Two rnicrosporidian genera, Anncaliia Issi, Krylova, & Nicolaeva 1993 and Brachiola Cali et al. 1998, possess a Nosema-type life cycle and unique cell surface ornarnentations, which include precocious electron-dense coating of the plasmalernma and a variety of secretory structures deposited on the parasite surface and scattered in the host cell cytoplasm. Comparative analysis Of Ultrastructure of Anncaliia meligethi (the type species of the genus Anncaliia) and of B. vesicularum and B. algerae (the best-studied merribers of the genus Brachiola) clearly demonstrated that these microsporidia share many distinctive morphological features. The comparison of small subunit ribosomal DNA sequences showed high sequence identify of A. meligethi and B. algerae. Phylogenetic analyses indicated that the rDNA sequences of A. meligethi clustered with those of B. algerae Suggesting a close relatedness of these microsporidia. The combination of molecular and morphological data provided clear evidence that these microsporidia belong to the same genus and therefore, warranted emendation of the venus Anncaliia and establishments of the following new combinations: Anncaliia vesicularum nov. comb., Anncaliia algerae nov. comb., Anncaliia connori nov. comb., and Anncaliia gambiae nov. comb.. The generic name Brachiola is submerged according to the rule of priority.