Cyphoderia compressa has only been described from supralittoral environments, as a psammobiont, with salinities from 1.33 to 36.00 ‰. Other Cyphoderia such as those in the C. ampulla species complex are more ecologically and environmentally widespread, occurring as free-living individuals within water bodies or in association with vegetation, and over a wider salinity range, including freshwater. We postulate that C. compressa may not be as restricted in terms of its environmental or ecological distribution. To this end, we examined a variety of water and sediment samples from Scottish localities, ranging from supralittoral to inland freshwater environments. The Scottish material occurs as a psammobiont within supralittoral beach sands and is newly recorded within sands from freshwater to brackish stream sections and along the margin of the freshwater Loch Lomond. It is also recorded from freshwater to brackish settings as part of the stream and pond water biota, associated biofilm and vegetative material. Test morphology is more variable than previously appreciated, including those with a papillate fundus, and many that are not as laterally compressed as typified by the species. Differences in plate morphology and size were also noted, as well as a novel arcuate cross-cutting ridged cement structure, that is restricted to C. compressa.

Euplotes baugilensis n. sp. was discovered in a temporary puddle that formed after rainfall on a mountain footpath near Gangneung-Wonju National University in Gangneung, South Korea. After isolation, a pure culture was established, and the cells were examined using live observation, silver-impregnation (protargol and ‘wet’ silver nitrate), scanning electron microscopy, and the analysis of the 18S rRNA gene sequence. Morphologically, E. baugilensis n. sp. is characterized by small body size (on average 49 × 31 µm in vivo), 9 ordinary fronto-ventral cirri (cirrotype-9) with one reduced cirrus V/2 (composed of four non-ciliated basal bodies), 5 transverse cirri, 7 or 8 dorsolateral kineties, 6 dorsal prominent ridges, and a dargyrome (silverline system) of double type. In this study, we have used a combination of morphological and molecular techniques to characterize E. baugilensis n. sp., and determine its phylogenetic position within the genus Euplotes. Molecular analysis using 18S rRNA gene sequences indicated that E. baugilensis n. sp. is most closely related to E. curdsi (with a sequence identity of 96.8 %).

Cyphoderia compressa has only been described from supralittoral environments, as a psammobiont, with salinities from 1.33 to 36.00 ‰. Other Cyphoderia such as those in the C. ampulla species complex are more ecologically and environmentally widespread, occurring as free-living individuals within water bodies or in association with vegetation, and over a wider salinity range, including freshwater. We postulate that C. compressa may not be as restricted in terms of its environmental or ecological distribution. To this end, we examined a variety of water and sediment samples from Scottish localities, ranging from supralittoral to inland freshwater environments. The Scottish material occurs as a psammobiont within supralittoral beach sands and is newly recorded within sands from freshwater to brackish stream sections and along the margin of the freshwater Loch Lomond. It is also recorded from freshwater to brackish settings as part of the stream and pond water biota, associated biofilm and vegetative material. Test morphology is more variable than previously appreciated, including those with a papillate fundus, and many that are not as laterally compressed as typified by the species. Differences in plate morphology and size were also noted, as well as a novel arcuate cross-cutting ridged cement structure, that is restricted to C. compressa.

Coleps is a common genus of pelagic ciliates in freshwater and brackish water habitats. Classification and phylogeny of Coleps species are, however, still full of confusion. In this study, we investigated Coleps shanghaiensis n. sp., collected from a river in Shanghai, China, by living observation, protargol staining, and molecular methods. Coleps shanghaiensis is about 70–90 µm × 35–55 µm in size, has a barrel-shaped body with three posterior spines, and possesses 21–24 ciliary rows, each composed of two perioral dikinetids and 19–22 monokinetids, and six caudal cilia. In SSU rRNA gene phylogenies, C. shanghaiensis fell within the clade of subspecies of Levicoleps biwae, which questions the validity of the genus Levicoleps. Furthermore, the biogeography of the genus Coleps is discussed.

Despite their high abundance and wide distribution in ecosystems, most protists remain unknown to the public. Although science communication approaches were developed in historical times to raise public awareness of these ‘enigmatic’ taxa, many aspects have not been considered in the spotlight of modern techniques. We present selected ideas and activities on how to attract the public to unicellular eukaryotes. We give examples of how protists can be included in educational work. We explain that trained non-experts can understand and teach others how to recognize protists, where they live, in which habitats they can be found, what they look like and why they are important. Consequently, members of the public can learn how environmental threats impact not only the lives of protists but also ours, e.g., by the accumulation of microplastics through an aquatic food web, up to fish used for human consumption. We suggest age-appropriate methods for application in workshops on protist recognition.

The subclass Trichostomatia (Ciliophora, Litostomatea) constitutes a well-supported monophyletic group, which includes ciliates exclusively found as symbionts of vertebrates, primarily herbivorous mammals. Recent molecular analyses reinforce the subclass monophyly, though almost all orders, suborders, families, and genera are found to be non-monophyletic. Here, we reconstructed the evolutionary history of the subclass Trichostomatia using a phylogenomic approach and discussed some systematic inconsistencies. We propose a new Ophryoscolecidae genus, Dagostonium, to include Diplodinium polygonale. Monoposthium cynodontum is transferred to the genus Cycloposthium.

Acanthamoeba castellanii (Douglas, 1930) Page, 1967 is the type species of a widespread genus of free-living amoebae, potentially pathogenic for humans and animals. The Neff strain is one of the most widely used in biological research, serving as a model for both A. castellanii and the whole genus in general. The Neff strain, isolated in California, closely resembles another strain found in France and originally described as a separate species, Acanthamoeba terricola Pussard, 1964, but both were successively synonymized with A. castellanii. Molecular sequence analysis has largely replaced morphological diagnosis for species identification in Acanthamoeba, and rDNA phylogenies show that the Neff strain forms a distinct lineage from that of the type strain of A. castellanii. In this study, we compared the type strain of A. terricola with the Neff strain and A. castellanii, and analysed the available molecular data including new sequences obtained from A. terricola. Here we provide molecular evidence to validate the species A. terricola. The Neff strain is therefore transferred to A. terricola and should no longer be considered as belonging to A. castellanii.

Predatory protists play a central role in nutrient cycling and are involved in other ecosystem functions by predating the microbiome. While most soil predatory protist species arguably are bacterivorous, some protist species can prey on eukaryotes. However, studies about soil protist feeding mainly focused on bacteria as prey and rarely tested both bacteria and eukaryotes as potential prey. In this study, we aimed to decipher soil predator–prey interactions of three amoebozoan and three heterolobosean soil protists and potential bacterial (Escherichia coli; 0.5–1.5 µm), fungal (Saccharomyces cerevisiae; 5–7 µm) and protist (Plasmodiophora brassicae; 3–5 µm) prey, either as individual prey or in all their combinations. We related protist performance (relative abundance) and prey consumption (qPCR) to the protist phylogenetic group and volume. We showed that for the six soil protist predators, the most suitable prey was E. coli, but some species also grew on P. brassicae or S. cerevisiae. While protist relative abundances and growth rates depended on prey type in a protist species-specific manner, phylogenetic groups and volume affected prey consumption. Yet we conclude that protist feeding patterns are mainly species-specific and that some known bacterivores might be more generalist than expected, even preying on eukaryotic plant pathogens such as P. brassicae.

Chicken coccidiosis causes disastrous losses to the poultry industry all over the world. Eimeria tenella is the most prevalent of these disease-causing species. Our former RNA-seq indicated that E. tenella ankyrin repeat-containing protein (EtANK) was expressed differently between drug-sensitive (DS) and drug-resistant strains. In this study, we cloned EtANK and analyzed its translational and transcriptional levels using quantitative real-time PCR (qPCR) and western blotting. The data showed that EtANK was significantly upregulated in diclazuril-resistant (DZR) strain and maduramicin-resistant (MRR) strain compared with the drug-sensitive (DS) strain. In addition, the transcription levels in the DZR strains isolated from the field were higher than in the DS strain. The translation levels of EtANK were higher in unsporulated oocysts (UO) than in sporozoites (SZ), sporulated oocysts (SO), or second-generation merozoites (SM), and the protein levels in SM were significantly higher than in UO, SO, and SZ. The results of the indirect immunofluorescence localization showed that the protein was distributed mainly at the anterior region of SZ and on the surface and in the cytoplasm of SM. The fluorescence intensity increased further with its development in vitro. An anti-rEtANK polyclonal antibody inhibited the invasive ability of E. tenella in DF-1 cells. These results showed that EtANK may be related to host cell invasion, required for the parasite’s growth in the host, and may be involved in the development of E. tenella resistance to some drugs.

Ciliates of the class Plagiopylea play a vital role in various anaerobic environments as consumers of prokaryotes. Yet, the diversity and phylogeny of this group of ciliates, especially marine representatives, remain poorly known. In this study, three Parasonderia species, viz., Parasonderia elongata spec. nov., and the already known P. cyclostoma and P. vestita, discovered in anaerobic sediments from various intertidal zones in China, were investigated based on their living morphology, infraciliature, and small subunit ribosomal rRNA gene sequences. Parasonderia elongata can be recognized by its larger body size, elongated body shape, oval oral opening, number of oral kineties, and significantly shortened leftmost postbuccal polykineties on the cell surface. Improved diagnosis and redescription of P. cyclostoma is provided for the first time, including data on infraciliature and molecular sequence. Phylogenetic analyses revealed that the three species cluster together and with the sequence of a Chinese population of P. vestita already present in the GenBank database, forming a robust clade.