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Morphology, Morphogenesis, and Molecular Phylogeny of a New Freshwater Ciliate, Quadristicha subtropica n. sp. (Ciliophora, Hypotrichia).

ABSTRACT: The morphology and the regulation of cortical pattern associated with the cell size, division, and phylogenetic position of a new hypotrichous ciliate, Quadristicha subtropica n. sp. collected from a freshwater pond in southern China, were investigated. Quadristicha subtropica n. sp. is characterized as follows: size in vivo 60-115 μm × 25-45 μm; 19-21 adoral membranelles; buccal cirrus near anterior end of endoral and paroral; cirrus IV/3 at about level of buccal vertex; right marginal row begins ahead of buccal vertex; 11-16 right and 12-19 left marginal cirri; and dorsal cilia about 5 μm long. The basic morphogenetic process in Q. subtropica n. sp. is consistent with that of the type species, Quadristicha setigera. Phylogenetic analyses based on small subunit ribosomal DNA sequence data reveal that the systematic position of Q. subtropica n. sp. is rather unstable with low support values across the tree and the genus Quadristicha is not monophyletic.

SUBMITTER: Shao C

PROVIDER: S-EPMC8319829 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Publications

Morphology, Morphogenesis, and Molecular Phylogeny of a New Freshwater Ciliate, Quadristicha subtropica n. sp. (Ciliophora, Hypotrichia).

Shao Chen C Gao Qi Q Warren Alan A Wang Jingyi J

Frontiers in microbiology 20210715

The morphology and the regulation of cortical pattern associated with the cell size, division, and phylogenetic position of a new hypotrichous ciliate, Quadristicha subtropica n. sp. collected from a freshwater pond in southern China, were investigated. Quadristicha subtropica n. sp. is characterized as follows: size in vivo 60-115 μm × 25-45 μm; 19-21 adoral membranelles; buccal cirrus near anterior end of endoral and paroral; cirrus IV/3 at about level of buccal vertex; ri ...[more]

PMID: 34335539

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Project description: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.

Project description:BackgroundCiliated 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.ResultsThe 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.ConclusionsThe 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.

Project description:Many anaerobic ciliated protozoa contain organelles of mitochondrial ancestry called hydrogenosomes. These organelles generate molecular hydrogen that is consumed by methanogenic Archaea, living in endosymbiosis within many of these ciliates. Here we describe a new species of anaerobic ciliate, Trimyema finlayi n. sp., by using silver impregnation and microscopy to conduct a detailed morphometric analysis. Comparisons with previously published morphological data for this species, as well as the closely related species, Trimyema compressum, demonstrated that despite them being similar, both the mean cell size and the mean number of somatic kineties are lower for T. finlayi than for T. compressum, which suggests that they are distinct species. This was also supported by analysis of the 18S rRNA genes from these ciliates, the sequences of which are 97.5% identical (6 substitutions, 1479 compared bases), and in phylogenetic analyses these sequences grouped with other 18S rRNA genes sequenced from previous isolates of the same respective species. Together these data provide strong evidence that T. finlayi is a novel species of Trimyema, within the class Plagiopylea. Various microscopic techniques demonstrated that T. finlayi n. sp. contains polymorphic endosymbiotic methanogens, and analysis of the endosymbionts' 16S rRNA gene showed that they belong to the genus Methanocorpusculum, which was confirmed using fluorescence in situ hybridization with specific probes. Despite the degree of similarity and close relationship between these ciliates, T. compressum contains endosymbiotic methanogens from a different genus, Methanobrevibacter. In phylogenetic analyses of 16S rRNA genes, the Methanocorpusculum endosymbiont of T. finlayi n. sp. grouped with sequences from Methanomicrobia, including the endosymbiont of an earlier isolate of the same species, 'Trimyema sp.,' which was sampled approximately 22 years earlier, at a distant (∼400 km) geographical location. Identification of the same endosymbiont species in the two separate isolates of T. finlayi n. sp. provides evidence for spatial and temporal stability of the Methanocorpusculum-T. finlayi n. sp. endosymbiosis. T. finlayi n. sp. and T. compressum provide an example of two closely related anaerobic ciliates that have endosymbionts from different methanogen genera, suggesting that the endosymbionts have not co-speciated with their hosts.

Dataset Information

Morphology, Morphogenesis, and Molecular Phylogeny of a New Freshwater Ciliate, Quadristicha subtropica n. sp. (Ciliophora, Hypotrichia).

Publications

Morphology, Morphogenesis, and Molecular Phylogeny of a New Freshwater Ciliate, <i>Quadristicha subtropica</i> n. sp. (Ciliophora, Hypotrichia).

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