A new species of testate amoeba, Arcella prismatica sp. nov. (Amoebozoa: Arcellinida), from peatlands in Ontario and Quebec, Canada

Résumé

Arcella is a genus of testate amoebae with a radially symmetrical shell composed of secreted material arranged in hexagonal units. Within the genus, species are distinguished by the morphology and dimensions of the shell. We describe a new species, Arcella prismatica sp. nov., discovered in a brown-water lake in the Mer Bleue Bog Conservation Area, a protected wetland in the city of Ottawa, Ontario, Canada. Specimens of the same morphotype have also been found in a subarctic peatland on the James Bay coast, near the village of Chisasibi, Quebec, Canada. The species has a polyhedral shell with a relatively flat dorsal surface and an irregularly crenulated aperture, a combination of characters not found in other members of the genus. The discovery of a novel and evidently widely distributed Arcella within the limits of a populous North American city is a reminder that the diversity of microbial eukaryotes is still poorly understood. Further exploration of undersampled peatland habitats can be expected to reveal new organisms and new relationships among known species.