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Prostomatean ciliates inhabit a wide range of aquatic environments and serve as a trophic link in food webs. However, the biodiversity and molecular phylogeny of the Prostomatea, especially the order Prostomatida, is poorly known owing to undersampling and the paucity of molecular data. Here, three prostomatid ciliates, Platina marina gen. nov. sp. nov. Parametacystis pulchra gen. nov. sp. nov. and Apsiktrata gracilis , were studied based on morphological data and small subunit ribosomal ribonucleic acid (SSU rRNA) gene sequences. The two new genera show a close relationship with the class Plagiopylea but a distant relationship with Metacystis , which bears a strong morphological similarity to the two new genera. The simplified oral ciliature can be regarded as a synapomorphy of the two new genera. The SSU rRNA gene of a representative of the family Apsiktratidae was sequenced for the first time. Morphological and phylogenetic analyses suggest that Apsiktratidae might be more closely related to Prorodontida than to Prostomatida, and the oral basket might be more phylogenetically informative than the brosse in distinguishing Prorodontida and Prostomatida. Supplementation with rare taxa reveals a close association between the Prostomatida and Trimyemidae. The putative secondary structure of the SSU rRNA V9 region suggests a sister relationship between the order Prostomatida and the class Plagiopylea. [ABSTRACT FROM AUTHOR]

Periphytic ciliates play a vital role in the material cycle and energy flow of microbial food web, however, their taxonomy and biodiversity are inadequately studied given their high species richness. Two new and one little known species, viz. Derouxella lembodes gen. et sp. nov., Cyrtophoron multivacuolatum sp. nov., and Cyrtophoron apsheronica Aliev, 1991, collected from coastal waters of China, were investigated using modern methods. Derouxella gen. nov. can be recognized by having dorsoventrally flattened body, a podite, one fragmented preoral kinety, two parallel circumoral kineties, and somatic kineties progressively shortened from right to left. Morphological classification and phylogenetic analyses based on nuclear small subunit ribosomal RNA (nSSU rRNA) and mitochondrial small subunit ribosomal RNA (mtSSU rRNA) gene sequence data inferred that Derouxella gen. nov. occupies an intermediate position between Hartmannulidae and Dysteriidae. Cyrtophoron multivacuolatum sp. nov. is characterized by large body size, the numbers of somatic kineties and nematodesmal rods, and having numerous contractile vacuoles. The genus Cyrtophoron and the poorly known species C. apsheronica were redefined. Even with the addition of newly obtained nSSU rRNA and mtSSU rRNA gene sequences of Cyrtophoron, the family Chlamydodontidae was still recovered as a monophyletic group, the monophyly of Cyrtophoron was supported too. [ABSTRACT FROM AUTHOR]

The diversity of the family Holophryidae is relatively poorly known due to a lack of studies using modern methods, the paucity of taxonomically informative characters for species circumscription, and the morphological similarity among holophryids. In the present study, two holophryid ciliates, namely Pelagothrix plancticola and Holophrya paradiscolor sp. nov., isolated from two freshwater ponds in Qingdao, China, are reported. The morphology of both species was described based on living observation and protargol staining, and their molecular phylogeny was analysed using SSU rRNA gene sequence data. Pelagothrix plancticola has never been redescribed since its establishment. Based on new data, an improved diagnosis of P. plancticola is supplied. Holophrya paradiscolor sp. nov. is distinguished by a combination of features including a single macronucleus, the absence of endosymbiotic green algae, and the presence of two types of extrusomes. Following the addition of two new sequences, the molecular phylogeny of the family Holophryidae was analysed. Finally, the information on the habitats and geographic distribution of holophryids was reviewed. [ABSTRACT FROM AUTHOR]

Prostomateans, as common inhabitants in diverse aquatic environments, are among the simplest ciliate lineages, and serve as trophic links in food webs. However, only a few members are well-known and thoroughly studied, and the diversity of this group remains elusive. The unique genus Plagiocampa has a long history of research, but few studies have been performed using up-to-date methods. In the present work, Plagiocampa longis Kahl, 1927 and Plagiocampa minima Kahl, 1927, collected from Chinese coastal habitats, were investigated based on microscopical observation, protargol staining, and SSU rRNA gene sequencing. Their ciliature and morphometric data as well as gene sequences are documented. Phylogenetic analyses revealed that the family Plagiocampidae is likely monophyletic and has a closer relationship with parasitic Cryptocaryon. [ABSTRACT FROM AUTHOR]

Prostomatean ciliates play important roles in the flow of material and energy in aquatic microbial food webs, and thus have attracted wide attention for over a century. Their taxonomy and systematics are, however, still poorly understood because of their relatively few taxonomically informative morphological characters. In this study, two new prostomateans, Lagynus binucleatus sp. n. and Foissnerophrys alveolata gen. n., sp. n., collected from a freshwater pool and the intertidal zone of a sandy beach, respectively, in Qingdao, China, are investigated using living observation, protargol staining, and SSU rRNA gene sequencing methods. The genus Lagynus is redefined, and the new species L. binucleatus sp. n. is established based on significant morphological differences with similar forms. Furthermore, a new genus, Foissnerophrys gen. n., is established based on a combination of morphological and molecular data with F. alveaolata sp. n. the type species by monotypy. The identities of intracellular prokaryotes of these two new species are discussed based on fluorescence in situ hybridization (FISH) data and newly obtained 16S rRNA gene sequences. [ABSTRACT FROM AUTHOR]

In the last two decades, cyrtophorian ciliates have been revealed to demonstrate a high species diversity. But this group remains difficult to study, mainly because of their low abundance and relatively few taxonomically informative morphological characters. As a contribution to the taxonomy of cyrtophorians, here we investigate three Dysteria species based on their live morphology, ciliary pattern, and molecular phylogeny. Dysteria ozakii nom. nov. can be recognized by its elongate body shape and four right kineties, including three frontoventral kineties. A neotype has to be fixed for the species as no type materials were deposited. The other two species, D. brasiliensis Faria et al., 1922 and D. compressa (Gourret & Roeser, 1886) Kahl, 1931, are redescribed and supplementary information for each is supplied. Phylogenetic analyses based on small-subunit (SSU) rRNA gene sequences support the validity of the species. In addition, four species of bacterial epibionts were observed on the surface of the three Dysteria spp. The identities of these bacterial species are discussed based on the newly obtained 16S rRNA gene sequences. [ABSTRACT FROM AUTHOR]