, was described from Lake Ngozi (Tanzania). Besides translations of the original descriptions, lectotypes and/or epitypes were designated and their distribution given based on literature. A new taxon, also related to Surirella ovalis, was observed in a sample from the Olunga river (Tanzania) and is here described as a new species: Surirella olungensis. Besides this new taxon, some aberrant forms were observed in the same historical sample.