Description of two marine amphisiellid ciliates, Amphisiella milnei (Kahl, 1932) Horváth, 1950 and A. sinica sp. nov. (Ciliophora: Hypotrichia), with notes on their ontogenesis and SSU rDNA-based phylogeny

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.

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.

Two Urosoma species (Ciliophora, Hypotrichia): A multidisciplinary approach provides new insights into their ultrastructure and systematics

The general morphology and ultrastructure of two soil hypotrichous ciliates, Urosoma emarginata and U. salmastra, were investigated using light microscopy, scanning electron microscopy and transmission electron microscopy. Phylogenetic analyses, based on the newly sequenced small subunit ribosomal (SSU) rRNA genes, were conducted on three U. emarginata populations and one U. salmastra population. Our findings support for the validity of Perilemmaphora Berger, 2008, a rankless taxon comprising spirotrich ciliates having a perilemma. The cortical granules of both species are extrusomes representing a new type of mucocyst in U. emarginata and possibly a new type of pigmentocyst in U. salmastra. Additionally, the lithosomes were revealed as subglobose structures composed of a low electron-dense, homogeneous inner part and an electron-dense outer part. The ultrastructural features of the cortical granules, together with ontogenetic and molecular phylogenetic data, suggest that the genus Urosoma might need to be divided. It is posited that ultrastructural features of hypotrichous ciliates in general may have important taxonomic value warranting further investigation.

Morphology and Morphogenesis of a Novel Saline Soil Hypotrichous Ciliate, Gonostomum sinicum nov. spec. (Ciliophora, Hypotrichia, Gonostomatidae), Including a Report on the Small Subunit rDNA Sequence

Morphology, cirral pattern, and morphogenesis of the new saline soil hypotrich, Gonostomum sinicum nov. spec. collected from Longfeng Wetland in Daqing, north China, were studied, using detailed live observations and protargol-stained specimens. The new species is characterized as follows: (i) a size in vivo of 100-125 × 30-40 μm, (ii) colorless cortical granules, 0.5 μm across, arranged in short rows, (iii) an adoral zone composed of 28-33 membranelles, (iv) three or four frontoventral rows, one of which extends onto the postoral area, (v) left and right marginal rows composed of 18-27 and 21-35, cirri, respectively, and (vi) usually two transverse cirri. Morphogenesis is as usual for the genus Gonostomum, i.e. the cirral primordia II-VI are primary primordia which split into two sets for proter and opisthe in division middle stages, except for anlage I which develops independently. However, the number of frontoventral transverse anlagen is either five or six not only in different individuals but even in proter and opisthe of the same divider. The phylogenetic analyses based on SSU rDNA sequences showed that the genus Gonostomum is nonmonophyletic, indicating that the patterns of cirri and dorsal kineties are homoplasious characters. The new species G. sinicum nov. spec. is perhaps closely related to Cotterillia bromelicola and two congeners.