Molecular phylogeny and comparative morphology indicate that odontostomatids (Alveolata, Ciliophora) form a distinct class-level taxon related to Armophorea (original) (raw)
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Phylogenetic study of Class Armophorea (Alveolata, Ciliophora) based on 18S-rDNA data
Genetics and Molecular Biology, 2013
The 18S rDNA phylogeny of Class Armophorea, a group of anaerobic ciliates, is proposed based on an analysis of 44 sequences (out of 195) retrieved from the NCBI/GenBank database. Emphasis was placed on the use of two nucleotide alignment criteria that involved variation in the gap-opening and gap-extension parameters and the use of rRNA secondary structure to orientate multiple-alignment. A sensitivity analysis of 76 data sets was run to assess the effect of variations in indel parameters on tree topologies. Bayesian inference, maximum likelihood and maximum parsimony phylogenetic analyses were used to explore how different analytic frameworks influenced the resulting hypotheses. A sensitivity analysis revealed that the relationships among higher taxa of the Intramacronucleata were dependent upon how indels were determined during multiple-alignment of nucleotides. The phylogenetic analyses rejected the monophyly of the Armophorea most of the time and consistently indicated that the Metopidae and Nyctotheridae were related to the Litostomatea. There was no consensus on the placement of the Caenomorphidae, which could be a sister group of the Metopidae + Nyctorheridae, or could have diverged at the base of the Spirotrichea branch or the Intramacronucleata tree.
Molecular Phylogeny of the Cyrtophorid Ciliates (Protozoa, Ciliophora, Phyllopharyngea)
2012
Evolutionary relationships of cyrtophorian ciliates are poorly known because molecular data of most groups within this subclass are lacking. In the present work, the SS rRNA genes belonging to 17 genera, 7 families of Cyrtophoria were sequenced and phylogenetic trees were constructed to assess their inter-generic relationships. The results indicated: (1) the assignment of cyrtophorians into two orders is consistently confirmed in all topologies; (2) the order Dysteriida is an outlined monophyletic assemblage while Chlamydodontida is paraphyletic with three separate monophyletic families; (3) Microxysma, which is currently assigned within the family Hartmannulidae, should be transferred to the family Dysteriidae; (4) the systematic position of Plesiotrichopidae remains unclear, yet the two genera that were placed in this family before, Pithites and Trochochilodon, should be transferred to Chlamydodontida; (5) a new family, Pithitidae n. fam., based on the type genus Pithites was suggested; and (6) the sequence of Isochona sp., the only available data of Chonotrichia so far, is probably from a misidentified species. In addition, three group I introns of SS rRNA gene were discovered in Aegyriana oliva, among which Aol.S516 is the first IE group intron reported in ciliates.
Journal of Eukaryotic Microbiology, 2009
ABSTRACT. Based on its characteristic oral apparatus, the ciliate subclass Peritrichia has long been recognized as a monophyletic assemblage composed of the orders Mobilida and Sessilida. Following the application of molecular methods, the monophyly of Peritrichia has recently been questioned. We investigated the phylogenetic relationships of the peritrichous ciliates based on four further complete small subunit ribosomal RNA sequences of mobilids, namely Urceolaria urechi, Trichodina meretricis, Trichodina sinonovaculae, and Trichodina ruditapicis. In all phylogenetic trees, the mobilids never clustered with the sessilids, but instead formed a monophyletic assemblage related to the peniculines. By contrast, the sessilids formed a sister clade with the hymenostomes at a terminal position within the Oligohymenophorea. We therefore formally separate the mobilids from the sessilids (Peritrichia sensu stricto) and establish a new subclass, Mobilia Kahl, 1933, which contains the order Mobilida Kahl, 1933. We argue that the oral apparatus in the mobilians and sessilid peritrichs is a homoplasy, probably due to convergent evolution driven by their similar life-styles and feeding strategies. Morphologically, the mobilians are distinguished from all other oligohymenophoreans by the presence of the adhesive disc, this character being a synapomorphy for the Mobilia.
Science China-life Sciences, 2020
Heterotrichous ciliates play an important role in aquatic ecosystem energy flow processes and many are model organisms for research in cytology, regenerative biology, and toxicology. In the present study, we combine both morphological and molecular data to infer phylogenetic relationships at family-genus level and propose new evolutionary hypotheses for the class Heterotrichea. The main results include: (1) 96 new ribosomal DNA sequences from 36 populations, representing eight families and 13 genera, including three poorly annotated genera, Folliculinopsis, Ampullofolliculina and Linostomella; (2) the earliest-branching families are Spirostomidae in single-gene trees and Peritromidae in the concatenated tree, but the family Peritromidae probably represents the basal lineage based on its possession of many "primitive" morphological characters; (3) some findings in molecular trees are not supported by morphological evidence, such as the family Blepharismidae is one of the most recent branches and the relationship between Fabreidae and Folliculinidae is very close; (4) the systematic positions of Condylostomatidae, Climacostomidae, and Gruberiidae remain uncertain based either on morphological or molecular data; and (5) the monophyly of each genus included in the present study is supported by the molecular phylogenetic trees, except for Blepharisma in the SSU rDNA tree and Folliculina in the ITS1-5.8S-ITS2 tree.
Progress in Natural Science, 2009
The phylogenetic relationship among tintinnid ciliates are relatively poorly studied based on molecular data. In the present work, seven species belonging to five genera of the order Tintinnida (Amphorellopsis acuta, Codonellopsis nipponica, Favella taraikaensis, Stenosemella nivalis, Tintinnopsis beroidea, Tintinnopsis cylindrica and Tintinnopsis lohmanni) were analyzed using the information on their small subunit ribosomal RNA gene sequences. Phylogenetic trees were constructed using Bayesian inference (BI), maximum parsimony (MP), neighbor-joining (NJ), and least-squares (LS) methods. Generally, similar topologies were revealed with high or moderate supports, in which the main results show that (1) all tintinnids analyzed belong to a single assemblage; (2) congeners in Tintinnopsis do not cluster together, which indicates that the lorica-based definition for this genus is not consistent with the SSU rRNA phylogeny;
European Journal of Protistology, 2001
The small subunit rRNA (SSrRNA) genes were sequenced for the hypotrichous ciliates, Aspidisca steini and Euplotes vannus. These two genera form a monophyletic clade and branch first in the euplotid clade at a long level with strong bootstrap support in both distance matrix and maximum parsimony tree construction methods. The phylogenetic trees further suggest the postulated relationships among families within the order Euplotida that (1) the order Euplotida, represented by Uronychia, Diophrys, Euplotidium, Euplotes and Aspidisca, forms a paraphyletic group; (2) the families Euplotidae and Aspidiscidae, likely as a monophyletic clade, share a common ancestor; (3) two other related genera, Uronychia and Diophrys, which were usually placed in the family Uronychiidae, branch later and share closer relationship each other than they are to other euplotids. On the contrary, Euplotidium arenarium, placed in the family Gastrocirrhidae, might be more closely related to Uronychia-Diophrys than to the Aspidisca-Euplotes group.
Journal of Eukaryotic Microbiology, 2004
ABSTRACT. We have used small subunit rRNA gene sequences to determine the phylogenetic relationships of species in three genera of endosymbiotic ciliates. We have confirmed that the astome Anoplophrya marylandensis is related to ciliates in the Class Oligohy-menophorea, supporting the view that astomes are derived from hymenostome-like ancestors. We confirmed that Plagiotoma lumbrici, formerly considered to be a heterotrich, is a stichotrich spirotrich ciliate most closely related to Paraurostyla weissei in this analysis. Thus, the somatic polykinetids of Plagiotoma can be concluded to be cirri. We report the details of our isolation of Nyctotheroides deslierresae and Nyctotheroides parvus and confirm previous reports that these clevelandellids are related to the metopid and caeno-morphid ciliates, now placed in the Class Armophorea.
Zoologica Scripta, 2012
We studied the morphology, morphometry, resting cysts, and molecular phylogeny of a new woodruffiid ciliate, Etoschophrya inornata, from ephemeral puddles and two lacustrine habitats in Idaho, Northwest U.S.A. Up to now the genus Etoschophrya has included a single species, E. oscillatoriophaga, from which our new form is distinguished by (1) the absence of interkinetal cortical granules and, consequently, the absence of extrusible red material in methyl green-pyronin stains; (2) usually ≥ five adoral membranelles vs. usually four; (3) greater length and length:width ratio; (4) prominent cortical furrows vs. inconspicuous; and (5) adaptation to nonsaline semiterrestrial and lacustrine habitats in the Nearctic vs. highly saline alkaline Afrotropic soil habitats. Resting cysts have two distinct membranes and a thick hyaline mucous pericyst layer. However, only one membrane persists in older cysts. Like its congener, E. inornata feeds exclusively on filamentous cyanobacteria. The 18S rRNA gene sequence places this species in a strongly supported clade with Kuklikophrya ougandae basal to the other platyophryids. We include a morphologic cladistic analysis of platyophryid ciliates and present a hypothetical scenario for the evolution of the platyophryid oral structures.