We isolated an encysted ciliate from a geothermal field in Iceland. The morphological features of this isolate fit the descriptions of 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, clusters with the three available SSU rRNA gene sequences of congeners, suggesting a monophyly of the genus . Its closest relative in phylogenetic analyses is , which also shows a high morphological similarity. This is the first record of a species from a hot spring, indicating a wide temperature tolerance of this species at least in the encysted state. The new findings on are included in a briefly revision of the scuticociliate genus and an identification key to the species.

The first transmission and scanning electron microscopical studies in combination with freeze-fracture technology have disclosed some important morphological and ultrastructural features in the freshwater oligotrichid . (I) The dikinetids (paired basal bodies) of the girdle kinety have a club-shaped cilium associated only with each left basal body. The electron-dense (paraflagellar) body on one side of its "9×2+2"-axoneme and the regular array of intramembranous particles indicate a sensory, perhaps photoreceptor function of these club-shaped cilia. (II) The stichomonad endoral membrane is proximally covered by a cytoplasmic fold and distally by multiple membranous layers. Thus entirely covered, the endoral is probably no longer involved in food capture; nonetheless, its associated microtubules might stabilise the cytopharynx. (III) Instead of a contractile vacuole, a horizontal ring-canal with supposed osmoregulatory function occurs. (IV) The extrusive nature of the trichites is not only observed in electron micrographs, but the attachment sites of these organelles also display a rosette of "8+1"-particles in the P-face of freeze-fracture replicas typical for ciliate extrusomes. (V) The neoformation organelle, the subsurface tube in which stomatogenesis takes place, shows short basal bodies and normal axonemes about 1 μm long. It is accompanied by numerous membrane vesicles, which might provide membrane material for the outgrowing cilia.

Molecular phylogenies of Oligotrichea currently do not contain all genera and families and display topologies which are often incongruent with morphological findings. In ciliates, the somatic kinetids are rather conserved, i.e., their ultrastructures, particularly the fibrillar associates, often characterise the main groups, except for the choreotrichids. Four different kinetid types are found in protargol-stained choreotrichids and used for reconstructing the taxon's evolution (the "Kinetid Transformation Hypothesis"). Proof for this hypothesis requires transmission electron microscopic studies, which are very rare in the choreotrichids and oligotrichids. Such an approach provides insights into the ultrastructural variability of somatic kinetids in spirotrichs and may also detect apomorphies characterising certain choreotrichid families. In the model tintinnid , the ultrastructure of the three kinetid types in the somatic ciliature is studied in cryofixed cells. The data support the "Kinetid Transformation Hypothesis" regarding tintinnids with a ventral kinety. This first detailed study on kinetids in tintinnids and choreotrichids in general reveals totally new kinetid types in ciliates: beyond the three common associates, they are characterised by two or three conspicuous microtubular ribbons extending on the kinetids' left sides. These extraordinary ribbons form together with the overlapping postciliary ribbons a unique network in the cortex of the anterior cell portion. The evolutionary constrains which might have fostered the development of such structures are discussed for the Oligotrichea, the choreotrichids, and tintinnids as their first occurrence is currently uncertain. Additionally, the kinetids in tintinnids, aloricate choreotrichids, oligotrichids, hypotrichs, and euplotids are compared.

Tintinnids (Ciliophora: Spirotricha: Tintinnina) are occasionally the dominant ciliates in the marine plankton. The tintinnid loricae are minute artworks fascinating scientists for more than 230 years, but their chemical composition remained unclear, viz., chitinous or proteinaceous substances were discussed. Since sedimenting loricae contribute to the flux of elements and organic compounds in the oceans, knowledge about their nature is necessary in assessing their ecological role. Previous techniques and new methods, e.g. enzymatic digestion and high-resolution transmission electron microscopy, are applied in the present study. A chitinous nature of the loricae is rejected by the Van-Wisselingh test and failure of chitinase digestion. Only proteins might show a resistance against strong hot bases (KOH at 160°C for ~ 40 min. in tintinnid loricae) similar to that of chitin. Actually, the presence of nitrogen in the EDX analyses and the digestion of at least some loricae by proteinase K strongly indicate a proteinaceous nature. Furthermore, the crystal lattice revealed by high-resolution TEM in Eutintinnus loricae is similar to the proteinaceous surface layer (S-layer) of archaea, and the striation recognizable in transverse sections of Eutintinnus loricae has a periodicity resembling that of the crystalline proteins in the extruded trichocysts of Paramecium and Frontonia. The proteolytic resistance of some loricae does not reject the idea of a proteinaceous nature, as proteins in S-layers of some archaea and in most naturally occurring prions show comparable reactions. The data from the present study and the literature indicate proteins in the loricae of thirteen genera. Differences in the proteolytic resistance and staining properties between genera and congeners are probably due to deviations in the protein composition and the additional substances, e.g. lipids, carbohydrates. At the present state of knowledge, correlations between lorica structure, wall texture, ultrastructure of the lorica forming granules, and the histochemical and enzymatic findings are not evident. Therefore, further studies are required to estimate the taxonomic significance of these features and the ecological role of sedimenting loricae.

Bromeliothrix metopoides was discovered in tank bromeliads from Central and South America. Pure cultures could be established in various media stimulating growth of its food, i.e. bacteria and heterotrophic flagellates of the genus Polytomella. The new ciliate was investigated in the light- and scanning electron microscope, with various silver impregnation techniques, and with molecular methods, using the small-subunit rDNA. The morphology and its changes during the life cycle are documented by 167 figures and a detailed morphometry. Bromeliothrix metopoides is about 27-55 × 22-36 μm in size and has a complex life cycle with Metopus-shaped, bacteriophagous theronts and trophonts (microstomes) and obovate, flagellate-feeding macrostomes having a large, triangular oral apparatus. The thin-walled resting cysts of the theronts and trophonts are uniquely ellipsoidal, while the thick-walled cyst of the macrostome morph is globular. Reproduction occurs in freely motile condition either by binary fission or polytomy, producing a unique, motile "division chain" composed of four globular offspring, of which the central ones are connected by a curious, plug-like holdfast. Division is associated with a complete reorganization of the parental oral and somatic infraciliature. Stomatogenesis is merotelokinetal as in other members of the order Colpodida. The right polykinetid is generated by the rightmost postoral kinety, while the left polykinetid is produced by the two left postoral kineties and five left side kineties. The division in freely motile condition resembles the Exocolpodidae Foissner et al., 2002, to which Bromeliothrix is tentatively assigned, differing from Exocolpoda mainly by the formation of a macrostome morph and a division chain. Bromeliothrix has a ciliary and silverline pattern typical for members of the family Colpodidae. This matches the molecular classification which, however, hardly reflects the outstanding division and life cycle, suggesting some decoupling of morphological and molecular evolution. The specific morphological and ontogenetic traits of Bromeliothrix are interpreted as adaptations to the highly competitive habitat, favouring r-selected life strategies. Bromeliothrix metopoides is widespread in various tank bromeliads and can be easily cultivated in a wide variety of limnetic and terrestrial media. Thus, it remains obscure why this ciliate is restricted to tank bromeliads, i.e. did not occur in about 2,000 soil and freshwater samples investigated globally, including some 100 samples from Central and South America.

Tintinnopsis parvulaJörgensen, 1912 has apparently a cosmopolitan distribution in the pelagial of marine and brackish coastal waters. The species is redescribed based on material from the Irish Sea off the Isle of Man, using live observation, protargol impregnation, and scanning electron microscopy. The agglomerated and stiff lorica measures 38-60 × 24-31 μm and is composed of a usually broadly obovate bowl and a slightly narrowed cylindroidal collar with an inner diameter of ~ 20 μm. The somatic ciliary pattern is of the most complex type, viz., it comprises a ventral, dorsal, and posterior kinety as well as a right, left, and lateral ciliary field. The left ciliary field comprises four kineties, the lateral field about ten kineties, and the right field five kineties. The oral primordium develops apparently apokinetally posterior to the lateral ciliary field and generates ~ 15 collar membranelles and one buccal membranelle. Two further populations were studied: one from the North Sea off the Island of Sylt, the other from brackish polder basins at the German North Sea coast; they match the Irish Sea specimens in all main features. The loricae formed in almost particle-free cultures have a thin wall composed of an irregular network of fibres and very few attached or interwoven particles. This matrix type differs from the other three types found in congeners. Hence, the matrix ultrastructure might represent a promising feature for a reliable subdivision of the species-rich genus TintinnopsisStein, 1867 in the future.

Using standard methods, we studied the morphology and 18S rDNA sequence of some peritrich ciliates from tank bromeliads of Costa Rica, Jamaica, and Ecuador. The new genus Orborhabdostyla differs from Rhabdostyla by the discoidal macronucleus. Two species from the literature and a new species from Ecuadoran tank bromeliads are combined with the new genus: O. previpes (Claparède and Lachmann, 1857) nov. comb., O. kahli (Nenninger, 1948) nov. comb., and O. bromelicola nov. spec. Orborhabdostyla bromelicola is a slender species with stalk-like narrowed posterior half and operculariid/epistylidid oral apparatus. An epistylidid relationship is also suggested by the gene sequence. Vorticella gracilis, described by Dujardin (1841) from French freshwater, belongs to the V. convallaria complex but differs by the yellowish colour and the number of silverlines. The classification as a distinct species is supported by the 18S rDNA, which differs nearly 10% from that of V. convallaria s. str. Based on the new data, especially the very stable yellowish colour, we neotypify V. gracilis with the Austrian population studied by Foissner (1979). Vorticella gracilis forms a strongly supported phyloclade together with V. campanula, V. fusca and V. convallaria, while Vorticellides astyliformis and Vorticella microstoma branch in a separate, fully-supported clade that includes Astylozoon and Opisthonecta. The new genus Vorticellides comprises five small (usually < 60 μm), barrel-shaped species with two epistomial membranes: V. aquadulcis (Stokes, 1887) nov. comb., V. astyliformis (Foissner, 1981) nov. comb., V. platysoma (Stokes, 1887) nov. comb., V. infusionum (Dujardin, 1841) nov. comb., and V. (Spinivorticellides) echini (King, 1931) nov. comb. Two of these species are redescribed in the present study: V. astyliformis and V. aquadulcis, which is neotypified with a Costa Rican population. Pseudovorticella bromelicola nov. spec. differs from the congeners by the location of the two contractile vacuoles and the number of silverlines.

Maryna umbrellata (Gelei, 1950) Foissner, 1993 is a colpodid ciliate common in ephemeral water bodies. Pure cultures were established and the resting cyst studied by light and electron microscopy, protease digestion of thin sections, and various cytochemical reactions shown by colour micrographs. The cyst of M. umbrellata belongs to the kinetosome-resorbing (KR) type and has a conspicuous glass cover described by Foissner et al. (2009). It is 100 μm across and the about 13 μm thick wall, which amounts for half of the total cyst volume, consists of four distinct layers: (i) the about 6 μm thick pericyst, which is composed of glass granules embedded in mucoproteins, and of a basal layer consisting of glycogen tubules about 20 nm across; (ii) the about 140 nm thick, electron-dense ectocyst, which is not digested by protease; (iii) the about 6 μm thick mesocyst, which is distinctly laminated and made of proteins; and (iv) the thin, about 500 nm thick endocyst, which is structureless and consists of glycoproteins. The meso- and endocyst are highly elastic, reducing their diameter by 50% when the encysted ciliate is removed. The cyst contents is dominated by up to 7 μm-sized "spongy globules" consisting of an electron-dense, proteinaceous matrix burrowed by electron-lucent strands of glycogen, providing the cyst with a curious, white-spotted appearance in the electron microscope. The small lipid droplets have a proteinaceous centre. The cyst plasm contains proteins and unstructured mucosubstances, which stain with alcian blue, and thus possibly originate from the decomposed mucocysts. This study suggests that ciliate resting cysts are much more diverse than indicated by literature data.

The genera Coriplites Foissner, 1988 and Apocoriplites nov. gen., which differ by the number of dorsal brush rows (3 vs. 2), belong to the haptorid Litostomatea and have a distinct feature in common: they lack oral extrusomes. Based on three new species, the diagnosis of the genus Coriplites is amended to include the wide spacing of the brush dikinetids and the heavily refractive cortical granules. Using standard methods, we redescribe C. terricola Foissner, 1988 and describe three new species: C. grandis (from swamp soil of Australia), C. proctori (from tanks of bromeliads in Jamaica), and Apocoriplites lajacola (from granitic rook-pools in Venezuela). Species are distinguished by the nuclear apparatus (a single nodule vs. two nodules with a micronucleus in between), the body size (<100 μm vs. >100 μm), the number of ciliary rows, and details of the dorsal brush (isostichad vs. heterostichad). In over 1,000 soil samples, only C. terricola has been found in all main biogeographic regions, while the other species have been found only at their type locality, i.e., in the southern hemisphere, where the genus possibly originated.

Neokeronopsis (Afrokeronopsis) aurea nov. subgen., nov. spec. was discovered in soil from the floodplain of a small river in the Krueger National Park, Republic of South Africa. Its morphology, ontogenesis, and 18S rDNA were studied with standard methods. Furthermore, we supplemented the data on N. (N.) spectabilis by reinvestigating the preparations deposited in the British Museum of Natural History. Neokeronopsis (Afrokeronopsis) aurea is a very conspicuous ciliate because it has an average size of 330 × 120 μm and is golden yellow due to the orange-coloured cytoplasm and citrine cortical granules. Further main characteristics include the semirigid body; the urostylid cirral pattern with a distinct corona of frontal and pseudobuccal cirri both originating from the midventral rows; multiple anterior fragmentation of dorsal kineties 1-3; multiple posterior fragmentation of kinety 3, commencing with an unique whirl of kinetofragments; three caudal cirri; an oxytrichid/cyrtohymenid oral apparatus with polystichad paroral membrane and buccal depression; a single oral primordium developing along the transverse cirral row; and an oxytrichid 18S rDNA. These peculiarities are used to establish the new oxytrichid family Neokeronopsidae, the new subgenus Afrokeronopsis, and the new species N. (A.) aurea. Further, these features confirm the CEUU hypothesis, i.e., convergent evolution of a midventral cirral pattern in urostylid and oxytrichid hypotrichs; additionally, N. (A.) aurea is the first (semi)rigid hypotrich with cortical granules and the second one with midventral rows, breaking the granule and flexibility dogmas. These and other observations show that the phylogeny of the hypotrichs is full of convergences. Thus, only a combined effort of classical and molecular phylogeneticists will provide the data needed for a natural classification. Based on the CEUU hypothesis, the molecular data, and literature evidence, we suggest that midventral oxytrichids should be ranked as distinct families; accordingly, we establish a further new family, the Uroleptidae, which forms a distinct clade within the oxytrichid molecular trees. Neokeronopsis is possibly related to Pattersoniella because it has the same special mode of forming the buccal cirri and possesses a buccal depression found also in Steinia, a close relative of Pattersoniella. The large size and conspicuous colour make N. (A.) aurea a biogeographic flagship possibly confined to Africa or Gondwana, while Neokeronopsis (N.) spectabilis (Kahl, 1932) is an Eurasian flagship.

During the 6 min-lasting "free-fall conditions" (4 x 10(-6) g) of the parabolic flight of a sounding rocket Paramecium aurelia cells showed an increase of 7.5 % in their mean swimming velocity. A detailed analysis revealed that the kinetic response was transient: after 3 min the velocity decreased to the speed of the former horizontal swimming at 1 g. Control experiments simulating the influence of vibration and hypergravity during launch of the rocket lead to the conclusion that the increase of the velocity during the parabolic flight was exclusively induced by the transition to 0 g. An increased velocity was also observed under the condition of simulated weightlessness on a fast-rotating clinostat microscope.

An account is given of approaches to gravireception, terminology mechanisms of responses to gravity as investigated and documented in the literature, and sensorimotor coupling properties in ciliates. Current theories and methods are discussed, and previously published experimental data on graviresponses are reviewed.

Currently, gene sequence genealogies of the Oligotrichea Bütschli, 1889 comprise only few species. Therefore, a cladistic approach, especially to the Oligotrichida, was made, applying Hennig's method and computer programs. Twenty-three characters were selected and discussed, i.e., the morphology of the oral apparatus (five characters), the somatic ciliature (eight characters), special organelles (four characters), and ontogenetic particulars (six characters). Nine of these characters developed convergently twice. Although several new features were included into the analyses, the cladograms match other morphological trees in the monophyly of the Oligotrichea, Halteriia, Oligotrichia, Oligotrichida, and Choreotrichida. The main synapomorphies of the Oligotrichea are the enantiotropic division mode and the de novo-origin of the undulating membranes. Although the sister group relationship of the Halteriia and the Oligotrichia contradicts results obtained by gene sequence analyses, no morphologic, ontogenetic or ultrastructural features were found, which support a branching of Halteria grandinella within the Stichotrichida. The cladistic approaches suggest paraphyly of the family Strombidiidae probably due to the scarce knowledge. A revised classification of the Oligotrichea is suggested, including all sufficiently known families and genera.

Although Tintinnopsis cylindrica Daday, 1887 is apparently widely distributed in the plankton of marine and brackish coastal waters, its ciliary pattern remained unknown. Without detailed knowledge of the cell morphology, however, the proposed synonymies cannot be proved. Hence, the cell and lorica features of T. cylindrica are redescribed from live and protargol-impregnated specimens collected in mixo-polyhaline basins at the German North Sea coast. An improved species diagnosis and a comprehensive unified terminology are provided. The somatic ciliary pattern of T. cylindrica is complex, comprising a ventral, dorsal, and posterior kinety as well as a right, left, and lateral ciliary field. Accordingly, the species differs from its congener T. cylindrata that has merely a right and left ciliary field and ventral organelles. On the other hand, the genera Codonella, Codonellopsis, Cymatocylis, Helicostomella, Leprotintinnus, and Stenosemella share this pattern. The oral primordium of T. cylindrica develops hypoapokinetally posterior to the lateral ciliary field as in Codonella cratera and Cymatocylis convallaria.

Fifty-six ciliate taxa, including three new species, were found in two soil samples from the Hoge Veluwe National Park in The Netherlands. A literature search showed that The Netherlands, Belgium and Denmark are terra incognita with respect to soil ciliates: only about 100 species have been recorded. Likely, a much greater number, including many undescribed species, can be found on more detailed investigations. Two of the three new species are described in detail. Keronopsis schminkei nov. spec. differs from the congeners by the nuclear apparatus and cirral pattern. Keronopsis wetzeli Wenzel, 1953 is neotypified with the Austrian population described by Berger and Foissner (1987). Apobryophyllum schmidingeri differs from the congeners by body shape, the macronucleus pattern (many nodules), the arrangement of the extrusomes, and various morphometric features. Scanning electron micrographs and protargol preparations of Enchelys polynucleata confirm earlier transmission electron microscopic data on the occurrence of oralized somatic monokinetids and the lack of a circumoral kinety. Extrusome length and morphology of the resting cysts are rather different in various populations of E. polynucleata, indicating high genetic diversity (subspecies?).

Six soil samples from natural and cultivated sites of Saudi Arabia were investigated for ciliate diversity, using the non-flooded Petri dish culture method, live observation, and silver impregnation. We identified 135 species, all new for the fauna of Saudi Arabia, of which seven were undescribed: Spathidium alqasabi nov. spec.; Enchelyodon alqasabi nov. spec.; Metauroleptus arabicus nov. gen., nov. spec.; Pseudohemisincirra arabica nov. gen., nov. spec.; Saudithrix terricola​ Berger, Al-Rasheid and Foissner, 2006; Oxytricha arabica nov. spec.; and Erimophrya monostyla nov. spec. Based on Spathidium alqasabi, S. seppelti foissneri​ Vd'ačný et al., 2006 and S. seppelti etoschense​ Foissner et al., 2002 are raised to species rank; for the latter, a new name is required to avoid homonymy: Spathidium fraterculum nov. nom. The new genus Metauroleptus, which possesses two long and two to three short ventral cirral rows, generates all dorsal kineties intrakinetally and produces caudal cirri exclusively in dorsal kinety 1. Metauroleptus belongs to the hypotrichs, while family classification remains doubtful. The same applies to the new hypotrich genus Pseudohemisincirra, which has frontoventral and transverse cirri, while buccal cirri and caudal cirri are absent. The number of species contained in Saudi Arabian soils, including sand dunes, is in the range reported from other regions of the earth, suggesting that ciliates are well adapted to dry habitats, possibly mainly by their ability to produce very resistant resting cysts, most surviving for a long time due to reduced metazoan predation.

We studied the morphology of four new dileptid ciliates, using standard methods. Dileptus microstoma, which was discovered in Benin (Africa), is outstanding in having a very small oral opening (~4 μm), an interrupted dorsal row of contractile vacuoles, and ampulliform extrusomes. Dileptus semiarmatus, which was discovered in Austria, possesses extrusomes only in the right posterior half of the proboscis and has very widely spaced circumoral and perioral kinetids. Dileptus longitrichus, which was discovered in Japan, is almost unique in having up to 15 μm long brush bristles and a row of contractile vacuoles each in ventral and dorsal side of body. Pseudomonilicaryon brachyproboscis, which was discovered in Greece, differs from the congeners by the narrowly ellipsoidal micronuclei, the dimorphic dorsal brush, the extrusomes, and the contractile vacuole pattern. Four new features are introduced for distinguishing species in dileptids: shape of micronucleus, monomorphic/dimorphic dorsal brush, shape of oral opening, and spacing of circumoral dikinetids. The terrestrial dileptids share several distinct morphological features that are probably adaptations to the soil environment: (1) the body is comparatively slender and small, what is likely related to the narrowness of the habitat; (2) the proboscis is short, which increases the relative volume of the trunk, what might be related to its fragility and/or to the space available for prey digestion; (3) the long dorsal bristles might foster prey recognition; and (4) the pronounced body flexibility in all dileptids likely fosters their high diversity in the narrow and wrinkled soil habitat.