Arcella is a genus of

testate amoebae 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 (biology), test that partially encloses the cell, with an apert ...

in the order Arcellinida, commonly found in

ponds A pond is a small, still, land-based body of water formed by pooling inside a depression, either naturally or artificially. A pond is smaller than a lake and there are no official criteria distinguishing the two, although defining a pond t ...

wetlands A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

, and

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which

pseudopods A pseudopod or pseudopodium (: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filaments and ...

are extended. Recognized for its broad ecological adaptability, ''Arcella'' has been described as "probably the most ecologically successful Arcellinid taxon", with several species exhibiting a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

across diverse environments. Arcella conica

History and classification

The genus Arcella was established in 1830 by the German zoologist

C. G. Ehrenberg Christian Gottfried Ehrenberg (19 April 1795 – 27 June 1876) was a German naturalist, zoologist, botanist, comparative anatomist, geologist, and microscopist. He is considered to be one of the most famous and productive scientists of his time. ...

, who designated ''Arcella vulgaris'' as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

. Over time, numerous species were added to the genus, and by the early 21st century, approximately 51 nominal species, 71 varieties, and 27 distinct forms had been recognized. In 2021, González-Miguéns et al. conducted a comprehensive revision of the family Arcellidae, using

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

to uncover evolutionary relationships within the group. Their findings led to the reclassification of six ''Arcella'' species, which were transferred to the newly established genus

Galeripora ''Galeripora'' is a genus of testate amoebae in the family Arcellidae, closely related to '' Arcella''. Both genera share a proteinaceous organic shell, but ''Galeripora'' species are distinguished by pores surrounding their central circular aper ...

. This genus was distinguished by the presence of pores surrounding the aperture of the test and a thin layer of organic material partially covering the shell’s surface. Since then, several other species previously classified in ''Arcella'' have been transferred to ''Galeripora''.

Anatomy

Species of ''Arcella'' are typically enclosed in a domed or umbrella-shaped

test 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) ...

(shell) with a single central aperture. This test is composed of secreted proteinaceous material, arranged in hexagonal units known as "areoles." Unlike many other genera in the order Arcellinida, ''Arcella'' species do not incorporate scavenged materials, such as mineral particles or diatoms, in their shells. The shape of the shell varies from one species to the next, and sizes range from less than 50 μm to well over 300 μm. When newly-formed, ''Arcella'' tests are transparent or pale yellow in colour. As shells age, they gradually darken, becoming nearly brown due to the progressive deposition of

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

and

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

compounds.Ralf Meisterfeld and Edward Mitchell (2008)
"''Arcella'' Ehrenberg 1832"
Most species of ''Arcella'' have two cell nuclei, but some are multinucleate. Cells do not entirely fill the test in which they live, but are connected to the inner surface by thin strands of cytoplasm known as epipodia.

Nutrition and distribution

''Arcella'' inhabit a wide range of

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

environments, including pools,

eutrophic Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

waters,

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

es,

es, slow-moving streams, and wet foliage. A few species can also be found in soils. While most species are associated with fresh water, some have been found in coastal salt marshes, and saline lakes. Like other amoebae, ''Arcella'' use their pseudopods to take in food. They feed on bacteria,

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s, fungi,

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and the ...

s and small

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

s. Most species are cosmopolitan, meaning they occur worldwide. However, some species have more restricted distributions'','' such as ''A. brasiliensis, A. peruviana'' and ''A. gandalfi'', which are endemic to South America.

Species

*''

Arcella apicata Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Schaudinn, 1898 *''

Arcella brasiliensis Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Cunha, 1913
Microworld Arcella *'' Arcella conica'' (Playfair, 1918) *''

Arcella corona Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Van Oye, 1926 * '' Arcella costata'' Ehrenberg, 1847 * ''

Arcella crenata Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Playfair, 1917 * ''

Arcella crenulata Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in Pond, ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which Pseudopodia, p ...

'' Deflandre, 1928 * ''

Arcella euryhalina Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Useros et al., 2023 *'' Arcella excavata'' Cunningham, 1919
*''

Arcella formosa Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Nicholls, 2005 * ''Arcella gandalfi'' Féres et al., 2016 Microworld
/ref> *'' Arcella gibbosa'' Penard, 1890 *''

Arcella grospietschi Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Stepanek, 1963 *''

Arcella guadarramensis Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' González-Miguéns & Lara, 202 *'' Arcella hemisphaerica'' Perty, 1852 * '' Arcella intermedia'' (Deflandre, 1928) Tsyganov & Mazei 2006 * ''

Arcella jeanneli Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Virieux, 1913 * ''

Arcella lichenophila Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Decloitre, 1965 * ''

Arcella lobostoma Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Deflandre, 1929 * ''

Arcella manipurensis Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Chattopadhyay & Das, 2003 * ''

Arcella marginata Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Daday, 1905 * '' Arcella mitrata'' Leidy, 1876 * '' Arcella mitriformis'' (Deflandre, 1928) Siemensma, 2025 * '' Arcella multilobata'' Golemansky, 1964 * ''

Arcella nordestina Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Vucetich, 1973 * ''

Arcella oblonga Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Schaudinn, 1898 * ''

Arcella oyei Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Stepanek, 1963 *'' Arcella peruviana'' Reczuga et al., 2015 *''

Arcella prismatica Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' Taylor, Strueder-Kypke and Siemensma * '' Arcella rotundata'' Playfair, 1918 * ''

Arcella rukiensis Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in Pond, ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which Pseudopodia, p ...

'' Van Oye, 1926 * ''

Arcella salobris Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in Pond, ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which Pseudopodia, p ...

'' Useros et al., 2023 * ''

Arcella spectabilis Arcella is a genus of testate amoebae in the order Arcellinida, commonly found in ponds, wetlands, moss, and soil. It is distinguished by a radially symmetrical organic shell, which features a central aperture through which pseudopods are exte ...

'' (Deflandre, 1928) Siemensma, 2025 *'' Arcella vulgaris'' Ehrenberg, 1830

References

External links

{{Authority control Amoebozoa genera Tubulinea Taxa named by Christian Gottfried Ehrenberg