| Hemimastigophora | |
|---|---|
 | |
| Hemimastix amphikineta, redrawn from Foissner et al., 1988[2] | |
Scientific classification | |
| Domain: | Eukaryota |
| Clade: | Diaphoretickes (?) |
| Supergroup: | Disparia |
| Clade: | Membrifera |
| Phylum: | Hemimastigophora Foissner, Blatterer & Foissner 1988 sensu Cavalier-Smith 1993[1]: 379 |
| Class: | Hemimastigea Foissner, Blatterer & Foissner 1988 |
| Order: | Hemimastigida Foissner, Blatterer & Foissner 1988 |
| Families | |
| Synonyms | |
| |
Hemimastigophora is a group ofsingle-celledeukaryotic organisms including theSpironematellidae, first identified in 1988,[1][2][3] and theParamastigidae. Over the next 30 years, different authors proposed placing these organisms in various branches of theeukaryotes.[2][4] In 2018 Lax et al. reported the first genetic information for Spironemidae, and suggest that they are from an ancient lineage of eukaryotes which constitute a separateclade from all other eukaryotickingdoms.[3][4] It may be related to theTelonemia.[5]
Hemimastigophora was established in 1988 by Foissner et al., as a newphylum with a single family, Spironemidae.[1] Its placement on the eukaryotetree of life was unclear, but the authors suggested that the structure of itspellicle andcell nucleus indicated a close relationship withEuglenozoa.[2] For 30 years after the description of the group, no genetic information was available. During that time, researchers proposed that it should be classified in, or near, an assortment of other groups, including thealveolates,apusomonads,ancyromonads, andRhizaria.[3][4]
In an article published in 2018, Lax et al. announced that a new hemimastigophoran species,Hemimastix kukwesjijk, had been discovered in aNova Scotian soil sample, and successfully cultivated in the laboratory. A second hemimastigophoran, a new species ofSpironema, was found in the same sample.Phylogenomic analyses of the two organisms suggest that Hemimastigophora is a very ancient lineage, which diverged from the other eukaryotes at such an early date that the group should be classified at the supra-kingdom level.[3][4]
The 2024 study revealed the enigmaticMeteora sporadica to be also related to Hemimastigophora.[6]
The hemimastigote classification, as of 2022:[7]
