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{{Short description|Group of amoebae with shells}}
[[File:Difflugia acuminata.jpg|thumb|300x300px|Shell of ''Difflugia acuminata'': an agglutinated test made up of mineral particles glued together with secretions from within the cell.]]▼
{{redir|Thecamoebians|the family of Amoebozoa|Thecamoebidae|the genus in Thecamoebidae|Thecamoeba}}
'''Testate amoebae''' (formerly '''thecamoebians''', [[Testacea]] or Thecamoeba) are a [[polyphyletic]] group of unicellular [[ameboid]] [[protist]]s, which differ from '''naked amoebae''' in the presence of a [[test (biology)|test]] that partially encloses the cell, with an aperture from which the [[pseudopodia]] emerge, that provides the amoeba with shelter from predators and environmental conditions.▼
▲[[File:Difflugia acuminata.jpg|thumb|
▲'''Testate amoebae''' (formerly '''thecamoebians''', [[Testacea]] or Thecamoeba) are a [[polyphyletic]] group of unicellular [[
The test of some species is produced entirely by the amoeba and may be organic, siliceous or calcareous depending on the species ('''autogenic tests'''), whereas in other cases the test is made up of particles of sediment collected by the amoeba which are then agglutinated together by secretions from within the cell ('''xenogenic tests'''). A few taxa (Hyalosphenidae) can build either type, depending on the circumstances and availability of foreign material.<ref>{{Cite book|url=https://www.worldcat.org/oclc/70724931|title=Monitoring in coastal environments using Foraminifera and Thecamoebian indicators|last=B.|first=Scott, D.|date=2001|publisher=Cambridge University Press|others=Medioli, F. S., Schafer, Charles T.|isbn=0521561736|location=Cambridge|oclc=70724931}}</ref>▼
▲The test of some species is produced entirely by the amoeba and may be organic, siliceous or calcareous depending on the species ('''autogenic tests'''), whereas in other cases the test is made up of particles of sediment collected by the amoeba which are then agglutinated together by secretions from within the cell ('''xenogenic tests'''). A few taxa (
The assemblage referred to as "testate amoebae" is actually composed of several, unrelated groups of organisms. However, some features they all share that have been used to group them together include the presence of a test (regardless of its composition) and pseudopodia that do not [[Anastomosis|anastomose]].<ref name=":1">{{Cite journal|last=Kosakyan|first=Anush|last2=Gomaa|first2=Fatma|last3=Lara|first3=Enrique|last4=Lahr|first4=Daniel J.G.|title=Current and future perspectives on the systematics, taxonomy and nomenclature of testate amoebae|url=http://linkinghub.elsevier.com/retrieve/pii/S0932473916300013|journal=European Journal of Protistology|volume=55|pages=105–117|doi=10.1016/j.ejop.2016.02.001}}</ref>▼
▲The assemblage referred to as "testate amoebae" is actually composed of several, unrelated groups of organisms. However, some features they all share that have been used to group them together include the presence of a test (regardless of its composition) and pseudopodia that do not [[Anastomosis|anastomose]].<ref name=":1">{{Cite journal|
Testate amoebae can be found in most freshwater environments, including lakes, rivers, [[Cenote|cenotes]]<ref>{{Cite journal|last=Sigala|first=Itzel|last2=Lozano-García|first2=Socorro|last3=Escobar|first3=Jaime|last4=Pérez|first4=Liseth|last5=Gallegos-Neyra|first5=Elvia|date=2016-06-28|title=Testate Amoebae (Amebozoa: Arcellinida) in Tropical Lakes of Central Mexico|url=https://revistas.ucr.ac.cr/index.php/rbt/article/view/18004|journal=Revista de Biología Tropical|language=en|volume=64|issue=1|pages=377–397|doi=10.15517/rbt.v64i1.18004|issn=2215-2075}}</ref>, as well as [[Mire|mires]] and soils.▼
▲Testate amoebae can be found in most freshwater environments, including lakes, rivers, [[
The strong and resistant nature of the tests allows them to be preserved long after the amoeba has died. These characteristics, along with the sensitivity that some species display to changes in environmental conditions (such as temperature, pH, and conductivity), has sparked their use as [[
== Gallery ==
{{biomineralization sidebar|exoskeletons}}
<gallery mode=packed heights=205px style="float:left;">
File:Amoeba proteus 2.jpg|Naked amoeba (i. e. not testate) showing food vacuoles and ingested diatom
File:Arcella sp.jpg|Shell or test of a [[testate amoeba]], ''[[Arcella]]'' sp.
File:Collection Penard MHNG Specimen 533-2-1 Pamphagus granulatus.tif|[[wiktionary:xenogenic|Xenogenic]] testate amoeba covered in diatoms (from [https://commons.wikimedia.org/wiki/Commons:P%C3%A9nard_project Penard's Amoeba Collection])
</gallery>
{{clear left}}
<gallery mode=packed heights=200px style="float:left;">
File:Euglypha tuberculata - Testate amoeba - 160x (14997753245).jpg| ''Euglypha tuberculata'', a species with a siliceous autogenic test
</gallery>
{{clear}}
▲The strong and resistant nature of the tests allows them to be preserved long after the amoeba has died. These characteristics, along with the sensitivity that some species display to changes in environmental conditions (such as temperature, pH, and conductivity), has sparked their use as [[Bioindicator|bioindicators]] and [[Proxy (climate)|paleoclimate proxies]] in recent years.<ref>{{Cite journal|last=Mitchell|first=Edward A. D.|last2=Charman|first2=Daniel J.|last3=Warner|first3=Barry G.|date=2008-08-01|title=Testate amoebae analysis in ecological and paleoecological studies of wetlands: past, present and future|url=https://link.springer.com/article/10.1007/s10531-007-9221-3|journal=Biodiversity and Conservation|language=en|volume=17|issue=9|pages=2115–2137|doi=10.1007/s10531-007-9221-3|issn=0960-3115}}</ref>[[File:Euglypha tuberculata - Testate amoeba - 160x (14997753245).jpg|thumb|300x300px|''Euglypha tuberculata'', a species with a siliceous autogenic test.]]
▲[[File:Arcella sp (discoides) - 400x (14739877768).jpg|thumb|300x300px|The autogenic test of ''Arcella discoides'', made up of organic plates.]]
▲[[File:Cyphoderia ampulla - Testate amoeba - 160x (14997391862).jpg|thumb|300x300px|Shell of ''Cyphoderia ampulla'', composed of circular, siliceous plates produced by the amoeba.]]
== Taxonomy and classification ==
Testate amoebae are a polyphyletic assemblage. The main testate amoebae groups are the [[Lobosa|lobose]] [[Tubulinea]], which include [[Arcellinida]], [[Difflugina]] and [[Phryganellina]] (within the [[Amoebozoa]]),<ref>Ralf Meisterfeld: ''Arcellinida'', In: John J. Lee, Gordon F. Leedale, Phyllis Bradbury (Hrsg.): Illustrated Guide to the Protozoa, 2nd Edition. Vol. 2, Society of Protozoologists, Lawrence, Kansas 2000, {{ISBN|1-891276-23-9}}, pp. 827-860</ref>
=== Order Arcellinida ===▼
▲=== Order Arcellinida ===
{{div col
;;Family Arcellidae
;;Family Netzeliidae
;;Family Hyalospheniidae
;;Family Microchlamyiidae
;;Family Plagiopyxidae
;;Family Cryptodifflugiidae
;;Family Microcoryciidae
;;Family Phryganellidae
;;Family Lamtopyxidae
;;Family Distomatopyxidae
;;Family Paraquadrulidae
;;Family Centropyxidae
;;Family Trigonopyxidae
;;Incertae sedis
{{div col
=== Order Euglyphida ===
{{col-begin|width=90%}}
{{col-break}}
;;Family Euglyphidae
;;Family Trinematidae
;;Family Sphenoderiidae
{{col-break}}
;;Family Assulinidae
;;Family Cyphoderiidae
{{col-break}}
;;Family Paulinellidae
;;Incertae sedis
{{col end}}
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{{col-begin|width=90%}}
{{col-break}}
;;Family Chlamydophryidae
;;Family Pseudodifflugiidae
{{col-break}}
;;Family Psammonobiotidae
{{col-break}}
;;Incertae sedis
{{col end}}
Line 206 ⟶ 221:
{{col-break}}
;;Family Amphitremidae
;;Family Diplophryidae
{{col-break}}
;;Family Amphifilidae
;;Family Sorodiplophryidae
{{col end}}
=== Unclassified testate amoebae ===
{{div col
{{div col end}}
The following table includes a few examples of testate amoebae genera, and reflects their position within the classification by Adl ''et al.'' (2012),<ref name=":0" />
▲The following table includes a few examples of testate amoebae genera, and reflects their position within the classification by Adl ''et al.'' (2012)<ref name=":0" />, where five supergroups ([[Amoebozoa]], [[Opisthokont|Opisthokonta]], [[Excavata]], [[SAR supergroup|SAR]] and [[Archaeplastida]]) were proposed to classify all [[Eukaryote|eukaryotes]]. This classification purposefully avoids the use of [[Carl Linnaeus|Linnaean]] higher category names (phylum, class, order, family). While it has been noted that the names that Adl ''et al.'' provide for the clades may result confusing or uninformative regarding the relative degree of [[Phenotype|phenotypic]] distinctiveness amongst groups when used in isolation<ref>{{Cite journal|last=Ruggiero|first=Michael A.|last2=Gordon|first2=Dennis P.|last3=Orrell|first3=Thomas M.|last4=Bailly|first4=Nicolas|last5=Bourgoin|first5=Thierry|last6=Brusca|first6=Richard C.|last7=Cavalier-Smith|first7=Thomas|last8=Guiry|first8=Michael D.|last9=Kirk|first9=Paul M.|date=2015-04-29|title=A Higher Level Classification of All Living Organisms|url=http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119248|journal=PLOS ONE|volume=10|issue=4|pages=e0119248|doi=10.1371/journal.pone.0119248|issn=1932-6203}}</ref>, this system avoids creating superfluous ranks where unnecessary and provides stable group names that can be retained even when a group is moved to a different [[Lineage (evolution)|lineage]], as is often the case with protists, as their classification remains in constant review.<ref name=":0" />
{| class="wikitable"
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| rowspan="3" |[[Arcellinida]]
|Arcellina
| colspan="4" |<small>''Amphizonella -
|-
|Difflugina
| colspan="4" |''<small>Bullinularia
''<small>Plagiopyxis
|-
|Phryganellina
| colspan="4" |''<small>[[Cryptodifflugia]]
|-
|Discosea
Line 252 ⟶ 265:
|Labyrinthulomycetes
|Amphitremida
| colspan="4" |''<small>[[Amphitrema]]
|-
| rowspan="7" |Rhizaria
Line 259 ⟶ 272:
| rowspan="2" |Cryomonadida
|Rhizaspididae
| colspan="2" |''<small>Capsellina
|-
|Ventricleftida
| colspan="2" |''<small>Ventrifissura
|-
| rowspan="5" |Imbricatea
Line 268 ⟶ 281:
| rowspan="5" |[[Euglyphida]]
|Euglyphidae
|''<small>[[Euglypha]]
|-
|Assulinidae
|''<small>Assulina
|-
|Trinematidae
|''<small>Corythion
|-
|Cyphoderidae
|''<small>Campascus
|-
|Paulinellidae
|''<small>Ovulinata
|}Traditionally, those species that form large networks of anastomosing [[pseudopodia]], despite some of them having tests, are not counted amongst testate amoebae; this comprises genus ''[[Gromia]]'' and the [[Foraminifera]] (both in Rhizaria).<ref name=":1" />
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The [[Thecamoebida]] (Amoebozoa), with the genus ''[[Thecamoeba]]'', despite their name, do not have tests.
Euglyphid testate amoebae are closely related to the [[Foraminifera]].<ref>{{
== External links ==
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