From oral structure to molecular evidence:new insights into the evolutionary phylogeny of the ciliate order Sessilida(Protista,Ciliophora),with the establishment of two new families and new contributions to the poorly studied family Vaginicolidae

Ciliated protists represent one of the most primitive and diverse lineages of eukaryotes,with nuclear dimorphism,a distinctive sexual process(conjugation),and extensive genome rearrangements.Among divergent ciliate lineages,the peritrich order Sessilida includes members with a colonial lifestyle,which may hint to an independent evolutionary attempt for multicellularity,although they are still single-celled organisms.To date,the evolution and phylogeny of this group are still far from clear,in part due to the paucity of molecular and/or morphological data for many taxa.In this study,we extend taxon sampling of a loricate group of sessilids by obtaining 69 new r DNA(SSU r DNA,ITS1-5.8S rDNA-ITS2,and LSU r DNA)sequences from 20 wellcharacterized representative species and analyze the phylogenetic relationships within Sessilida.The main findings are:(i)the genera Rhabdostyla and Campanella each represents a unique taxon at family level,supporting the establishment of two new families,i.e.,Rhabdostylidae n.fam.and Campanellidae n.fam.,respectively,the former being sister to a morphologically heterogeneous clade comprising Astylozoidae and several incertae sedis species and the latter occupying the basal position within the Sessilida clade;(ii)the structure of infundibular polykinety 3 is likely to be a phylogenetically informative character for resolving evolutionary relationships among sessilids;(iii)differences between sparsely and the densely arranged silverline systems could be a suprageneric taxonomic character;(iv)the monophyly of Vaginicolidae is confirmed,which is consistent with its specialized morphology,i.e.,the possession of a typical peritrich lorica which might be an apomorphy for this group;(v)within Vaginicolidae,the monotypic Cothurniopsis sensu Stokes,1893 is a synonym of Cothurnia Ehrenberg,1831,and a new combination is created,i.e.,Cothurnia valvata nov.comb.;(vi)Vaginicola sensu lato comprises at least two distinctly divergent clades,one affiliated with Thuricola and the other with a systematically puzzling clade represented by Vaginicola tincta.

Morphology,taxonomy and molecular phylogeny of three marine peritrich ciliates,including two new species:Zoothamnium apoarbuscula n.sp.and Z.apohentscheli n.sp.(Protozoa,Ciliophora,Peritrichia)

Zoothamnium is a speciose genus,most species of which have incomplete morphological data based on modern criteria.In the present study,the morphology of three species of Zoothamnium,i.e.,Z.apoarbuscula n.sp.,Z.apohentscheli n.sp.,and Z.alternans,collected in Qingdao,China,was revealed using living observation and silver staining.In addition,the SSU rDNA of each species was sequeneed for phylogenetic analyses.Zoothamnium apoarbuscula n.sp.is characterized by its umbellate colony which is up to 900 pm high,dichotomously branched stalk,differentiation of zooids,and infundibular polykinety 3 comprising three equal-length ciliary rows.Zoothamnium apohentscheli n.sp is characterized by its large colony up to 1700 pm high,alternately branched stalk,and infundibular polykinety 3 comprising three equal-length ciliary rows.A population of Z.altenums is described in detail.Phylogenetic analyses based on SSU rDNA sequence data revealed that species with an alternately branched stalk cluster together in gene trees and probably represent an independent lineage within the genus Zoothamnium.

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.

Integrative studies on the taxonomy and molecular phylogeny of four new Pleuronema species(Protozoa,Ciliophora,Scuticociliatia)

The ciliate genus Pleuronema comprises approximately 30 nominal species and has been reported in freshwater,brackish water,and marine habitats.Nevertheless,recent studies have indicated that there might be a large undiscovered species diversity.In the present work,four new Pleuronema species,namely P.foissneri sp.nov.,P.parasmalli sp.nov.,P.parasalmastra sp.nov.,and P.paraorientale sp.nov.,collected from Shenzhen,southern China,was investigated using taxonomic methods.The diagnosis,description,comparisons with morphologically related species and detailed morphometric data are supplied for each.The small subunit ribosomal RNA(SSU rRNA)gene of the four new species is sequenced and their molecular phylogeny is analyzed.The SSU rRNA gene tree shows that Pleuronema is polyphyletic comprising several separate clades.All four new species cluster consistently with P.orientale KF206429,P.puytoraci KF840520 and P.setigerum FJ848874 within the core Pleuronematidae+Peniculistomatidae clade.Phylogenies of Pleuronematidae-related taxa are also discussed.

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.