This article may be too technical for most readers to understand.(June 2023)  | 
| Monothalamea | |
|---|---|
|   | |
| Image of a deep sea xenophyophore | |
|  Scientific classification   | |
| Domain: | Eukaryota | 
| Clade: | Diaphoretickes | 
| Clade: | Sar | 
| Clade: | Rhizaria | 
| Phylum: | Retaria | 
| Subphylum: | Foraminifera | 
| Class: |  Monothalamea  Haeckel, 1862, [1] emend. Pawlowski et al., 2013 [2]  | 
| Orders and subtaxa incertae sedis [3] | |
  | |
"Monothalamea" is a grouping of foraminiferans, traditionally consisting of all foraminifera with single-chambered tests. Recent work has shown that the grouping is paraphyletic, and as such does not constitute a natural group; nonetheless, the name "monothalamea" continues to be used by foraminifera workers out of convenience. [4]
"Monothalamea" traditionally contains two groups, neither of which is currently considered to be monophyletic:
Recent molecular evidence has revealed that the deep-sea xenophyophores are in fact agglutinated, single-chambered foraminifera. [5] Molecular evidence has also revealed that the freshwater protist Reticulomyxa is in fact a naked, testless foraminifera, and as such it has been included with "monothalameans" in scientific discussion. [4] [6]
A 2013 molecular study using small subunit rDNA concluded that known "monothalameans" made up at least 22 distinct living clades from marine environments with an additional four clades from freshwater eDNA. [4]