Order Arcellinida Kent 1880 Diagnosis: Cell covered with hard or highly rigid organic or mineral extracellular test consisting of either self-secreted elements (calcareous, siliceous or chitinoid), a sheet-like chitinoid structure, or recycled organic or mineral particles bound together, with a single main opening. Remarks: Arcellinida comprises all testate amoebae with lobose pseudopodia. It is the largest group of testate amoebae with 687 nominal species (Kosakyan et al, 2016). However, the major part of these species needs comprehensive nomenclature and taxonomic revision. Arcellinida exhibit a wide array of the test shapes composed of different material, which was the key characteristic for their classification. Meisterfeld (2000) organized them into three suborders: Arcellina, Difflugina and Phryganellina. Recent molecular investigations has challenged the system, and the positions of many species and genera were switched between families. These molecular reconstructions have demonstrated the limitations of the use of test composition as a classification character. A number of modifications were made on high as well as low-taxonomic levels. Higher-level taxonomy of Arcellinida is uncertain, while lower-level taxonomy is constantly changing (Kosakyan et al, 2016; Gomaa et al., 2017). Further reading: Kosakyan et al. (2016): Current and future perspectives on the systematics, taxonomy and nomenclature of testate amoebae – European Journal of Protistology Gomaa et al. (2017): A contribution to the phylogeny of agglutinating Arcellinida (Amoebozoa) based on SSU rRNA gene sequences – European Journal of Protistology 59: 99-107
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Sphaerothecina

Infraorder Sphaerothecina Kosakyan et al., 2016   Diagnosis: Testate amoebae with a more or less spherical or semi-spherical test and a central aperture; test build

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Microcorycia bryophila

after Decloitre, 1974 Microcorycia bryophila Decloitre, 1974 Diagnosis: “This species bears a slight remembrance to Microcorycia tessellata Penard. The differences are as follows: With tessellata,

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Pseudodifflugia procera

Pseudodifflugia procera, after Badewitz, 2003 Pseudodifflugia procera Badewitz, 2003 Diagnosis: Test elongated cylindrical, remarkably slim, with straight or slightly curved flanks, in cross-section circular. Living

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Christinellula spec.

“Christinellula” “Christinellula“ from Spiegelplas Diagnosis: This specimen was present in a sample from the Spiegelplas (‘Mirror Lake’) in the Netherlands. It differs from previous observed

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Thecamoeba sp. 3

Thecamoeba sp. n = nucleus Thecamoeba sp. Diagnosis: Surface in locomotion with some longitudinal dorsal folds; outline in locomotion broadly oblong; hyaloplasm usually in a

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Schoenbornia humicola

Schoenbornia humicola – after Schönborn et al., 1987 Schoenbornia humicola (Schönborn, 1964) Diagnosis: Test small, not compressed, hyaline, with Nebela-like irregular siliceous plates and sometimes

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