"Monothalamea" is a grouping of
foraminifera
Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...
ns, traditionally consisting of all foraminifera with single-chambered
tests
Test(s), testing, or TEST may refer to:
* Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities
Arts and entertainment
* ''Test'' (2013 film), an American film
* ''Test'' (2014 film) ...
. Recent work has shown that the grouping is
paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
, and as such does not constitute a natural group; nonetheless, the name "monothalamea" continues to be used by foraminifera workers out of convenience.
Classification
"Monothalamea" traditionally contains two groups, neither of which is currently considered to be
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
:
* "
Allogromiida" traditionally consists of all foraminifera which lack a mineralised test, instead having a test of tectin. Recent work has shown that this grouping is
paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
.
* "Astrorhizida" traditionally consists of all foraminifera with single-chambered, agglutinated tests. Recent work has shown that this grouping is
polyphyletic
A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...
, as agglutinated tests have evolved from proteinaceous tests multiple times throughout foraminiferal evolution.
Recent molecular evidence has revealed that the deep-sea
xenophyophores are in fact agglutinated, single-chambered foraminifera. Molecular evidence has also revealed that the freshwater
protist
A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...
''
Reticulomyxa'' is in fact a naked, testless foraminifera, and as such it has been included with "monothalameans" in scientific discussion.
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.
References
Further reading
*Gubbay, S., Baker, M., Bettn, B., Konnecker, G. (2002)
"The offshore directory: Review of a selection of habitats, communities and species of the north-east Atlantic" pp. 74–77.
*
NOAA
The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploratio ...
Ocean Explorer
"Windows to the deep exploration: Giants of the protozoa" p. 2.
External links
{{Taxonbar, from1=Q16608712, from2=Q632686
Foraminifera classes
Extremophiles
Taxa named by Ernst Haeckel