Monophyly or polyphyly? Possible conflict between morphological and molecular interpretations of the wellknown genus Zoothamnium(Ciliophora,Peritrichia)

In this paper, we explore possible conflict between morphological and molecular interpretations of phylogenetic relationships within the well-known peritrichous genus Zoothamnium. On the basis of morphological evidence, for a long time this genus has been believed to be a well-defined monophyletic taxon. Nonetheless, Zoothamnium exhibits higher genetic diversity than the gross morphology of its species. Here, we used all available genetic information for the small subunit of ribosomal RNA （SSU rRNA） and internal transcribed spacer region （ITS1-5.8S-ITS2） for this genus to reconstruct phylogenies for four datasets （SSU rRNA, ITS1, ITS2, and ITS1-5.8S-ITS2） and a combined dataset （SSU rRNA＋ITSI-5.8S- ITS2） using different phylogenetic methods and with consideration of the secondary structure of the genes. Confidence in phylogenetic tree selection was assessed with the approximately unbiased test. The molecular results showed both that Zoothamnium is more likely to be polyphyletic, and morphologically similar genera Zoothamnopsis and Myoschiston were always nested among Zoothamnium species. Accordingly, as with some other groups of ciliates, to understand more fully the correct phylogeny of Zoothamnium there remains a need for additional data from both morphological and molecular studies, covering additional Zoothamnium spp. and members of closely related genera （e.g. Zoothamnopsis, Myoschiston, and Epistylis）.

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.