Redescription of Keronopsis helluo Penard, 1922 from Antarctica and Paraholosticha pannonica Gellért and Tamás, 1959 from Alaska (Ciliophora, Hypotricha)

Morphological, ontogenetic, and phylogenetic research of a poorly known non-dorsomarginalian ciliate: Erniella filiformis Foissner, 1987 (Protista, Ciliophora, Hypotrichia)

Erniella Foissner, 1987 is a poorly known genus with its available information limited solely to morphological characteristics. In this study, the type species E. filiformis, isolated from highly saline water in China, was investigated for morphology, morphogenesis, and phylogeny based on small subunit ribosomal DNA sequences. The main characteristic events during morphogenesis in Erniella filiformis are as follows: (1) in the proter, only the posterior part of the parental adoral zone is renewed and undulating membranes anlage is formed from the dedifferentiation of the old structure; (2) the oral primordium is formed intrakinetally in the opisthe; (3) frontoventral-transverse cirral anlagen II-IV develop in the primary mode, anlage V develops intrakinetally in the proter; and (4) the right frontoventral row is formed by a single anlage. The phylogenetic analyses indicate that Erniella forms a monophyletic group with Bistichella, Keronopsis, Lamtostyla, Orthoamphisiella, Parabistichella, Paraholosticha, and Uroleptoides.

Morphology, morphogenesis and molecular phylogeny of Lamtostyla granulifera sinensis subsp. nov. (Ciliophora, Hypotrichia) from a wetland in China

The morphology, morphogenesis and molecular phylogeny of a hypotrichous ciliate, Lamtostyla granulifera sinensis subsp. nov., isolated from northern China, were investigated. This population appeared highly similar in morphology to L. granulifera Foissner, 1997. However, on detailed investigation some non-overlapping features were identified, i.e., the body shape and the arrangement of the cortical granules. These differences suggested the separation at subspecies level. Furthermore, the morphogenesis of the new subspecies is described, which is characterized by: (1) the posterior part of the parental adoral zone of membranelles is renewed; (2) the amphisiellid median cirral row is formed from two anlagen; and (3) the frontoventral-transverse cirral anlagen II to VI generate one transverse cirrus each. Phylogenetic analyses based on SSU rDNA sequence data show that Lamtostyla species are scattered in different clades. The monophyly of the genus Lamtostyla is also rejected by the AU test in this study.

Phylogeny of a new ciliate family Clampidae fam. nov. (Protista: Ciliophora), with notes on morphology and morphogenesis

Hypotrichs comprise a highly differentiated and diversified group of ciliates with an evolutionary history characterized by an exceptional number of convergences and reversions. A new hypotrich ciliate from a freshwater fishpond is investigated based on morphological, morphogenetic and molecular data. The phylogenetic analyses reveal that the new species is closely related to Simplicitergida despite the absence of zigzag-patterned midventral cirral pairs, a common feature of simplicitergids. The phylogenetic position of this atypical simplicitergid species is strongly supported by the conserved features of dorsal ciliature and nuclear apparatus, which are probably more informative than cirral patterns for higher-rank classification. The close phylogenetic relationships among those Simplicitergida with varied cirral patterns could be explained by evolutionary convergences and reversions. The new species is recognized mainly by three frontoventral rows, several short midventral rows, two long midventral rows and the absence of zigzag-patterned midventral cirral pairs. Based on comprehensive phylogenetic analyses, together with detailed morphological and morphogenetic comparisons, a new family, Clampidae fam. nov., is proposed for the new genus and species, Clampia sinica gen. et sp. nov. In addition, an emended diagnosis of the morphologically similar family Epiclintidae is provided.

Phagotrophic protists (protozoa) in Antarctic terrestrial ecosystems: diversity, distribution, ecology, and best research practices

Phagotrophic protists (formerly protozoa) are a highly diverse, polyphyletic grouping of generally unicellular, heterotrophic eukaryotes that are key regulators of the soil microbiome. The biodiversity and ecology of soil phagotrophic protists are still largely uncharacterized, especially in the Antarctic, which possesses some of the harshest terrestrial environments known and potentially many physiologically unique and scientifically interesting species. Antarctic soil systems are also highly limited in terms of moisture, temperature, and carbon, and the resulting reduced biological complexity can facilitate fine-tuned investigation of the drivers and functioning of microbial communities. To facilitate and encourage future research into protist biodiversity and ecology, especially in context of the broader functioning of Antarctic terrestrial communities, I review the biodiversity, distribution, and ecology of Antarctic soil phagotrophic protists. Biodiversity appears to be highly structured by region and taxonomic group, with the Antarctic Peninsula having the highest taxonomic diversity and ciliates (Ciliophora) being the most diverse taxonomic group. However, richness estimates are likely skewed by disproportionate sampling (over half of the studies are from the peninsula), habitat type bias (predominately moss-associated soils), investigator bias (toward ciliates and the testate amoeba morphogroup), and methodological approach (toward cultivation and morphological identification). To remedy these biases, a standardized methodology using both morphological and molecular identification and increased emphasis on microflagellate and naked amoeba morphogroups is needed. Additionally, future research should transition away from biodiversity survey studies to dedicated ecological studies that emphasize the function, ecophysiology, endemicity, dispersal, and impact of abiotic drivers beyond moisture and temperature.

Cell-division pattern and phylogenetic analyses of a new ciliate genus Parasincirra n. g. (Protista, Ciliophora, Hypotrichia), with a report of a new soil species, P. sinica n. sp. from northwest China

Background

Ciliated protists, a huge assemblage of unicellular eukaryotes, are extremely diverse and play important ecological roles in most habitats where there is sufficient moisture for their survivals. Even though there is a growing recognition that these organisms are associated with many ecological or environmental processes, their biodiversity is poorly understood and many biotopes (e.g. soils in desert areas of Asia) remain largely unknown. Here we document an undescribed form found in sludge soil in a halt-desert inland of China. Investigations of its morphology, morphogenesis and molecular phylogeny indicate that it represents a new genus and new species, Parasincirra sinica n. g., n. sp.

Results

The new, monotypic genus Parasincirra n. g. is defined by having three frontal cirri, an amphisiellid median cirral row about the same length as the adoral zone, one short frontoventral cirral row, cirrus III/2 and transverse cirri present, buccal and caudal cirri absent, one right and one left marginal row and three dorsal kineties. The main morphogenetic features of the new taxon are: (1) frontoventral-transverse cirral anlagen II to VI are formed in a primary mode; (2) the amphisiellid median cirral row is formed by anlagen V and VI, while the frontoventral row is generated from anlage IV; (3) cirral streaks IV to VI generate one transverse cirrus each; (4) frontoventral-transverse cirral anlage II generates one or two cirri, although the posterior one (when formed) will be absorbed in late stages, that is, no buccal cirrus is formed; (5) the posterior part of the parental adoral zone of membranelles is renewed; (6) dorsal morphogenesis follows a typical Gonostomum-pattern; and (7) the macronuclear nodules fuse to form a single mass. The investigation of its molecular phylogeny inferred from Bayesian inference and Maximum likelihood analyses based on small subunit ribosomal DNA (SSU rDNA) sequence data, failed to reveal its exact systematic position, although species of related genera are generally assigned to the family Amphisiellidae Jankowski, 1979. Morphological and morphogenetic differences between the new taxon and Uroleptoides Wenzel, 1953, Parabistichella Jiang et al., 2013, and other amphisiellids clearly support the validity of Parasincirra as a new genus. The monophyly of the family Amphisiellidae is rejected by the AU test in this study.

Conclusions

The critical character of the family Amphisiellidae, i.e., the amphisiellid median cirral row, might result from convergent evolution in different taxa. Amphisiellidae are not monophyletic.

Systematic Redefinition of the Hypotricha (Alveolata, Ciliophora) Based on Combined Analyses of Morphological and Molecular Characters

The systematics of Hypotricha is one of the most puzzling problems in ciliate biology, having spanned numerous conflicting hypotheses with unstable relationships at various levels in molecular trees, for which the constant addition of newly discovered species has only increased the confusion. The hypotrichs comprise a remarkable morphologically diversified group of ciliates, and the phylogenetic potential of morphological traits is generally recognized. However, such characters were rarely used in phylogenetic reconstructions, and congruence with molecular data never assessed from simultaneous analyses. To properly reconciliate morphological and molecular information, maximum-likelihood and parsimony analyses of 79 morphological characters and 18S rDNA sequences were performed for 130 ingroup terminals, broadly sampled to represent the known hypotrich diversity. As result, well-supported and relatively stable clades were recovered, based on which the redefined Hypotricha comprises at least six higher taxa: The "arcuseriids", Holostichida, Parabirojimida, and the "amphisiellids", plus the two large clades Kentrurostylida nov. tax. (Hispidotergida nov. tax. and Simplicitergida nov. tax.) and Diatirostomata nov. tax. ("bistichellids", "kahliellids", Gonostomatida and Dorsomarginalia [Postoralida nov. tax. and Uroleptida]). Each taxon was circumscribed by synapomorphies, of which most were homoplastic, as the natural history of hypotrichs is portrayed by an outstanding quantity of convergences and reversions.

An Integrative Investigation of Parabistichella variabilis (Protista, Ciliophora, Hypotrichia) Including Its General Morphology, Ultrastructure, Ontogenesis, and Molecular Phylogeny

Hypotrichs are a highly differentiated and very diverse group of ciliated protists. Their systematics and taxonomy are challenging and call for detailed investigations on their general morphology, ultrastructure, ontogenesis, and molecular phylogeny. Here, a comprehensive study is conducted on a brackish water population of Parabistichella variabilis using light and electron microscopy and phylogenetic analyses based on small subunit ribosomal DNA sequence data. Its morphology, including the infraciliature, pellicle, nuclei, buccal seal, and extrusomes, is documented. The present findings indicate that in P. variabilis: (i) the cortical granules are extrusomes, which differ from those of other hypotrichs; (ii) the buccal seal is bounded by the plasma membrane and contains a single layer of longitudinal microtubules; (iii) two contractile vacuoles might be present rather than one; and (iv) the pharyngeal disks are bounded by a single membrane. Early-to-middle stages of ontogenesis are described for the first time, enabling the complete characterization of this process. Phylogenetic analyses indicate that Parabistichella variabilis is closely related to several species from different genera, such as Orthoamphisiella breviseries, Uroleptoides magnigranulosus, and Tachysoma pellionellum. However, ultrastructural and gene sequence data for more taxa are needed in order to resolve the systematics of Parabistichella.