Mitosporidium

Mitosporidium
Scientific classification
Kingdom:	Fungi
Phylum:	Rozellomycota
Class:	Microsporidia
Genus:	Mitosporidium Haag et al., 2015

Mitosporidium is a genus of microsporidian parasites. The genus was erected in 2014 ^[1] but, for nomenclatural reasons, the taxon was valid only in 2015. ^[2]

In contrast to most members of the Microsporidia, species in Mitosporidium have retained ancestral features such as mitochondrial respiration. However, they have a spore stage with a polar tube which is a unique characteristic of the Microsporidia, and they are intracellular parasites.

Taxonomic placement

Mitosporidium is sometimes referred to as "microsporidia‐like protist" or "the earliest branching microsporidian". ^[3] In the most recent (2024) classification of Fungi, Mitosporidium was considered to be a member of the Rozellomycota, with no more precise placement. ^[4]

Species

The mitogenome of Mitosporidium sp. 467

A phylogenetic tree of species of Mitosporidium and their closer relatives

Until 2025, the only known species of the genus was Mitosporidium daphniaeHaag et al., 2015, a parasite infecting the hindgut epithelium of the freshwater crustacean Daphnia . ^[1]

In 2025, researchers studying land flatworms from Northern Ireland reported genetic evidence of two additional species of Mitosporidium. ^[5] Each land flatworm species was found to harbour its own Mitosporidium species: Australoplana sanguinea contained Mitosporidium sp. JL472, while Kontikia andersoni contained Mitosporidium sp. JL467. For nomenclatural reasons, these species could not be formally assigned binomial names. For both new species, the gene content of the mitogenome and the cluster of nuclear ribosomal RNA genes were described. However, it has not yet been fully determined whether the microsporidia are parasites of the land flatworms themselves or of the earthworms that constitute their prey. ^[5]

References

1. Haag, Karen L.; James, Timothy Y.; Pombert, Jean-François; Larsson, Ronny; Schaer, Tobias M. M.; Refardt, Dominik; Ebert, Dieter (2014-10-28). "Evolution of a morphological novelty occurred before genome compaction in a lineage of extreme parasites". Proceedings of the National Academy of Sciences. 111 (43): 15480–15485. doi:10.1073/pnas.1410442111. ISSN   0027-8424.
2. "Correction for Haag et al., Evolution of a morphological novelty occurred before genome compaction in a lineage of extreme parasites". Proceedings of the National Academy of Sciences. 112 (10). 2015-03-10. doi:10.1073/pnas.1502848112. ISSN   0027-8424. PMC   4364216 . PMID   25713126.
3. Bass, David; Czech, Lucas; Williams, Bryony A. P.; Berney, Cédric; Dunthorn, Micah; Mahé, Frederic; Torruella, Guifré; Stentiford, Grant D.; Williams, Tom A. (2018). "Clarifying the relationships between Microsporidia and Cryptomycota". Journal of Eukaryotic Microbiology. 65 (6): 773–782. doi:10.1111/jeu.12519. ISSN   1066-5234. PMC   6282948 . PMID   29603494.
4. Wijayawardene, Nalin N.; Hyde, Kevin D.; Mikhailov, Kirill V.; Péter, Gábor; Aptroot, André; Pires-Zottarelli, Carmen L. A.; Goto, Bruno T.; Tokarev, Yuri S.; Haelewaters, Danny; Karunarathna, Samantha C.; Kirk, Paul M.; de A. Santiago, André L. C. M.; Saxena, Ramesh K.; Schoutteten, Nathan; Wimalasena, Madhara K. (2024). "Classes and phyla of the kingdom Fungi". Fungal Diversity. 128 (1): 1–165. doi: 10.1007/s13225-024-00540-z . ISSN   1878-9129.
5. Gastineau, Romain; Murchie, Archie K.; Winsor, Leigh; Justine, Jean-Lou (2025). "An Irish cocktail of flatworm, earthworm and parasite DNAs: genomics of invasive land flatworms (Geoplanidae) reveal infestations by two new Mitosporidium species (Microsporidia)". Parasite. 32: 67. doi:10.1051/parasite/2025060. ISSN   1776-1042. PMC   12534020 . PMID   41105848.