In this study, morphology of a Brazilian population of Eschaneustyla terricola Foissner, 1982 and a Chinese population of E. lugeri Foissner, Agatha & Berger, 2002 were studied based on living observation and protargol impregnation. Several stages of morphogenesis in E. lugeri were reported and the most remarkable features are characterized as follows: (1) partly renewal of adoral zone of membranelles in the proter and the parental midventral cirri do not join the construction of the opisthe’s oral primordium; (2) three or four buccal cirri each develop from one frontoventral cirral anlage and undulating membranes anlage generates two frontal cirri; (3) frontoventral cirral anlagen n and n-1 develop de novo and in the frontoterminal cirral row, respectively; (4) intrakinetal development of marginal and dorsal kineties anlagen; (5) fusion of macronuclear nodules into a single mass. 

 A Chinese population of Oxytricha nauplia Berger et Foissner, 1987 was recently discovered from the surface soil in the Kuisu Valley, Huhhot, China. Its morphology corresponds well with that of the original population in the body size and shape, the absence of cortical granules, two macronuclear nodules and two micronuclei. Both morphogenesis during binary fission and small subunit of ribosomal gene (SSU rDNA) of the species were first investigated. Though earlier dividers are unavailable for this species, morphogenesis almost proceeds as in congeners by given stages. The SSU rDNA sequence of O. nauplia is 1728 bp long and has a DNA G+C content of 45.72%. Phylogenetic analyses revealed that Oxytricha nauplia grouped with O. paragranulifera first with high support, and then clustered into a subclade including Onychodromopsis flexilis, Paroxytricha ottowi, Paroxytricha longigranulosa and Rigidothrix goiseri, which branched off most congeners, but clustered into the Oxytrichidae clade. 

We isolated an encysted ciliate from a geothermal field in Iceland. The morphological features of this isolate fit the descriptions of Dexiotricha colpidiopsis (Kahl, 1926) Jankowski, 1964 very well. These comprise body shape and size in vivo, the number of somatic kineties, and the positions of macronucleus and contractile vacuole. Using state-of-the-art taxonomic methods, the species is redescribed, including phylogenetic analyses of the small subunit ribosomal RNA (SSU rRNA) gene as molecular marker. In the phylogenetic analyses, D. colpidiopsis clusters with the three available SSU rRNA gene sequences of congeners, suggesting a monophyly of the genus Dexiotricha. Its closest relative in phylogenetic analyses is D. elliptica, which also shows a high morphological similarity. This is the first record of a Dexiotricha species from a hot spring, indicating a wide temperature tolerance of this species at least in the encysted state. The new findings on D. colpidiopsis are included in a briefly revision of the scuticociliate genus Dexiotricha and an identification key to the species. 

The morphology and morphogenesis of two populations of the soil hypotrichous ciliate, Parakahliella macrostoma (Foissner, 1982) Berger et al. 1985, isolated from northwest China, were investigated based on specimens examined in vivo and stained with protargol. Our populations resemble the original one in terms of their live characters and cirral pattern. The main events during binary fission are as follows: (1) the parental adoral zone of membranelles is retained completely by the proter; (2) both in the proter and in the opisthe five frontal-ventral cirral anlagen are recognizable; (3) the marginal rows and dorsal kineties develop intrakinetally. In addition, the SSU rRNA gene was sequenced for the genus Parakahliella for the first time. Molecular phylogenetic analyses suggest that two populations of the genus Parakahliella cluster together and have a close relationship with species of Oxytrichidae. 

Trichodina rectuncinata is one of the trichodinids most widely distributed in marine fish. This ciliate species has been recorded in more than 20 host species belonging to 17 fish families worldwide. Previous comparative studies based on morphometric data revealed considerable morphological variation among specimens from different populations of T. rectuncinata. In this study, we conducted a morphometric-molecular analysis of three populations of T. rectuncinata to evaluate potential differences among 18S rRNA sequences, in relation to morphological variations. Smears were obtained from marine fishes in three localities along the Pacific coast of Mexico. Based on the shape of denticles, we found four different morphotypes for T. rectuncinata. This morphological variability does not correspond with the genetic divergence, suggesting that all analyzed populations belong to the same species. Further analyses using more variable markers are necessary to corroborate the findings of our study.