A subphylum of spore-producing Protozoa containing the two classes Myxosporidea and Microsporidea. Myxosporidea contains the three orders Myxosporida, Actinomyxida, and Helicosporida. Microsporida is the only order in the class Microsporidea. Cnidospora are parasites of cells and tissues of invertebrates, fishes, a few amphibians, and turtles.