Single chamber (monothalamous) test with an organic or agglutinated wall; the group comprises all genera traditionally included into the orders Allogromiida and Astrorhizida, as well as the deep-sea giant Xenophyophorea; it also includes freshwater and marine “naked” amoeboid species and environmental clades with unknown morphology (see Pawlowski et al. 2011); the diversity of this mainly unfossilized group is poorly known and has been largely overlooked in micropaleontologically oriented foraminiferal research.
Remarks: The group is paraphyletic, i.e. it comprises the ancestor of all foraminifera including monothalamous and polythalamous groups. Further phylogenetic analyses are needed to subdivide it into independent monothalamous lineages.
Source: Pawlowski J., Holzmann M., Tyszka J., 2013. New supraordinal classification of Foraminifera: Molecules meet morphology. Marine Micropaleontology, available online 17 April 2013, http://dx.doi.org/10.1016/j.marmicro.2013.04.002