Arcella artocrea Leidy, 1876
Basionym: Arcella artocrea Leidy, 1876
Synonym: Arcella artocrea aplanata Grospietsch, 1954

Diagnosis: Test height one-quarter to one-half of the diameter; dome convex; surface mammillated or pitted; test margin well defined, forming a raised border reaching approximately one-quarter to one-half of the test height. Shell circular in outline with a conical aboral region, often bearing depressions. The basal collar is usually prominent and smooth. Aperture invaginated, circular, with a small lip. Zoochlorellae are consistently present.

Dimensions: Literature: 152–216 µm.
Observed (this study): 160–202 µm.

Ecology: Bogs and Sphagnum ponds.

Remarks: This species was first described by Leidy (1876). Deflandre (1928) emended Leidy’s original description of Arcella artocrea and distinguished Arcella artocrea var. pseudocatinus, based on the presence or absence of pores and zoochlorellae, respectively.

References:
Leidy J. 1876. Remarks on Arcella, etc. Proceedings of the Academy of Natural Sciences of Philadelphia 3: 28.

González-Miguéns, R., Soler-Zamora, C., Villar-Depablo, M., Todorov, M., Lara, E., 2021. Multiple convergences in the evolutionary history of the testate amoeba family Arcellidae (Amoebozoa: Arcellinida: Sphaerothecina): when the ecology rules the morphology. Zoological Journal of the Linnean Society zlab074. https://doi.org/10.1093/zoolinnean/zlab074