Arcella prismatica Taylor, Strueder-Kypke & Siemensma (2025)

In 2014, I discovered this testate amoebae in a sample from Mer Bleue Bog, in Ottawa. Later, I found the same morphotype in the Cree Nation of Chisasibi, on the coast of James Bay. Recently, we described the species under the name Arcella prismatica. See: https://www.canadianfieldnaturalist.c… It has a flat dorsal surface, like that of Arcella costata, but the shell’s sides are roughly perpendicular to the ventral face, in profile view. Also, is has a frilly (crenulated) aperture, with eight or ten lobes. Polygonal, with five to eight sides. Test diameter 81-115 um, height 60-87 um. In mats of surface algae.