Taxonomic description of a new marine ciliate,Euplotes qingdaoensis n. sp.(Ciliophora:Euplotida)

The characteristics and infraciliature of a new euplotid ciliate,Euplotes qingdaoensis n.sp.,discovered from the coastal waters of Jiaozhou Bay,northern China,were studied using live observation and silver impregnation.The new marine species is characterized by a slightly fl attened body(90–110 μm×70–80 μm,in vivo),an adoral zone of 26–29 membranelles,10 strong frontoventral and fi ve transverse cirri,two caudal cirri,a single left marginal cirrus,seven dorsal kineties,a middle kinety with about 15 pairs of basal bodies,a silverline system of the double-eurystomus type,and a C-shaped macronucleus.

Insights into the phylogeny of sporadotrichid ciliates (Protozoa, Ciliophora: Hypotricha) based on genealogical analyses of multiple molecular markers

The sporadotrichid ciliates are an especially diverse group. A number of investigators have studied the morphological, morphogenetic, and molecular relationships among members of this group. Despite this, a consistent classification is still lacking and several important questions about the phylogenetic relationships within this group remain unsolved. To improve our understanding of these relationships, we constructed phylogenetic trees using the nucleotide sequences of the small-subunit rRNA (SSrRNA) gene and amino acid sequences of actin I and α-tubulin. Analyses of SSrRNA gene sequences indicated that: 1) the Sporadotrichida sensu Lynn (2008) and the Oxytrichidae are polyphyletic; 2) the Uroleptus species, which are classified to urostylids, formed a sister group with the oxytrichids; 3) Halteria grandinella, which is grouped morphologically with oligotrich species, clustered within the oxytrichids. These results are congruent with previous studies based on SSrRNA gene sequences. However, the amino acid sequences of actin I and α-tubulin yielded different topologies. The main results are: 1) in all phylogenetic trees, the genus Oxytricha was paraphyletic; 2) Uroleptus was sister to a subset of Urostyla and Holosticha, albeit with low supporting values; 3) Halteria grandinella was separated distantly from the Oxytrichidae in trees inferred from actin I amino acid sequences but clustered with oligotrichids in the α-tubulin analysis. The inconsistency among the trees inferred from these different molecular markers may be caused by rapidly accumulated genetic characterizations of ciliates. Further studies with additional molecular markers and sampling of more taxa are expected to better address the relationships among sporadotrichids.

Phylogeny of subclass Scuticociliatia(Protozoa,Ciliophora) using combined data inferred from genetic,morphological,and morphogenetic evidence

Gene sequence-based genealogies of scuticociliates are different from those produced by morphological analyses.For this reason,11 representative scuticociliates and two ambiguously related genera were chosen to test the ability of combined phylogenetic analyses using both gene sequences and morphological/morphogenetic characteristics.Analyses of both the SSrRNA gene sequences and the combined datasets revealed a consistent branching pattern.While the terminal branches and the order level relationships were generally well resolved,the family level relationships remain unresolved.However,two other trees based on ITS1-5.8S-ITS2 region sequences and morphological/morphogenetic characters showed limited information,due to a lack of informative sites in these two datasets.Our data suggest,however,that the combined analysis of morphological/morphogenetic characters and gene sequences did produce some changes to the phylogenetic estimates of this group.

Molecular Phylogenetic Lineage of Plagiopogon and Askenasia(Protozoa, Ciliophora) Revealed by Their Gene Sequences

Prostomates and haptorians are two basal groups of ciliates with limited morphological characteristics available for taxonomy. Morphologically, the structures used to identify prostomates and haptorians are similar or even identical, which generate heavy taxonomic and phylogenetic confusion. In present work, phylogenetic positions lineage of two rare genera, Plagiopogon and Askenasia, were investigated. Three genes including small subunit ribosomal RNA gene(hereafter SSU r DNA), internal transcribed spacer region(ITS region), and large subunit ribosomal RNA gene(LSU r DNA) were analyzed, 10 new sequences five species each. Our findings included 1) class Prostomatea and order Haptorida are multiphyletic; 2) it may not be appropriate to place order Cyclotrichiida in subclass Haptoria, and the systematic lineage of order Cyclotrichiida needs to be verified further; 3) genus Plagiopogon branches consistently within a clade covering most prostomes and is basal of clade Colepidae, implying its close lineage to Prostomatea; and 4) Askenasia is phylogenetically distant from the subclass Haptoria but close to classes Prostomatea, Plagiopylea and Oligohymenophorea. We supposed that the toxicyst of Askenasia may be close to taxa of prostomes instead of haptorians, and the dorsal brush is a more typical morphological characteristics of haptorians than toxicysts.

On four epibiotic peritrichous ciliates(Protozoa,Ciliophora)found in Lake Weishan Wetland:morphological and molecular data support the establishment of a new genus,Parapiosoma gen.nov.,and two new species

During a study on the diversity of ciliated protists in Lake Weishan Wetland,the largest wetland in northern China,four epibiotic sessilid peritrichs were isolated from aquatic host animals.Two of them,i.e.,Epistylis cambari Kellicott,1885 and Epistylis lwof Fauré-Fremiet,1943,were known species whereas the other two,i.e.,Parapiosoma typicum gen.nov.,sp.nov.and Orborhabdostyla gracilis sp.nov.,are new to science.The new genus Parapiosoma gen.nov.is characterized by its branched non-contractile stalk,everted peristomial lip,obconical macronucleus and transverse silverlines.Two species are assigned to the new genus,namely Parapiosoma typicum sp.nov.and Parapiosoma gasterostei(Fauré-Fremiet,1905)comb.nov.Morphologically,P.typicum sp.nov.is recognized by its goblet-shaped zooids,single-layered peristomial lip,dichotomously branched stalk,and infundibular polykinety 3(P3)containing three equal-length rows.Orborhabdostyla gracilis sp.nov.is characterized by its slender zooid,curved macronucleus,and three equal-length rows in infundibular P3.Improved diagnoses and redescriptions of E.cambari and E.lwof are provided including,for the frst time,data on the ciliature of E.cambari.Phylogenetic analyses based on SSU rDNA,ITS1-5.8S rDNA-ITS2,and LSU rDNA sequence data strongly support the assertion that the family Epistylididae comprises morphospecies with diferent evolutionary lineages and indicate that Parapiosoma gen.nov.may represent a new taxon at family level.

Nuclear events during conjugation in the poorly studied model ciliate Paramecium jenningsi

Ciliated protists are highly differentiated unicellular eukaryotes that possess special sexual processes(conjugation and autogamy)that rely on their unique nuclear dimorphism,i.e.,the presence of both a germline micronucleus(MIC)and a somatic macronucleus(MAC)in a single cell.The sexual processes show a high diversity in different ciliates.To better understand the differentiation and evolution of sexual processes in closely related species,we investigated the nuclear events during conjugation in Paramecium jenningsi strain GZ,a poorly studied close relative of the well-known P.aurelia complex.The main results include:(1)the conjugation process takes about 48 h,including three prezygotic divisions(meiosis I,II,and mitosis)and three postzygotic divisions;(2)the MICs are dominated by the“parachute”phase at the prophase of meiosis I;(3)after meiosis II,a variable number of nuclei undergo the third prezygotic division,and the two products near the paroral cone become the genetically identical migratory and stationary pronuclei;(4)the synkaryon divides three times to form the MIC and the MAC anlagen,but only one nuclear product of the first postzygotic division completes the next two divisions;and(5)an extra cell division is required to complete the last step of conjugation,during which two MIC anlagen undergo mitotic division while two MAC anlagen are distributed between the daughter cells without division.The comparison of the nuclear events during conjugation in representatives of the class Oligohymenophorea reveals that usually there are three prezygotic divisions and a variable number of postzygotic divisions.However,the number of selected and differentiated nuclei after each division differs among species.This study provided a new model ciliate for further investigations of nuclear selection and differentiation as well as nuclear morphology during meiosis.

Biodiversity of freshwater ciliates(Protista,Ciliophora)in the Lake Weishan Wetland,China:the state of the

Ciliates are core components of the structure of and function of aquatic microbial food webs.They play an essential role in the energy flow and material circulation within aquatic ecosystems.However,studies on the taxonomy and biodiversity of freshwater ciliates,especially those in wetlands in China are limited.To address this issue,a project to investigate the freshwater ciliates of the Lake Weishan Wetland,Shandong Province,commenced in 2019.Here,we summarize our findings to date on the diversity of ciliates.A total of 187 ciliate species have been found,94 of which are identified to species-level,87 to genus-level,and six to family-level.These species show a high morphological diversity and represent five classes,i.e.,Heterotrichea,Litostomatea,Prostomatea,Oligohymenophorea,and Spirotrichea.The largest number of species documented are oligohymenophoreans.A comprehensive database of these ciliates,including morphological data,gene sequences,microscope slide specimens and a DNA bank,has been established.In the present study,we provide an annotated checklist of retrieved ciliates as well as information on the sequences of published species.Most of these species are recorded in China for the first time and more than 20%are tentatively identified as new to science.Additionally,an investigation of environmental DNA revealed that the ciliate species diversity in Lake Weishan Wetland is higher than previously supposed.

New considerations on the phylogeny of Sessilida(Protista:Ciliophora:Peritrichia)based on multiple-gene information,with emphasis on colonial taxa

The subclass Peritrichia,containing two orders Sessilida and Mobilida,is a major group of ciliates with worldwide distribution and high species diversity.Several studies have investigated the phylogeny of peritrichs;however,the evolutionary relationships and classification of some families and genera within the Sessilida remain unclear.In the present study,we isolated and identified 22 peritrich populations representing four families and six genera and obtained 64 rDNA sequences to perform phylogenetic analyses and assess their systematic relationships.Ancestral character reconstruction was also carried out to infer evolutionary routes within the Sessilida.The results indicate:(1)family Vaginicolidae is monophyletic and acquisition of the typical peritrich lorica represents a single evolutionary divergence;(2)core epistylidids evolved from a Zoothamnium-like ancestor and experienced spasmoneme loss during evolution;(3)Campanella clusters with species in the basal clade and shows stable morphological differences with other epistylidids,supporting its assignment to a separate family;(4)the structure of the peristomial lip may be a genus-level character rather than a diagnostic character for discriminating Epistylididae and Operculariidae,thus a redefinition of Operculariidae should be carried out when more species have been investigated;(5)some characters,such as lifestyle(solitary or colonial),spasmoneme and living habit(sessile or free-swimming),evolved repeatedly among sessilids indicating that species with non-contractile stalks or that are free-swimming have multiple evolutionary routes and might derive from any sessilid lineage without a lorica.The close phylogenetic relationships of some morphologically distinct sessilids imply that the diagnoses of some genera and families should be improved.