Fig. 1

Main morphological features of blood stages, which are used for identification of families of haemosporidian (Haemosporida) parasites (a–i). Mature gametocytes (a, b, g–i) and meronts (c–f) of Plasmodium (a–c), Garnia (d, e), Fallisia (f), Haemoproteus (g) and Leucocytozoon (h, i) parasites belonging to the families Plasmodiidae (a–c), Garniidae (d–f), Haemoproteidae (g) and Leucocytozoidae (h, i). Note presence of malarial pigment in species of Plasmodiidae (a–c) and Haemoproteidae (g) and its absence in species of Garniidae (d–f) and Leucocytozoidae (h, i). Macrogametocytes (a, g, h) and microgametocytes (b, i) are readily distinguishable due to presence of sexually dimorphic features. Common avian intracellular non-haemosporidian parasites (j–l) are shown for comparison with haemosporidians. These are Isospora (synonym Atoxoplasma) (j), Hepatozoon (k) and Babesia (l). Long simple arrows—nuclei of parasites. Simple arrowhead—pigment granules. Triangle arrowheads—developing merozoites. Long simple wide arrow—nucleolus. Simple wide arrowheads—host cell nuclei. Short simple wide arrow—cytoplasm of host cell. Scale bar = 10 µm. Explanations are given in the text