Synopsis of the species of the genus Sphaeromyxa Thélohan, 1892 (Myxosporea: Bivalvulida: Variisporina: Sphaeromyxidae).

Sphaeromyxa spp. are parasites of marine fishes, infecting the gall-bladders or bile ducts. The spores of these species possess characteristic ribbon-like polar filaments, a unique character among myxozoans. This unique character is also a synapomorphy consistent with estimates of phylogeny for this group which forms a lineage distinct from other myxozoans. There are 49 nominal species of Sphaeromyxa Thélohan, 1892 for which a synopsis is provided, reporting spore dimensions, spore shape, locality, and host species. A line drawing is also provided for each species.