Nosema maroccanus Krilova et Nurzhanov, 1987 was isolated from the Moroccan locust Dociostaurus maroccanus Thunb. in Uzbekistan. Its description, based on one of the first ultrastructural studies of microsporidia from orthopteran hosts, lacked information on the details of cell surface structure, which are considered to be very important in modern taxonomy. We have re-investigated the material upon which the original description of N. maroccanus was based and revealed new ultrastructural characters of its cell surface. Late meronts are surrounded with microtubuli, about 20 nm in diameter, attached to the membrane, later replaced with electron dense granules, forming a typical coating of the sporont's surface (the primordium of exospore). Mature spores are also surrounded with a layer of microtubuli. Host cell cytoplasm contains small vesicles with electron-dense cores, up to 50 nm in diameter, surrounding late meronts, sporogonial stages and spores of the parasite. Polar tube is slightly anisofilar. These characters disagree with the diagnosis of Nosema, but fit that of the recently established genus Tubulinosema. Hence, we transferred the species studied into this genus, establishing Tubulinosema maroccanus comb. nov. Analysis of cell surface ultrastructure of two Tubulinosema species from Orthoptera showed that they shared two characters not mentioned in the diagnosis of the genus. Therefore, the diagnosis of Tubulinosema was modified to include two more characters: presence of vesicles with electron-dense cores surrounding sporogonial stages and presence of microtubuli not only in late meronts, but also, in some species, in spores.