Arcellinid
testate amoebae or Arcellinida,[1]Arcellacean[2] or lobose testate amoebae[3] are single-celled
protists partially enclosed in a simple
test (shell).
Arcellinid testate amoebae are commonly found in soils,
leaf litter, peat bogs and near/in fresh water.[1] They use their
pseudopodia, a temporary cell extension, for moving and taking in food. Like most amoebae, they are generally believed to
reproduce asexually via binary fission. However a recent review suggests that sexual recombination may be the rule rather than the exception in
amoeboid protists in general, including the Arcellinid testate amoebae.[4]
Test or shell
Simple tests are made by secretion (autogenous tests), agglutination of foreign material (xenogenous tests), or sometimes a combination of both. Past environmental changes can be determined by analysing the composition of fossil tests, including the reconstruction of past
climate change.[1] Testate amoebae species have been used to reconstruct hydrological changes over the late
Holocene, as a result of individual species possessing a narrow tolerance for ecohydrological conditions such as water-table depth or pH.[5]
Evolutionary history
Fossils of arcellinid testate amoebae date back to the
Tonian stage of the
Proterozoic, around 789-759 million years ago. The fossils indicate that by 730 million years ago, arcellinids had already diversified into major lineages.[6]
Testate amoebae are theorized to be mostly
polyphyletic (coming from more than one ancestral type), but testaceafilosea, one group of testate amoebae, are theorized to be
monophyletic. Ancient tests of terrestrial fauna are commonly found in fossilized amber,[7] although mid-Cretaceous testate amoeba (i.e., Diffligia, Cucurbitella) have been found in ancient lake sediments.[8] It is likely that the group has evolved minimally over the course of the
Phanerozoic.
^Woodland, Wendy, A. (1998). "Quantitative estimates of water tables and soil moisture in Holocene peatlands from testate amoebae". The Holocene. 8 (3): 261–273.
doi:
10.1191/095968398667004497.
S2CID128897334.{{
cite journal}}: CS1 maint: multiple names: authors list (
link)
^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,
ISBN1-891276-23-9, pp. 827-860
^Adl SM, Simpson AG, Lane CE, Lukeš J, Bass D, Bowser SS, Brown MW, Burki F, Dunthorn M, Hampl V, Heiss A, Hoppenrath M, Lara E, le Gall L, Lynn DH, McManus H, Mitchell EA, Mozley-Stanridge SE, Parfrey LW, Pawlowski J, Rueckert S, Shadwick L, Schoch CL, Smirnov A, Spiegel FW (2012).
"The Revised Classification of Eukaryotes". Journal of Eukaryotic Microbiology. 59 (5): 429–514.
doi:
10.1111/j.1550-7408.2012.00644.x.
PMC3483872.
PMID23020233.