Haemoproteid parasites of Passer spp

The taxonomic status of the haemoproteid parasites hitherto described from the avian genus Passer is reviewed. It is concluded that 1 species only is valid Haemoproteus passeris Kruse (1890), all other species being designated as synonyms. From material obtained from Passer domesticus a re-description is given of H. passeris which has shown to exhibit a wide range of morphological forms. The reasons for this are discussed. Schizogonic stages are described for the first time for this species, and evidence is presented which suggests that H. passeris does not belong to the sub-genus Parahaemoproteus. Schizogonic stages previously considered to be from Passer spp. probably originated from birds of another genus and family. H. passeris appears to be restricted to the avian genus Passer in which it has a world-wide distribution.