The All-Data-Based Evolutionary Hypothesis of Ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata)

Abstract

The phylum Ciliophora plays important roles in a wide range of biological studies. However, the evolutionary relationships of many groups remain unclear due to a lack of sufficient molecular data. In this study, molecular dataset was expanded with representatives from 55 orders and all major lineages. The main findings are: (1) 14 classes were recovered including one new class, Protocruziea n. cl.; (2) in addition to the two main branches, Postciliodesmatophora and Intramacronucleata, a third branch, the Mesodiniea, is identified as being basal to the other two subphyla; (3) the newly defined order Discocephalida is revealed to be a sister clade to the euplotids, strongly suggesting the separation of discocephalids from the hypotrichs; (4) the separation of mobilids from the peritrichs is not supported; (5) Loxocephalida is basal to the main scuticociliate assemblage, whereas the thigmotrichs are placed within the order Pleuronematida; (6) the monophyly of classes Phyllopharyngea, Karyorelictea, Armophorea, Prostomatea, Plagiopylea, Colpodea and Heterotrichea are confirmed; (7) ambiguous genera Askenasia, CyclotrichiumParaspathidium and Plagiocampa show close affiliation to the well known plagiopyleans; (8) validity of the subclass Rhynchostomatia is supported, and (9) the systematic positions of Halteriida and Linconophoria remain unresolved and are thus regarded as incertae sedis within Spirotrichea.

Constraints on Phylogenetic Interrelationships among Four Free-living Litostomatean Lineages Inferred from 18S rRNA gene-ITS Region sequences and Secondary Structure of the ITS2 molecule

“…However, the evolutionary interrelationships among the haptorian orders are very poorly resolved and understood (e.g. Zhang et al 2012;Vďačný et al 2014;Gao et al 2016;Vďačný and Rataj 2017).…”

Enzymatic and chemical mapping of nucleosome distribution in purified micro- and macronuclei of the ciliated model organism, Tetrahymena thermophila

“…Tetrahymena thermophila is a well-established unicellular eukaryotic model organism ( Figure 1A-F) (Chen et al, 2015;Gao et al, 2016;Karrer, 1999). Like most ciliates, Tetrahymena exhibits nuclear dimorphism, containing one micronucleus (MIC) and one macronucleus (MAC) in the same cell compartment ( Figure 1F) (Karrer, 2012).…”

A Huge Diversity of Metopids (Ciliophora, Armophorea) in Soil from the Murray River Floodplain, Australia. II. Morphology and Morphogenesis of Lepidometopus platycephalus nov. gen., nov. spec.

“…On the other hand, the armophorid family Caenomorphidae Poche, 1913 could be a sister group of the "Metopidae + Clevelandellida" cluster or, more likely, could have diverged at the base of the Spirotrichea or the Intramacronucleata (Paiva et al 2013). Thus, the class Armophorea is very likely non-monophyletic with caenomorphids not being closely related to metopids + clevelandellids within the "SAL" (Spirotrichea + Armophorea + Litostomatea) supercluster recognized from extensive molecular datasets (Gentekaki et al 2014(Gentekaki et al , 2017Gao et al 2016).…”