Peritrich Species Research Articles

Taxonomy and phylogeny of Pseudovorticella ciliates (Ciliophora, Peritrichia): Two new and one rare species from the coastal waters of China

Peritrich ciliates are a species-rich group of sessile unicellular eukaryotes, which can be found in various aquatic habitats from all over the world. It is well accepted that there are still many ciliates to be uncovered. During a survey on ciliate biodiversity in the coastal waters of China, three solitary peritrich species were identified as members of the genus Pseudovorticella Foissner & Schiffmann, 1975, including two new species and a rare one. Pseudovorticella zhejiangensis sp. n. differs from its congeners mainly by having a conical-shaped zooid, conspicuous pellicular blisters, one ventral and one dorsal contractile vacuoles, and an infundibular polykinety 3 with three rows of nearly equal length but different beginning positions. Pseudovorticella dalianensis sp. n. can be defined mainly by an obovoid-shaped zooid, one ventral contractile vacuole, and a three-rowed infundibular polykinety 3 with the middle row being the longest. The rare species, Pseudovorticella verrucosa (Dons, 1915) Sun et al., 2009, was redescribed. The small subunit (SSU) rDNA sequences of these three species were sequenced for the first time, the phylogeny of Pseudovorticella species was analyzed, and the results verified the non-monophyly of this genus. This study demonstrates that the morphologic and gene barcoding data are the optimum combination to disclose the biodiversity of ciliates.

A checklist of ciliates (Ciliophora) inhabiting on cnidarians.

A compilation of the ciliate epibiont species (Ciliophora) found on marine and fresh water cnidarians has been carried out based on published records. The checklist includes the taxonomic position of each species of epibiontic ciliate, the species of basibiont cnidarians, the geographic zones and the bibliographic references where they were recorded. Cnidarians, especially colonial sessile forms, represent suitable substrates for numerous sessile and vagile ciliates. Altogether 79 ciliate species belong to five classes viz. Spirotrichea, Heterotrichea, Phyllopharingea, Suctorea and Oligohymenophorea were listed. The most diverce as epibions on cnidarians are representatives of Suctorea with 41 species and Peritrichia (under the class Oligohymenophorea) with 25 species. Three species belong to class Spirotrichea, four Heterotrichea and one Phyllopharingea. Among the other representatives (except Peritrichia) of class Oligohymenophorea, four species belong to subclass Scutucociliatia, one species each in subclass Hymenostomatia and Apostomatia. One suctorian species Ophryodendron abietinum and two species of peritrichs, Cothurnia cordylophora and Rhabdostyla sertularium one Heterotrichea Halofolliculina corallasia and one Scutucociliatia Philaster guamensis are likely specific to cnidarian hosts only.

Effect of Cothurnia variabilis and Epistylis gammari (Ciliophora: Peritrichia) on Metabolic Rate of the Crayfish Cambarellus (Cambarellus) montezumae

Peritrichs usually settle on the external surface and gills of crustaceans. However, their physiological effect on the host has not been studied. Respiratory rate is a susceptible index for some factors that affect an organism. To test if ciliates attached to the crustacean gills have a physiological effect, we measured crustacean oxygen consumption in a closed system. Crayfish Cambarellus (Cambarellus) montezumae were collected in Lago Xochimilco in Mexico City and were isolated in chambers. Two peritrich species, Cothurnia variabilis (32.5%) and Epistylis gammari (67.5%), were observed on the gills. The metabolic rate was evaluated by oxygen consumption with a polarimetric oximeter. Statistical analyses demonstrated that a density of ciliates attached to the gills of the crayfish above ~50 individuals increased oxygen consumption with a positive correlation to epibiont density. We conclude that C. variabilis and E. gammari ciliate epibionts attached to the gill of the crayfish Cambarellus (Cambarellus) montezumae cause an increase in metabolic rate.

Functional Ecology of Two Contrasting Freshwater Ciliated Protists in Relation to Temperature.

We conducted microcosm experiments with two contrasting freshwater ciliates on functional traits (FTs) related to their growth rate (numerical response, NR) and ingestion rate (functional response, FR) over a range of ecologically relevant temperatures. Histiobalantium bodamicum and Vorticella natans are common planktonic ciliates but their abundance, swimming behavior, and temperature tolerance are different. In contrast to most sessile peritrich species, the motile V. natans is not strictly bacterivorous but also voraciously feeds upon small algae. We observed three main alterations in the shape of NR of both species with temperature, that is, change in the maximum growth rate, in the initial slope and in the threshold food level needed to sustain the population. Similarly, maximum ingestion rate, gross growth efficiency (GGE), and cell size varied with temperature and species. These findings caution against generalizing ciliate performance in relation to the ongoing global warming. Our results suggest that V. natans is the superior competitor to H. bodamicum in terms of temperature tolerance and bottom‐up control. However, the abundance of V. natans is usually low compared to H. bodamicum and other common freshwater ciliates, suggesting that V. natans is more strongly top‐down controlled via predation than H. bodamicum. The taxonomic position of V. natans has been debated. Therefore, to confirm species and genus affiliation of our study objects, we sequenced their small subunit ribosomal RNA (SSU rDNA) gene.

A checklist of ciliates (Ciliophora) inhabiting on ostracods (Crustacea, Ostracoda).

A compilation of the ciliated species found on freshwater and marine ostracods as epibiont or parasite (endobiont) has been carried out based on published records. The checklist includes the taxonomic position of each species of epibiontic and endobiontic ciliate, the species of basibiont ostracodes, the geographic zones and the bibliographic references where they were recorded. Altogether 7 suctorian, 29 peritrich, one apostome and one scuticociliatid species were listed. Two of recorded suctorian species are possible specific to marine ostracodes, whereas only one, Tokophrya sibirica to freshwater hosts. Fourteen species of peritrichs are likely specific to freshwater ostracodes, while three possible specific to marine ostracode hosts. Other suctorian and peritrich ciliate species were found on a variety of host taxa. One species of scuticociliatid was recorded as endobiont in ostracod.

Diversity and Distribution of Peritrich Ciliates on the Snail Physa acuta Draparnaud, 1805 (Gastropoda: Physidae) in a Eutrophic Lotic System.

Bianca Sartini, Roberto Marchesini, Sthefane D ´ávila, Marta D'Agosto, and Roberto Júnio Pedroso Dias (2018) Freshwater gastropods represent good models for the investigation of epibiotic relationships because their shells act as hard substrates, offering a range of microhabitats that peritrich ciliates can occupy. In the present study we analyzed the community composition and structure of peritrich epibionts on the basibiont freshwater gastropod Physa acuta. We also investigated the spatial distribution of these ciliates on the shells of the basibionts, assuming the premise that the shell is a topologically complex substrate. Among the 140 analyzed snails, 60.7% were colonized by peritrichs. We observed seven peritrich species: Epistylis plicatilis and Epistylis sp. (Epistylididae); Opercularia articulata (Operculariidae); Carchesium polypinum, Vorticella campanula and Vorticella sp. (Vorticellidae) and Thuricola kellicottiana (Vaginicollidae). We observed a high prevalence of epibiosis (> 60%) when all species of ciliates were considered conjunctly. However, the prevalence was low (1-58%) when each species was considered separately, reflecting their aggregate distribution pattern. The most prevalent species were Epistylis sp. (58.60%), Vorticella sp. (14.30%) and O. articulata (13.60%). Although the epibionts were distributed through the shell's entire extension, we observed greater values of abundance, density, diversity and dominance on the dorsal surface. Only Epistylis sp. was widely distributed on the ventral surface. We also observed that the peritrichs predominantly occupied the areas of the shell delimited by the sutures. We interpreted these distribution patterns considering that the peritrichs select their attachment sites under pressures related to basibiont behavior, physical forces that may dislocate them and protective characteristics of the shell's areas.

A checklist of epibiont suctorian and peritrich ciliates (Ciliophora) on halacarid and hydrachnid mites (Acari: Halacaridae Hydrachnidia).

Based on published records and original data, a list of the epibiont suctorian and peritrich ciliates (Ciliophora) on halacarid and hydrachnid mites is presented. Altogether 13 suctorian and 10 peritrich species from hydrachnid and halacarid mites were listed. From this list, six suctorian and one peritrich species have been reported from halacarid mites, while four suctorian and four peritrich species were found on hydrachnid mites determined up to species level. The remaining specimens were determined upto the generic level. The halacarid and hydrachnid species do not share any suctorian and peritrich species and some of the ciliate species are specific to certain taxonomic groups of the hosts.The host specificity of both suctorian and peritrich ciliates, localization on the host body and environment are discussed. Some ciliate species specific to hydrachnid mites prefer lotic or lentic habitats. In most cases, both suctorian and peritrich ciliates prefer only marine or only fresh water bodies. It was also mentioned that both suctorian and peritrich ciliates have not distinct preferences in localization on their host body.

Development and evaluation of specific PCR primers targeting the ribosomal DNA-internal transcribed spacer (ITS) region of peritrich ciliates in environmental samples

Peritrich ciliates are highly diverse and can be important bacterial grazers in aquatic ecosystems. Morphological identifications of peritrich species and assemblages in the environment are time-consuming and expertise-demanding. In this study, two peritrich-specific PCR primers were newly designed to amplify a fragment including the internal transcribed spacer (ITS) region of ribosomal rDNA from environmental samples. The primers showed high specificity in silico, and in tests with peritrich isolates and environmental DNA. Application of these primers in clone library construction and sequencing yielded exclusively sequences of peritrichs for water and sediment samples. We also found the ITS1, ITS2, ITS, D1 region of 28S rDNA, and ITS+D1 region co-varied with, and generally more variable than, the V9 region of 18S rDNA in peritrichs. The newly designed specific primers thus provide additional tools to study the molecular diversity, community composition, and phylogeography of these ecologically important protists in different systems.

Phylogenomics solves a long-standing evolutionary puzzle in the ciliate world: The subclass Peritrichia is monophyletic

The phylum Ciliophora is one of the most broadly studied protozoan lineages. The era of molecular investigation has brought forth a major ongoing debate: is the subclass Peritrichia Stein, 1859 monophyletic? Numerous analyses mostly using the small subunit (SSU) rRNA gene have failed to recover the Mobilida and Sessilida, the two peritrich orders, as sister clades. Here we have sequenced five peritrich species - three sessilids and two mobilids. We constructed a supermatrix of 158 genes and 44,696 characters for 24 ciliate species, and as outgroup taxa, nine species from the Apicomplexa and four from the Dinophyceae. Our analyses using both maximum likelihood and Bayesian methods recover a monophyletic class Oligohymenophorea and two robust clades within it. The first clade is a monophyletic Peritrichia with the orders Sessilida and Mobilida maximally supported as sister clades. The second oligohymenophorean clade includes species of the subclasses Scuticociliatia and Hymenostomatia, which are sister clades. Our analyses resolve a long-standing debate in ciliate molecular phylogenetics and provide support for the classical view that the morphological features of the two peritrich orders Mobilida and Sessilida arose by descent from the same common ancestor and are not the result of convergence.

Description of Epistylis camprubii n. sp., a Species Highly Tolerant to Ammonium and Nitrite

A new peritrich species highly tolerant to ammonium and nitrite, Epistylis camprubii n. sp., was found adhered to the biofilm of two advanced wastewater treatment plants treating high ammonium-loaded wastewater in Rubi, Spain. Its morphology, oral infraciliature and phylogenetic position in the peritrich clade were studied. The new species is a vase-shaped peritrich, constricted below the peristomial lip, with an in vivo average length of 58.7 ± 10.1 µm, average width of 32.0 ± 5.4 µm, and a longitudinally striated, compact stalk that occasionally exhibits uneven thickness and rarely shows transverse segments. The peristomial disc is commonly rounded or pointed, and rarely umbilicated. The C-shaped macronucleus is located in the adoral half of the body, and the only contractile vacuole lies in the adoral third of the zooid. The molecular analysis of the 18s gene sequence clustered E. camprubii n. sp. together with the other Epistylis, with the exception of Epistylis galea.

Epibiosis and hyperepibiosis onPagurus bernhardus(Crustacea: Decapoda) from the west Coast of Scotland

The presence of a diverse range of epibionts was found onPagurus bernhardusfrom the west coast of Scotland. The invertebrate species found on the shell inhabited by the crab were the hydrozoansHydractinia echinataandDycorine conferta, the cirripedsBalanus balanusandBalanus crenatus, the polychaetesHydroides norvegica,Pomatoceros triqueterandCirceis armoricana, and the molluscsHiatella arcticaandAnomia ephippium. On the crab were observed the polychaeteCirceis armoricanaand the amphipodPodoceropsis nitida. In addition, on the gastropod shells occupied byP. bernhardus, ciliate protozoan species were found attached to the hydrozoanDycorine conferta, this being hyperepibiosis. These ciliates were 6 suctorian (Conchacineta constricta,Corynophrya anisostyla,Actinocyathula homari,Actinocyathula crenata,Acineta sulcataandAcineta corophii), and one peritrich species (Zoothamniumsp.). This is the first time that this hyperepibiosis was observed. In contrast to the epibiont communities observed in previous surveys in the same sampling area, basibiont specimens withoutD. confertadid not show ciliate epibionts. The ciliate epibionts also were not present on the surface of the shell and crab in specimens withD. conferta; they only appeared in hyperepibiosis on the surface of the hydrozoan. The spatial distribution and abundance of the invertebrate epibiont species were analysed, as well as the morphology, taxonomy and distribution of the ciliate hyperepibionts.

Redescriptions of five species of marine peritrichs, Zoothamnium plumula, Zoothamnium nii, Zoothamnium wang, Pseudovorticella bidulphiae, and Pseudovorticella marina (Protista, Ciliophora)

The significant similarity of congeners and an accumulation of inaccurate descriptions or misinterpretations in previous studies can make it difficult to separate species of peritrich ciliates from one another. Isolates collected from Chinese coastal waters allowed investigation and redescription of three marine species of peritrichs, Zoothamnium plumula Kahl, 1933, Z. nii Ji et al., 2005 and Z. wangi Ji et al., 2005, emphasizing in particular details of characters observed in vivo, infraciliature and comparisons with morphologically similar congeners. Brief redescriptions based on new material also are provided for two other marine peritrichs, Pseudovorticella bidulphiae (Stiller, 1939) Ji et al., 2009 and P. marina (Greeff, 1870) Ji et al., 2009.

A new interpretation of stomatogenesis in a peritrich ciliate: Using Campanella umbellaria as a model system

The process of stomatogenesis in peritrich ciliates is still incompletely understood. Previous studies on the stomatogenesis of four species of peritrichs, Telotrochidium sp., Carchesium polypinum, Opercularia coarctata, and Astylozoon pyriforme conflict with one another in some cases and omit details of events in others. We described the entire process of stomatogenesis in the peritrich ciliate Campanella umbellaria (C. umbellaria) using an improved method of staining with protargol. Our results disagree with some previous studies with regard to the formation of some rudimentary structures, reorganization of the parental haplokinety, formation of new germinal rows, and separation of daughter oral complexes. The pattern of stomatogenesis characteristic of peritrichs is compared to the stomatogenetic patterns of three other oligohymenophorean subclasses and a hypothesis about the evolution of stomatogenesis in the class Oligohymenophorea is offered. Details of stomatogenesis need to be described and verified in a greater variety of peritrichs to clarify possible differences between taxa and make it possible to relate stomatogenesis to evolution within the subclass Peritrichia. Ultrastructural studies are the next step in description of morphogenetic processes in peritrichs, and characteristics of C. umbellaria make it a useful model for this work.

Morphological Characterization and Intraspecific Variation of Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) Attached to Calanoid Copepods in the Chesapeake Bay, USA

A redescription of Zoothamnium intermedium Precht, 1935, a peritrich epibiont on copepods, is provided using specimens colonizing Acartia tonsa and Eurytemora affinis in Chesapeake Bay, USA. Bell-shaped zooids of Z. intermedium ranged in size from 31.2-54.7 microm x 16.7-31.3 microm in vivo. A single contractile vacuole and a "C shaped" macronucleus lie in the upper half of the body. Colonies had up to 30 zooids, but most presented two to four zooids. The single myoneme was continuous from the zooids through the lateral branches and basal stalk, terminating 4-73.2 mm before the attachment point of the colony. The ciliature of Z. intermedium was typical of sessile peritrichs, consisting of an outer haplokinety and an inner polykinety 1 (PK1) that made approximately turns around the peristomial disk before entering the infundibulum. Within the infundibulum, PK 1 was accompanied by polykinetid 2 (PK2) and polykinetid 3 (PK3), each consisting of three kinetosomal rows: PK2 of Z. intermedium terminated adoral to the aboral end of PK1 and had a central row of kinetosomes shorter than the lateral rows. Scanning electron microscopy revealed an annular pattern of pellicular ridges with pellicular pores. Morphological features used in peritrich species identification are quantified for specimens attached to both hosts and compared with other species of Zoothamnium. Statistically significant differences found between specimens attached to A. tonsa and E. affinis may reflect phenotypic plasticity rather than infestation by multiple species of Zoothamnium.

Redescription of four species of lagenophryid peritrichs (Ciliophora) from Australia and New Guinea, with descriptions of two new species

Four insufficiently described species of ectosymbiotic peritrich ciliates in the family Lagenophryidae that occur on crustacean hosts in Australia and New Guinea are redescribed. These include two species of Operculigera from phreatoicid isopods, one species of Setonophrys from a phreatoicid isopod, and one species of Lagenophrys from a palaemonid shrimp. Two undescribed species of Operculigera, also found on phreatoicid isopods, are described for the first time. Australian species of Operculigera appear to be restricted to phreatoicid hosts. This is unusual because a diverse array of other lagenophryids occur on parastacid crayfish in Australia. Furthermore, species of Operculigera are conspicuous symbionts of parastacids and various freshwater crabs in Chile and Madagascar. In addition to this peculiarity of distribution, the Australian species of Operculigera appear to comprise a morphologically distinct group within the genus.

A New Noncanonical Nuclear Genetic Code: Translation of UAA into Glutamate

Deviant genetic codes reported in ciliates share the same feature: one (UGA) or two (UAR) of the three canonical stop codons are translated into one particular amino acid. In many genera, such as Oxytricha, Paramecium, and Tetrahymena, UAR codons are translated into glutamine. UGA is translated into cysteine in Euplotes or into tryptophan in Colpoda inflata and Blepharisma americanum. Here, we show that three peritrich species (Vorticella microstoma, Opisthonecta henneguyi, and Opisthonecta matiensis) translate UAA into glutamate and that at least UAA in O. matiensis is decoded through a mutant suppressor-like tRNA. This kind of genetic code has never been reported for any living organism. Phylogenetic analysis with α-tubulin sequences corroborates that peritrichs, peniculines (Paramecium), and hymenostomates (Tetrahymena) form a monophyletic group (class Oligohymenophorea). The differential translation (glu/gln) of UAR codons, the monophyly of the Oligohymenophorea, and the common evolutionary origin of glutamate and glutamine suggest that deviant genetic codes of present-day oligohymenophoreans could have the same origin.

Epibionts of Asellus aquaticus(L.) (Crustacea, Isopoda): an SEM study

1. This study presents a qualitative and quantitative survey of epibionts infesting two populations of the freshwater isopod Asellus aquaticus (L.). Using scanning electron microscopy, the prevalence, mean intensity, abundance, spatial preferences and distribution of organisms on various external surfaces were ascertained.2. A diverse community, consisting primarily of protozoa and rotifers, utilised A. aquaticus as a substrate organism. Every individual A. aquaticus supported some form of epizoic life. Peritrich species comprised 89.2% of all epibionts. Carchesium polypinum, Pseudocarchesium aselli, Pseudocarchesium asellicola, Pseudocarchesium simulans and Opercularia hebes dominated the epifauna.3. Highest epibiont burdens occurred on the mouthparts, the first few ventral segments and the gills and largely comprised the above peritrich species. Most epibionts exhibited some degree of site preference on the host. A distinct gill epifauna existed. Apart from Acineta tuberosa and Vorticella rotunda, which had equal prevalences on dorsal and ventral surfaces in one culture, most species largely avoided the dorsal surface.4. Epibionts exhibited varying degrees of adaptation to life on a living substrate. They ranged from facultative species such as A. tuberosa, which are capable of colonising abiotic substrata, to Gymnodinoides aselli whose life cycle relies on interaction with A. aquaticus. Highly specialised species tended to exhibit the most pronounced and consistent site restriction.5. Asellus aquaticus offers a highly tractable system for further study of substrate species–epibiont relationships.

A new genus and two new species of marine peritrichous ciliates (Protozoa, Ciliophora, Peritrichida) from Qingdao, China

Abstract This paper deals with descriptions of a new genus and two new species of marine peritrichs, Pseudovorticella longa nov. spec. and Zoothamnopsis mengi nov. gen., nov. spec. Both organisms were collected from eutrophic waters (mollusca-breeding and shrimp-farming ponds) off the coast of Qingdao, China. Their morphology, infraciliature and silverline system were studied and investigated from living and silver-stained organisms. The new genus Zoothamnopsis has all the characteristics of the well-known genus Zoothamnium but with a reticulate silverline system like that of Pseudovorticella. Zoothamnopsis mengi nov. spec. is a medium-sized form with dichotomously branched stalk and one apically located contractile vacuole; C-shaped macronucleus is horizontally located; zooids in vivo are about 50–70 × 20–30 μm. Number of silverlines: from oral area to aboral ciliary wreath ca. 76–87; AbW to scopula 30–36. The new species Pseudovorticella longa measures 30–45 × 15–25 μm and is unique by having a dorsally located contractile vacuole, smooth cell surface and very fine pellicular striations, asymmetrical elongated body shape and a long, strongly twisted macronucleus. Number of silverlines: from oral area to aboral ciliary wreath: 42–47; AbW to scopula: 10–12.

Revision of the Family Lagenophryidae Bütschli, 1889 and Description of the Family Usconophryidae N. Fam. (Ciliophora, Peritricha)1

Ten species of lagenophryid peritrichs in three genera are redescribed or described for the first time. Based on this information, the family Lagenophryidae was found to consist of five genera: Lagenophrys, Paralagenophrys, Clistolagenophrys n. g., Setonophrys, and Operculigera. Lagenophryid genera differ in gross structure of the lorica aperture and the peristomial sphincter associated with it. Shape of the lorica and mode of attachment to the host are not generic characteristics in the Lagenophryidae. Differences in shape evolved within each of the three largest lagenophryid genera merely as adaptations for attachment to different parts of a host. Usconophrys, formerly in the Lagenophryidae, and Cyclodonta are assigned to the family Usconophryidae n. fam., which is characterized by possession of a lorica, lack of a closure apparatus operated by the peristomial sphincter, and possession of an operculariform peristome. Lagenophrys, Setonophrys, and Paralagenophrys appear to have evolved separately and convergently from ancestors within Operculigera. Lagenophryid lorica apertures consisting of opposing lips probably evolved as tight seals to prevent water loss when the host is temporarily out of water. The greater diversity and wider distribution of Lagenophrys compared with other lagenophryid genera may result from an advantage in recolonizing hosts conferred by second-type division.

Notes on the morphology and asexual reproductive processes of sessile peritrichs

The morphology and asexual reproductive processes of two sessile peritrich species were studied, i.e. Epistylis anastatica Linnaeus, 1767 and Vorticella convallaria Linnaeus, 1758. Taxonomic descriptions of the two organisms are given and the processes of telotroch formation and binary fission are described. Photographic records of the reproductive processes in the living organisms are presented. Prominent differences were observed between the asexual reproductive processes of the two organisms. These differences were manifested in the sequence of events, duration of processes and morphology and formation of telotrochs. It is suggested that processes of reproduction could be of taxonomic significance within this group of organisms.