Problems in the Systematics of the “Sporozoa”*

The taxonomy of the so‐called Sporozoa is reviewed, and it is concluded that the group is polyphyletic and should be split into the following independent taxa: (1) The subphylum EUSPORA subph. nov., members of which have simple spores without polar filaments; this subphylum contains the classes TELOSPORASIDA Schaudinn, 1900 and HAPLO‐SPORASIDA Caullery and Mesnil, 1899; (2) the subphylum CNIDOSPORA Doflein, 1901, members of which have spores containing 1 or more polar filaments; (3) the class PIRO PLASMASIDA Wenyon, 1926, members of which have no spores, are parasitic in vertebrate erythrocytes and are heter‐oxenous; and (4) the class TOXOPLASMASIDA Biocca, 1957 emend., members of which have no spores, have cysts or pseudocysts, and are monoxenous parasites of vertebrates; the latter two groups are not assigned to subphyla but are considered appendages to the Protozoa. A classification to suborders is given of the Euspora.