Ontogeny And Phylogeny Of Hypotrichia Ciliates(Protozoa, Ciliophora)

Ciliated protozoa, which are the most complex and highly differentiated groupamong single-celled organisms, with the unique conjugation pattern and specialnuclear dualism, are important in the research fields of cell biology, development andevolution. Recently, it is one of the most active research areas of Protozoology, thatusing modern microscopic observation in vivo and silver-staining technique, toinvestigate the morphological identification of the long-term confused groups, toclarity the confusion and carry out the ontogenetic processes, and to explore thephylogenetic and evolutionary relationships among ciliated protozoa combing withmolecular data.During2007to2011, the work is including fauna survey of ciliated protozoa inthe mangrove, estuary, freshwater and soil habitats along the coasts of Yellow Sea(northern China) and South China Sea. It is mainly focused on the hypotrichousciliates (urostylids, stichotrichids and oxytrichids), which are the most complex groupin Ciliophora and significant in cell development and evolutionary phylogeny. Severalnew taxa are established, detailed redescription is carried out, unknown ontogeneticprocesses are newly investigated, new sequences data for small subunit (SSU) rRNAgene are deposited in GenBank and the secondary structures for RNA are constructed.For accurate identification among species and definition on the family and genus levelof key taxa, as well as resolution for controversial phylogenetic problems andrebuilding more reasonable system, it is providing comprehensive support informationfrom morphological, ontogenetic and molecular systematic data.The main achievements are following：1）Morphogenetic part:The twelve important, representative and significant species are selected in celldifferentiation, in taxa evolution and in phylogenetic evolution, from the unknowngroups, which own different ontogenetic patterns in three orders and six families. Thenew information during the ontogenetic processes for twelve species in nine genera(Bakuella, Metaurostylopsis, Pseudokeronopsis, Pseudourostyla, Amphisiella,Strongylidium, Rigidohymena, Rubrioxytricha and Sterkiella) is revealed and a seriesof uncertainties are clarified.Comparing and analyzing the ontogenetic characteristics among the taxa in thefamilies or sub-families, morphogenetic data are investigated as the importantsupportive references, to question the monophyly of Pseudokeronopsidae and Bakuellidae, to clarify the phylogenetic relationships among the morphologicalrelated genus of Strongylidium, and to support the establishment of Rigidohymena andits systematic position in the sub-family Stylonychinae.2）Phylogenetic and systematic part:The small subunit (SSU) rRNA gene sequences from ten genera and thirteenspecies are submitted to the GenBank for the first time. On this basis, thephylogenetic trees are constructed, the special regions in alignment are compared, andthe putative secondary structures of RNA are predicted. Using all availablemorphologic, ontogenetic and molecular data to analyze, the familyPseudokeronopsidae is redefined and the genera Thigmokeronopsis andApokeronopsis are removed out to the family Urostylidae. For the SSU rRNA genesequences for Amphisiella and Cyrtohymena from GenBank, their morphological dataare tracked and the molecular data from cryptic species are recognized.Based on the morphological, ontogenetic and molecular data of urostylid ciliatesfrom previous researches and myself, selecting characteristics from bothmorphological and ontogenetic and distinguishing the apomorph or plesiomorph ofthem, an assessment of phylogenetic relationships is given. Meanwhile, it is the firsttime to apply this particular analysis method combined with molecular phylogeneticinformation, to help rebuild new system and explore the phylogenetic relationshipamong the urostylid ciliates.3）Taxonomic part:As an additional result, one new genus（Monocoronella）and ten new species(Bakuella subtropica, Metaurostylopsis cheni, Monocoronella carnea, Monocoronelladragescoi, Pseudokeronopsis erythrina, Pseudourostyla saltans, Amphisiella pulchra,Amphisiella candida, Strongylidium orientale and Sterkiella subtropica) areestablished. And the detailed redescription for four species (Pseudourostyla cristata,Pseudourostyla nova, Rigidohymena candens and Rubrioxytricha haematoplasma) iscarried out.It supplies the biodiversity information of hypotrichous ciliates from differenthabitats, clarifies much confusion, and determines new definitions among genera andspecies.