The gametogony and the tissue schizogony of Parahaemoproteus desseri are described in the natural host: Psittacula roseata; the schizonts develop in muscle fibres; they are large (up to 900 micrometer) and often sausage shaped with pseudo-septa. Experimental sporogony was studied in laboratory bred Culicoides nubeculosus (Ceratopogonidae). Oocysts are small and give rise to a small number of sporozoites. The morphological characteristics of the schizonts of our Parahaemoproteus are very similar to those of schizonts of Arthrocystis galli and therefore it is possible that the two genera are synonymous.