A Case Building Ciliate in the Genus Pseudoblepharisma Found in Subtropical Fresh Water

Abstract

The genus Pseudoblepharisma is currently comprised of only one species, P. tenue, and one variant, P. tenue var. viride, both described as free-living ciliates thriving in oxygen depleted freshwater habitats of Europe. Here we report on this genus being discovered from subtropical freshwaters of Florida, USA. The Florida strain diverges from the P. tenue by being much larger, as well as having a far higher density of intracellular symbiotic green algae, resembling P. tenue var. viride. Unlike its European counterparts, the North American strain was observed to build a lorica, likely useful for protection and feeding; this has not been previously described for this genus. In contrast to P. tenue, the Florida strain does not have endosymbiotic purple bacteria. Despite large distances between sampling zones, the species is a close match at a morphological level to Pseudoblepharisma tenue var. viride. We provide the first 18S rRNA gene sequence for this species, allowing future investigations into the biogeography of this genus. As intensive sampling efforts continue to increase, cryptic microbial species will continue to be recorded from diverse freshwater habitats at a global scale.