Bivalvulida

Bivalvulida is an order of myxosporean parasites which contains a number of species which cause economically significant losses to aquaculture and fisheries, such as Myxobolus cerebralis and Ceratomyxa shasta. The Myxosporean stages of members of the bivalvulida are characterised by their two spore valves (hence the name), which meet in a "suture line" which encircles the spore. They usually contain two polar capsules, but species have been reported which contain either one or four.

==Taxonomy and systematics== The order Bivalvulida is composed of three suborders and thirteen families. Suborder Platysporina Kudo, 1919 Myxobolidae Thélohan, 1892 Suborder Sphaeromyxina Lom & Noble, 1984 Sphaeromyxidae Lom & Noble, 1984 Suborder Variisporina Lom & Noble, 1984 Auerbachiidae Alatasporidae Shulman, Kovaleva & Dubina, 1979 Ceratomyxidae Doflein, 1899 Chloromyxidae Thélohan, 1892 Coccomyxidae Léger & Hesse, 1907 Fabesporidae Naidenova & Zaika, 1969 Myxidiidae Thélohan, 1892 Myxobilatidae Shulman, 1953 Ortholineidae Lom & Noble, 1984 Parvicapsulidae Shulman, 1953 Sinuolineidae Shulman, 1959 Sphaerosporidae Davis, 1917