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Arcella

{{Short description|Genus of protozoa}}

{{Other uses}}

{{Taxobox

| image = Arcella spectabilis.jpg

| image_caption = Arcella spectabilis from Mer Bleue, Ottawa

| domain = Eukaryota

| phylum = Amoebozoa

| classis = Tubulinea

| ordo = Arcellinida

| familia = Arcellidae

| genus = Arcella

| genus_authority = Ehrenberg, 1830

}}

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 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 across diverse environments.{{Cite journal |last=González-Miguéns |first=Rubén |last2=Soler-Zamora |first2=Carmen |last3=Villar-Depablo |first3=Mar |last4=Todorov |first4=Milcho |last5=Lara |first5=Enrique |date=2022-04-01 |title=Multiple convergences in the evolutionary history of the testate amoeba family Arcellidae (Amoebozoa: Arcellinida: Sphaerothecina): when the ecology rules the morphology |url=https://academic.oup.com/zoolinnean/article/194/4/1044/6410131 |journal=Zoological Journal of the Linnean Society |volume=194 |issue=4 |pages=1044–1071 |doi=10.1093/zoolinnean/zlab074 |issn=0024-4082}}

File:Arcella conica.jpg

History and classification

File:Arcella vulgaris Ehrenberg 1830.jpg

The genus Arcella was established in 1830 by the German zoologist C. G. Ehrenberg, who designated Arcella vulgaris as the type species.{{Cite book |last=Deutsche Akademie der Wissenschaften zu Berlin. |url=https://www.biodiversitylibrary.org/item/93803#page/9/mode/1up |title=Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin |last2=Berlin |first2=Deutsche Akademie der Wissenschaften zu |date=1830 |publisher=Realschul-Buchhandlung |volume=1830 |location=Berlin}} 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.{{Cite journal |last=Taylor |first=Bruce |last2=Strüder-Kypke |first2=Michaela |last3=Siemensma |first3=Ferry |date=2025-01-17 |title=A new species of testate amoeba, Arcella prismatica sp. nov. (Amoebozoa: Arcellinida), from peatlands in Ontario and Quebec, Canada |url=https://www.canadianfieldnaturalist.ca/index.php/cfn/article/view/3195 |journal=The Canadian Field-Naturalist |volume=138 |issue=1 |pages=1–15 |doi=10.22621/cfn.v138i1.3195 |issn=0008-3550|url-access=subscription }}

In 2021, González-Miguéns et al. conducted a comprehensive revision of the family Arcellidae, using molecular phylogenetics 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. 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.{{Cite web |title=Galeripora – Microworld |url=https://arcella.nl/galeripora/ |access-date=2025-05-06 |language=en-US}}

Anatomy

Species of Arcella are typically enclosed in a domed or umbrella-shaped test (shell) with a single central aperture.[http://www.nies.go.jp/chiiki1/protoz/morpho/testacea/arcella.htm "Arcella Ehrenberg, 1832"]. National Institute for Environmental Studies, Japan. 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 and manganese compounds.Ralf Meisterfeld and Edward Mitchell (2008). [http://tolweb.org/Arcella/124482 "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.{{Cite web |title=Arcella – Microworld |url=https://arcella.nl/arcella/ |access-date=2025-05-06 |language=en-US}}

Nutrition and distribution

Arcella inhabit a wide range of freshwater environments, including pools, eutrophic waters, marshes, mosses, 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.{{Cite journal |last=Useros |first=Fernando |last2=González-Miguéns |first2=Rubén |last3=Soler-Zamora |first3=Carmen |last4=Lara |first4=Enrique |date=2023-08-01 |title=When ecological transitions are not so infrequent: independent colonizations of athalassohaline water bodies by Arcellidae (Arcellinida; Amoebozoa), with descriptions of four new species |url=https://academic.oup.com/femsec/article/99/8/fiad076/7220537 |journal=FEMS Microbiology Ecology |volume=99 |issue=8 |pages=fiad076 |doi=10.1093/femsec/fiad076 |issn=0168-6496|pmc=10389689 }}

Like other amoebae, Arcella use their pseudopods to take in food. They feed on bacteria, green algae, diatoms, fungi, flagellates and small ciliates.{{Cite journal |last=Laybourn |first=Gohanna |last2=Whymant |first2=Lindsay |date=1980-05-01 |title=The effect of diet and temperature on reproductive rate in Arcella vulgaris Ehrenberg (Sarcodina: Testacida) |url=https://link.springer.com/article/10.1007/BF00346471 |journal=Oecologia |language=en |volume=45 |issue=2 |pages=282–284 |doi=10.1007/BF00346471 |issn=1432-1939|url-access=subscription }}

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.{{Cite journal |last=Reczuga |first=Monika K. |last2=Swindles |first2=Graeme T. |last3=Grewling |first3=Łukasz |last4=Lamentowicz |first4=Mariusz |date=2015-10-01 |title=Arcella peruviana sp. nov. (Amoebozoa: Arcellinida, Arcellidae), a new species from a tropical peatland in Amazonia |url=https://www.sciencedirect.com/science/article/abs/pii/S0932473915000036?casa_token=m2fX7DMPargAAAAA:sPMgtnBbv38biQFqRSr_HQ47IELaWe2NuVHi6RSx7a9VXFjLzTQtrmFdrXjg3CuuKMgT-eB3TA |journal=European Journal of Protistology |volume=51 |issue=5 |pages=437–449 |doi=10.1016/j.ejop.2015.01.002 |issn=0932-4739|url-access=subscription }}{{Cite journal |last=Feres |first=J. C. |last2=Porfirio-Sousa |first2=A. L. |last3=Ribeiro |first3=G. M. |last4=Rocha |first4=G. M. |last5=Sterza |first5=J. M. |last6=Souza |first6=M. B. G. |last7=Soares |first7=C. E. A. |last8=Lahr |first8=D. J. G. |date=2016 |title=Morphological and morphometric description of a novel shelled amoeba Arcella gandalfi sp. nov. (Amoebozoa: Arcellinida) from Brazilian continental waters |url=https://agro.icm.edu.pl/agro/element/bwmeta1.element.agro-92cc8ad1-85f8-46f9-8e1e-4ecedbb7575d |journal=Acta Protozoologica |language=EN |volume=55 |issue=4 |doi=10.4467/16890027AP.16.021.6008 |issn=0065-1583}}

Species

References

{{Reflist}}

External links

{{Wikispecies}}

{{Commons category|Arcella}}

{{Amoebozoa}}

{{Taxonbar|from=Q971534}}

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Category:Amoebozoa genera

Category:Tubulinea

Category:Taxa named by Christian Gottfried Ehrenberg