Shell of Difflugia acuminata: an agglutinated test made up of mineral particles glued together with secretions from within the cell
Testate amoebae (formerly thecamoebians, Testacea or Thecamoeba) are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae in the presence of a 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.
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.[1]
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 anastomose.[2]
Testate amoebae can be found in most freshwater environments, including lakes, rivers, cenotes,[3] as well as mires and soils.
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 bioindicators and paleoclimate proxies in recent years.[4]
^B., Scott, D. (2001). Monitoring in coastal environments using Foraminifera and Thecamoebian indicators. Medioli, F. S., Schafer, Charles T. Cambridge: Cambridge University Press. ISBN 978-0521561730. OCLC 70724931.{{cite book}}: CS1 maint: multiple names: authors list (link)
^Kosakyan, Anush; Gomaa, Fatma; Lara, Enrique; Lahr, Daniel J.G. (2016). "Current and future perspectives on the systematics, taxonomy and nomenclature of testate amoebae". European Journal of Protistology. 55 (Pt B): 105–117. doi:10.1016/j.ejop.2016.02.001. hdl:11380/1302106. PMID 27004416.
^Sigala, Itzel; Lozano-García, Socorro; Escobar, Jaime; Pérez, Liseth; Gallegos-Neyra, Elvia (2016-06-28). "Testate Amoebae (Amebozoa: Arcellinida) in Tropical Lakes of Central Mexico". Revista de Biología Tropical. 64 (1): 377–397. doi:10.15517/rbt.v64i1.18004. ISSN 2215-2075. PMID 28862826.
^Mitchell, Edward A. D.; Charman, Daniel J.; Warner, Barry G. (2008-08-01). "Testate amoebae analysis in ecological and paleoecological studies of wetlands: past, present and future" (PDF). Biodiversity and Conservation. 17 (9): 2115–2137. doi:10.1007/s10531-007-9221-3. ISSN 0960-3115. S2CID 27912982.
Testateamoebae (formerly thecamoebians, Testacea or Thecamoeba) are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae...
Arcellinid testateamoebae or Arcellinida, Arcellacean or lobose testateamoebae are single-celled protists partially enclosed in a simple test (shell)...
referred to as "testateamoebae", grow a shell around the cell made from organic or inorganic material. Slime molds, which are amoebae capable of producing...
such as Jahn, who grouped all amoebae with granular pseudopodia together, but most split the lobose amoebae into testate Testacealobosia and naked Gymnamoebia...
Centropyxis is a genus of lobose testateamoebae (Amoebozoa), including the species Centropyxis aculeata. WoRMS (2010). "Centropyxis Stein, 1857". World...
g. diatom frustules) and are thus commonly referred to as testateamoebae or shelled amoebae. Difflugia are particularly common in marshes and other freshwater...
arcellinid testateamoebae and the sole family of the infraorder Hyalospheniformes. Commonly referred to as "hyalospheniids", these lobose amoebae are characterized...
are still not entirely clear. Foraminifera are closely related to testateamoebae. The most striking aspect of most foraminifera are their hard shells...
Free-living amoebae may be "testate" (enclosed within a hard shell), or "naked" (also known as gymnamoebae, lacking any hard covering). The shells of testate amoebae...
It contains all amoebae of the families Microcoryciidae, which was previously regarded as Arcellinida (an order of testateamoebae), and Trichosphaeriidae...
Arcella is a genus of testateamoebae in the order Arcellinida, usually found in freshwaters and mosses, and rarely in soils. A key characteristic of...
Certesella is a genus of testateamoebae belonging to the family Hyalospheniidae. It is characterized by a test that presents two symmetrical holes near...
Thecofilosea is a class of unicellular testateamoebae belonging to the phylum Cercozoa. They are amoeboflagellates, organisms with flagella and pseudopodia...
Greek αλάβαστρος (alábastros) 'alabaster') is a genus of arcellinid testateamoebae belonging to the family Hyalospheniidae. It contains species with an...
include: Tests or frustules (i.e. shells) of diatoms, Radiolaria, and testateamoebae. Silica phytoliths in the cells of many plants, including Equisetaceae...
Nebela is a diverse genus of testateamoebae of cosmopolitan distribution, belonging to the family Hyalospheniidae. They are "prey agglutinated" or "kleptosquamic"...
Cryptodifflugia leachi is an aquatic species of testateamoebae discovered in 2006 in Canada, living in bottom sediment from wetlands at the base of the...
(from Latin planus 'flat', and carina 'keel') is a genus of arcellinid testateamoebae belonging to the family Hyalospheniidae. It was created in 2016 to...
Cryptodifflugiidae is a family of arcellinid testateamoebae. Members of this family are conopodous (with conical pseudopods) amoebae with the body in a clear, usually...
Pseudocucurbitella is a genus of freshwater testateamoebae of the order Arcellinida. Its shell is agglutinated, ovoid, with a round crossection and a...
Lara, E. (2014). "One Alga to Rule them All: Unrelated Mixotrophic TestateAmoebae (Amoebozoa, Rhizaria and Stramenopiles) Share the Same Symbiont (Trebouxiophyceae)"...
Erugomicula is a genus of testate lobose amoebae found in the order Arcellinida. It was described in 2021 and tentatively placed in the family Hyalospheniidae...
Meisterfeldia is a genus of arcellinid testateamoebae erected in 2016 that unites several new species as well as old species previously found in the...
foraminiferans, including xenophyophoreans and komokiaceans, Gromia, and testateamoebae. The pellets are ovoid (egg-shaped), brownish in color, and on average...
green euglenids, various ciliates (such as the folliculinids, various testateamoebae and foraminifera. The surfaces of a variety of protozoa are covered...
O. W. (1 January 1962). "The Abundance and Micro-Distribution of TestateAmoebae (Rhizopoda:Testacea) in Sphagnum". Oikos. 13 (1): 35–65. doi:10.2307/3565062...
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