"Monothalamea" is a grouping offoraminiferans, traditionally consisting of all foraminifera with single-chamberedtests. Recent work has shown that the grouping isparaphyletic, 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 bemonophyletic:
"Allogromiida" traditionally consists of all foraminifera which lack a mineralised test, instead having a test of tectin. Recent work has shown that this grouping isparaphyletic.
"Astrorhizida" traditionally consists of all foraminifera with single-chambered, agglutinated tests. Recent work has shown that this grouping ispolyphyletic, as agglutinated tests have evolved from proteinaceous tests multiple times throughout foraminiferal evolution.[4]
Recent molecular evidence has revealed that the deep-seaxenophyophores are in fact agglutinated, single-chambered foraminifera.[5] Molecular evidence has also revealed that the freshwaterprotistReticulomyxa 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 usingsmall subunitrDNA concluded that known "monothalameans" made up at least 22 distinct living clades from marine environments with an additional four clades from freshwatereDNA.[4]
