Pseudoblepharisma

Pseudoblepharisma is a genus of heterotrich ciliates inhabiting oxygen-depleted freshwater habitats. Most sources report that it contains one species, Pseudoblepharisma tenue, but at least four have been seen in literature.

The ciliate likely prefer an aerobic environment when in the dark, and because it is mixotrophic, it is hypothesized its anoxygenic photosynthesising bacterial endosymbionts allows it to enter anoxic environments where it will have access to the microbial prey living there.

European reports also mentioned a variant P. tenue var. viride, which only has green symbionts. In 2022, one strain matching these descriptions was found in tropical freshwaters of Florida, North America. Unlike the bicolor European counterpart, it builds a lorica (shell) around itself.

The current taxonomy (under Blepharismidae) is inconsistent with molecular phylogeny using SSU rRNA; the latter places the genus sister to Spirostomum (Spirostomidae).