Tintinnine ciliates are widely distributed around the world and are characterized by the possession of a lorica that is highly diverse in structure and morphology. In the present study, five tintinnines, namely Tintinnopsis cf. radix, T. everta Kofoid and Campbell, 1929, T. mulctrella Kofoid and Campbell, 1929, Eutintinnus inflatus Marshall, 1969, and Favella ehrenbergii (Claparède and Lachmann, 1858) Jörgensen, 1924, were collected from coastal waters of Qingdao, China. Three are newly recorded from China, i.e., T. everta, T. mulctrella, and E. inflatus. The morphology of the lorica and cell proper of all five species are described and compared with original and subsequent descriptions. The morphology in vivo of the lorica and cell proper of all five species are described and compared with original and subsequent descriptions. In addition, the ciliary patterns of F. ehrenbergii and T. cf. radix are revealed based on protargol-stained specimens.

The ciliate genus Pleuronema comprises approximately 30 nominal species and has been reported in freshwater, brackish water, and marine habitats. Nevertheless, recent studies have indicated that there might be a large undiscovered species diversity. In the present work, four new Pleuronema species, namely P. foissneri sp. nov., P. parasmalli sp. nov., P. parasalmastra sp. nov., and P. paraorientale sp. nov., collected from Shenzhen, southern China, was investigated using taxonomic methods. The diagnosis, description, comparisons with morphologically related species and detailed morphometric data are supplied for each. The small subunit ribosomal RNA (SSU rRNA) gene of the four new species is sequenced and their molecular phylogeny is analyzed. The SSU rRNA gene tree shows that Pleuronema is polyphyletic comprising several separate clades. All four new species cluster consistently with P. orientale KF206429, P. puytoraci KF840520 and P. setigerum FJ848874 within the core Pleuronematidae + Peniculistomatidae clade. Phylogenies of Pleuronematidae-related taxa are also discussed.

The morphology, infraciliature and silverline system of two marine Euplotes, Euplotes sinicus sp. nov. and Euplotes parabalteatus sp. nov., isolated from seawater near Qingdao, China, were investigated. E. sinicus is characterized by having conspicuous dorsal ridges, a single marginal cirrus and a silverline system of the double-patella-I type. E. parabalteatus is an extremely small form (only about 35 μm long) with 6–7 dorsal kineties and a silverline system of the double-eurystomus type. Small subunit (SSU) rRNA-based phylogenetic trees were constructed with three different methods and these firmly demonstrated that the novel species represent two distinct phylogenetic lineages within the genus Euplotes, branching as a sister group to all other sequenced congeners. In addition, the SSU rRNA gene of another rare, morphologically similar form, Euplotes rariseta, was sequenced. This revealed the phylogenetic position of E. rariseta to be basal to one of the major groups of Euplotes rather than close to Euplotes nobilii.