Phylogeny of the Microsporidia

Most modern microsporidian species descriptions include detailed microscopic and ultra structural images, and many of the more recent descriptions also include a small subunit ribosomal DNA (ssrDNA) sequence analysis. Characters that have traditionally been used for taxonomic purposes include phenotypic characters, developmental characters, and ecological characters. While these characters provide a convenient and important means for classifying newly discovered species, the phylogenetic significance of taxonomic groupings based on these characters is not clear. Microsporidian classification should be based on the development of the vegetative form at the family level, the process of spore formation at the generic level, and the form of the spores at the species level. The molecular data provide an excellent means for the identification of a species and for developing phylogenies. Many descriptions of microsporidian genera and species include an ssrDNA sequence, making it much easier for the author to determine the new species' taxonomic position.