Molecular phylogeny and taxonomy of four Remanella species (Protozoa, Ciliophora): A flagship genus of karyorelictean ciliates, with descriptions of two new species

During faunal studies of psammophilic ciliates along the coast of Qingdao, China, several marine karyorelictean species were isolated. Among them, four species within the genus Remanella were investigated, including two species new to science: i.e., R. rugosa, Remanella elongata sp. nov. , Remanella aposinica sp. nov. , and R. unicorpusculata. Remanella rugosa has been reported several times, but this study is the first to provide detailed morphological characters and phylogenetics. Remanella elongata sp. nov. can be distinguished from its congeners by the presence of complex cortical granules, fewer macronuclei, and longer body size. Remanella aposinica sp. nov. differs from its congeners by having 14–17 right lateral ciliary rows and 24–37 dikinetids of intrabuccal kinety. Poorly known Remanella rugosa var. unicorpusculata (Kahl, 1933) Foissner, 1996 should be elevated from subspecies to species level, Remanella unicorpusculata (Foissner, 1996) stat. nov. , based on detailed redescriptions with statistical data, living morphology, infraciliature, and species definitions. Small subunit (SSU) rDNA was sequenced for the four species, and phylogenetic analysis revealed that all known taxa in Remanella formed the outline branch to the genus Loxodes with moderate to high bootstrap support among Remanella lineages.