Search

Thomas Cavalier‐Smith, born in London, U.K., on October 21, 1942, was a Professor of Evolutionary Biology in the Department of Zoology at the University of Oxford at the time of his death on March 19, 2021. Credited with at least 235 research works and over 20,000 citations, Cavalier‐Smith was a well‐known and widely respected scientist who took a bold and detailed approach to understanding major transitions in evolution, including the role of endosymbiosis. He was noted for his willingness to question theories and constantly accumulate and evaluate data, motivated by science for the sake of science. This paper reviews Thomas Cavalier‐Smith's major accomplishments, examines his theoretical approaches, and provides highlights from the "Tree of Life Symposium" sponsored by the International Society of Protistologists (ISOP) and the International Society of Evolutionary Protistology (ISEP) on June 21, 2021, to celebrate Tom's life and work. [ABSTRACT FROM AUTHOR]

In recent years, Tetrahymena species have been used as model organisms for research in a wide range of fields, highlighting the need for a fuller understanding of the taxonomy of this group. It is in this context that this paper uses living observation and silver staining methods to investigate the morphology and infraciliature of one Tetrahymena species, T. setosa (Schewiakoff 1892 Verh. Naturh. Med. Ver. Heidelb., 4:544) McCoy (1975) Acta Protozool., 14:253; the senior subjective synonym of T. setifera Holz and Corliss (1956) J. Protozool., 3:112; isolated from a freshwater pond in Harbin, north-eastern China. This organism can be distinguished from other described Tetrahymena species mainly by its single caudal cilium, which is about twice the length of the somatic ciliature. While the Harbin isolate appears similar to the population described by Holz and Corliss (1956) J. Protozool., 3:112, an improved diagnosis for T. setosa is given based on the previous descriptions and the Harbin population. In summary, this species can be recognized mainly by the combination of the following characters: body in vivo approximately 40 μm × 25 μm, 21-26 somatic kineties, one to four contractile vacuole pores associated with meridians 6-11 and a single caudal cilium. The small subunit ribosomal (SSU) rRNA gene and the cox1 gene sequences of Harbin population are also characterized in order to corroborate that the isolated species branches in phylogenetic trees as a T. setosa species. The phylogenetic analysis also indicated that sequences of populations of Tetrahymena species should be published with detailed morphological identifications., (© 2018 International Society of Protistologists.)

The traditional green algal genus Chloromonas accommodates mesophilic, cold-tolerant and cold-adapted microorganisms. In this paper, we studied a new strain isolated from a wet hummock meadow in the High Arctic. We used morphological, ultrastructural and molecular data to assess the taxonomic position and phylogenetic relationships of the new isolate. The observed morphological features generally corresponded to the cold-tolerant Chloromonas characteristics. However, ellipsoidal or wide ellipsoidal vegetative cells, a massive parietal cup-shaped chloroplast with a number of continuously connected lobes, a thick cell wall, a prominent hemispherical papilla and the anterior position of an oblong or round eyespot distinguished the alga from all previously described Chloromonas species. Analyses of rbcL and 18S rRNA genes showed that the new strain formed an independent lineage within a clade containing mesophilic and psychrotolerant Chloromonas species. Comparisons of secondary structure models of a highly variable ITS2 rDNA marker supported a separate species identity of the new isolate. Considering the morphological and molecular differences from its relatives, a new psychrotolerant species, Chloromonas svalbardensis, is proposed. Further, our results demonstrated the paraphyletic origin of Chloromonas within Chloromonadinia with genetically, morphologically and ecologically well-defined clades. We discuss a scenario of a possible Chloromonas split and revision., (© 2018 International Society of Protistologists.)

The morphology of Nyctotheroides hubeiensis (Acta Hydrobiol. Sin. 1998, 22(suppl.):187), collected from the rectum of Phelophylax nigromaculatus, is presented in this paper based on detailed morphological information and molecular data. Our phylogenetic analysis showed that N. hubeiensis fell into the Nyctotheroides clade, which was strongly supported as monophyletic and clustered as basal to the genera Nyctotherus and Clevelandella. Also, the monophyly of the Order Clevelandellida and the affinity of parasitic nyctotherids and free-living metopids were indicated in our work. The origin of clevelandellid ciliates as well as their possible evolutionary history was also discussed here; however, the analysis of more species from other vertebrate hosts (fish, reptiles) should be made before a well-supported conclusion can be drawn., (© 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.)

Three peritrichous ciliates, Zoothamnium arcuatum n. sp., Z. grossi n. sp., and Z. parahentscheli Sun et al., 2009, were collected from an estuary of the Taehwagang River, Korea. All these species were investigated based on live observations and silver staining, and their small subunit (SSU) rRNA gene was also sequenced. Zoothamnium arcuatum can be identified by a goblet-shaped colony, double-layered peristomial lip, and abstomally shortened row 3 of infundibular polykinety 3 (P3). Zoothamnium grossi is morphologically characterized by an alternately branched stalk with the lowest secondary stalk diverging from the main part of colony, asymmetrically bell-shaped zooids, and three short, parallel ciliary rows in P3. Phylogenetic analysis revealed that the three Zoothamnium species described in this paper clustered with other members of the family Zoothamniidae, as expected., (© 2015 The Author(s) Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.)

Euglenids are a diverse group of flagellates that inhabit most environments and exhibit many different nutritional modes. The most prominent euglenids are phototrophs, but phagotrophs constitute the majority of phylogenetic diversity of euglenids. They are pivotal to our understanding of euglenid evolution, yet we are only starting to understand relationships amongst phagotrophs, with the backbone of the tree being most elusive. Ploeotids make up most of this backbone diversity—yet despite their morphological similarities, SSU rDNA analyses and multigene analyses show that they are non‐monophyletic. As more ploeotid diversity is sampled, known taxa have coalesced into some subgroups (e.g. Alistosa), but the relationships amongst these are not always supported and some taxa remain unsampled for multigene phylogenetics. Here, we used light microscopy and single‐cell transcriptomics to characterize five ploeotid euglenids and place them into a multigene phylogenetic framework. Our analyses place Decastava in Alistosa; while Hemiolia branches with Liburna, establishing the novel clade Karavia. We describe Hemiolia limna, a freshwater‐dwelling species in an otherwise marine clade. Intriguingly, two undescribed ploeotids are found to occupy pivotal positions in the tree: Chelandium granulatum nov. gen. nov. sp. branches as sister to Olkasia, and Gaulosia striata nov. gen. nov. sp. remains an orphan taxon. [ABSTRACT FROM AUTHOR]

Species of Acanthamoeba were first described using morphological characters including cyst structure and cytology of nuclear division. More than 20 nominal species were proposed using these methods. Morphology, especially cyst shape and size, has proven to be plastic and dependent upon culture conditions. The DNA sequence of the nuclear small-subunit (18S) rRNA, the Rns gene, has become the most widely accepted method for rapid diagnosis and classification of Acanthamoeba. The Byers-Fuerst lab first proposed an Rns typing system in 1996. Subsequent refinements, with an increasing DNA database and analysis of diagnostic fragments within the gene, have become widely accepted by the Acanthamoeba research community. The development of the typing system, including its current state of implementation is illustrated by three cases: (i) the division between sequence types T13 and T16; (ii) the diversity within sequence supertype T2/T6, and (iii) verification of a new sequence type, designated T20. Molecular studies make clear the disconnection between phylogenetic relatedness and species names, as applied for the genus Acanthamoeba. Future reconciliation of genetic types with species names must become a priority, but the possible shortcomings of the use of a single gene when reconstructing the evolutionary history of the acanthamoebidae must also be resolved. [ABSTRACT FROM AUTHOR]

This study reports the first record of Sorosphaerula radicalis (Phytomyxea, Rhizaria) in continental Europe (Tirol, Austria) and provides first molecular data for this species. An 18S rRNA phylogeny placed S. radicalis into the Plasmodiophorida, although distant from other members of the genus Sorosphaerula and close to the parasite of water cress Hillenburgia nasturtii. To resolve this polyphyly, we compare morphological data and life cycles of Sorosphaerula veronicae (the type species of the genus Sorosphaerula), Hillenburgia nasturtii, and Sorosphaerula radicalis. We conclude that Sorosphaerula radicalis belongs to the recently established genus Hillenburgia. [ABSTRACT FROM AUTHOR]

Protists in the phylum Ciliophora possess a complex membrane‐trafficking system, including osmoregulatory Contractile Vacuoles and specialized secretory organelles. Molecular cell biological investigations in Tetrahymena thermophila have identified components of the protein machinery associated with the secretory organelles, mucocysts. The Qa‐SNARE Syn7lp plays a role in mucocyst biogenesis as do subunits of the CORVET tethering complex (specifically Vps8). Indeed, Tetrahymena thermophila possesses expanded gene complements of several CORVET components, including Vps33 which is also a Sec1/Munc18 (SM) protein that binds Qa‐SNAREs. Moreover, the Qa‐SNAREs in Paramecium tetraurelia have been localized to various endomembrane organelles. Here, we use comparative genomics and phylogenetics to determine the evolutionary history of the SM and Qa‐SNARE proteins across the Ciliophora. We identify that the last ciliate common ancestor possessed the four SM proteins and six Qa‐SNAREs common to eukaryotes, including the uncommonly retained Syntaxin 17. We furthermore identify independent expansion of these protein families in several ciliate classes, including concurrent expansions of the SM protein‐Qa SNARE partners Sec1:SynPM in the oligohymenophorean ciliates lineage, consistent with novel Contractile Vacuole specific innovations. Overall, these data are consistent with SM proteins and Qa‐SNAREs being a common set of components for endomembrane modulation in the ciliates. [ABSTRACT FROM AUTHOR]

A recent ultrastructural study on the tintinnid ciliate Schmidingerella meunieri displayed unique types of somatic kinetids. The dikinetids (paired basal bodies) have, besides kinetodesmal fibrils and transverse ribbons, some special features, that is, overlapping postciliary ribbons and three extraordinary microtubular ribbons, which together form a conspicuous network in the ciliated anterior cell portion. The distribution of this feature among tintinnids is studied in chemically fixed and ultrathin‐sectioned specimens from six genera and five families collected in European coastal waters. The taxa are scattered across the molecular tree. Actually, the somatic kinetids of these six genera share the special features discovered in S. meunieri. Accordingly, the overlapping postciliary ribbons and the three extraordinary ribbons were already present in the early stages of tintinnid evolution, namely in the last common ancestor of tintinnids with hard loricae. Owing to the lack of ultrastructural data in the basally branching Tintinnidiidae with their soft loricae and in aloricate choreotrichids other than the aberrant strobilidiids, the first appearance of the structures is still uncertain. The related oligotrichids do not possess overlapping postciliary ribbons, but show electron‐dense material at the sites where the ribbons I–III originate in tintinnids. None of these features is found in any other spirotrich ciliate. [ABSTRACT FROM AUTHOR]

A novel genus and species within the order Glissmonadida (Cercozoa, Rhizaria), Saccharomycomorphapsychra n. g., n. sp., is described from lichen in the Ny‐Ålesund region (High Arctic) and moss in the Fildes peninsula of King George Island (Maritime Antarctica). Cells were spherical and did not appear to present flagella in organic‐rich Potato Dextrose Agar medium where they were able to feed osmotrophically. Molecular phylogenetic analyses based on 18S rRNA gene sequence demonstrated that Saccharomycomorphapsychra belong to "clade T" within the order Glissmonadida (Cercozoa, Rhizaria). All three investigated strains could grow at 4 °C and had an optimum growth temperature of 12 °C, 20 °C, and 20 °C, while a maximum growth temperature of 20 °C, 20 °C, and 25 °C, respectively. In conclusion, we established the phenotypic identity of "clade T," which until now was exclusively detected by environmental sequences, and erect a new family Saccharomycomorphidae for "clade T." Nomenclatural, morphological and ecological aspects of this novel species are discussed. [ABSTRACT FROM AUTHOR]

The morphology, morphogenesis and molecular phylogeny of Parabistichelladieckmanni (Foissner, 1998) Foissner, 2016, isolated from north China, were investigated. The Chinese population was characterized as having five to seven frontal cirri in corona, four to seven buccal cirri arranged in a row, two to four short frontal rows and two long frontoventral rows, three to seven transverse cirri, four macronuclear nodules, three dorsal kineties following a Gonostomum‐pattern, and caudal cirri absent. Morphogenetic research reveals that the main characteristics during binary fission are as follows: (1) the long left frontoventral row is formed by two or three anlagen; (2) the posterior part of the parental adoral zone of membranelles is renewed, and the oral primordium of the opisthe is formed intrakinetally; (3) FVT‐anlagen I to VI (or V, VII) produce each a frontal cirrus to form the frontal corona; (4) development of dorsal kineties follows the Gonostomum‐pattern. Phylogenetic analyses showed that P. dieckmanni does not group with other Parabistichella species. Therefore, the genus Parabistichella is polyphyletic. Additionally, Parabistichellavariabilis n. comb. (basionym: Bistichellavariabilis He & Xu, 2011) and Parabistichellacheni n. nom. (basionym: Parabistichellavariabilis Jiang et al., 2013) were suggested. [ABSTRACT FROM AUTHOR]

Symbioses between sponges and photosynthetic organisms are very diverse regarding the taxonomy and biogeography of both hosts and symbionts; to date, most research has focused on the exploration of bacterial diversity. The present study aims to characterize the culturable diversity of photosynthetic eukaryotes associated with sponges in the Aegean Sea, on which no information exists. Five microalgae strains were isolated from marine sponges; the strains were characterized by morphological features, and the 18S rRNA, 18S‐28S Internal Transcribed Spacer, and ribulose‐bisphosphate carboxylase large chain (rbcL) sequences. Our polyphasic approach showed that the strains belonged to the green‐alga Acrochaete leptochaete, the diatom Nanofrustulum cf. shiloi, the rhodophyte Acrochaetium spongicola, and the chlorachniophyte Lotharella oceanica. A. leptochaete is reported for the first time in sponges, even though green algae are known to be associated with sponges. Nanofrustulum shiloi was found in association with the sponges Agelas oroides and Chondrilla nucula, whereas information existed only for its association with the species Aplysina aerophoba. Acrochaetium spongicola was found for the first time in association with sponges in the eastern Mediterranean. Moreover, we report herein for the first time a sponge–chlorarachniophycean association. Our research revealed new diversity of microalgae associated with sponges and added new records of sponge species, previously unknown for their association with microalgae. [ABSTRACT FROM AUTHOR]

Myxomycetes (also called Myxogastria or colloquially, slime molds) are worldwide occurring soil amoeboflagellates. Among Amoebozoa, they have the notable characteristic to form, during their life cycle, macroscopic fruiting bodies, that will ultimately release spores. Some 1,000 species have been described, based on the macroscopic and microscopic characteristics of their fruiting bodies. We were interested in Physarum pusillum (Berk. & M.A. Curtis) G. Lister, a very common species described with two variants, each bearing such morphological differences that they could represent two distinct species. In order to test this, we observed key characters in a large selection of specimens attributed to P. pusillum, to its synonyms (in particular Physarum gravidum), and to related species. In addition, the small‐subunit ribosomal RNA gene was obtained from seven of these specimens. Based on these data, we provide a comprehensive phylogeny of the order Physarida (Eukaryota: Amoebozoa: Conosa: Macromycetozoa: Fuscisporidia). Morphology and phylogeny together support the reinstatement of P. gravidum Morgan 1896 with a neotype here designated, distinct from P. pusillum, here redefined. [ABSTRACT FROM AUTHOR]

Pleurostomatida Schewiakoff, 1896 is a cosmopolitan order of ciliates. In the present study, we investigated two new pleurostomatid species, Apolitonotus lynni gen. et sp. nov. and Protolitonotus clampi sp. nov., with state‐of‐the‐art methods. Apolitonotus lynni lacks its oral extrusomes and its right kineties form an anterior semi‐suture near the dorsal margin. Based on these two features, the new genus Apolitonotus was established within the Protolitonotidae Wu et al., 2017. Protolitonotus clampi differs from its congeners by its size of 80–130 × 15–30 μm, 4–6 left, and 9–11 right kineties, extrusomes arranged along the oral slit, and two macronuclear nodules. Because Litonotus antarcticus possesses an anterior semi‐suture and oral extrusomes, it was transferred to the genus Protolitonotus, becoming P. antarctius comb. nov. (basionym Litonotus antarcticus Song and Wilbert, 2002). Phylogenetic analyses based on SSU rDNA sequences suggest a sister group relationship of P. clampi and the family Kentrophyllidae, and A. lynni is adelphotaxon to Litonotus gracilis, both within the order Pleurostomatida. Based on the new findings, an improved diagnosis for Protolitonotus was also provided. [ABSTRACT FROM AUTHOR]

Holomastigotes is a protist genus (Parabasalia: Spirotrichonymphea) that resides in the hindguts of "lower" termites. It can be distinguished from other parabasalids by spiral flagellar bands that run along the entire length of the cell, an anterior nucleus, a reduced or absent axostyle, the presence of spherical vesicles inside the cells, and the absence of ingested wood particles. Eight species have been described based on their morphology so far, although no molecular data were available prior to this study. We determined the 18S rRNA gene sequences of Holomastigotes from the hindguts of Hodotermopsis sjostedti, Reticulitermes flavipes, Reticulitermes lucifugus, and Reticulitermes tibialis. Phylogenetic analyses placed all sequences in an exclusive and well‐supported clade with the type species, Holomastigotes elongatum from R. lucifugus. However, the phylogenetic position of Holomastigotes within the Spirotrichonymphea was not resolved. We describe two new species, Holomastigotes flavipes n. sp. and Holomastigotes tibialis n. sp., inhabiting the hindguts of R. flavipes and R. tibialis, respectively. [ABSTRACT FROM AUTHOR]

Environmental sequences have become a major source of information. High‐throughput sequencing (HTS) surveys have been used to infer biogeographic patterns and distribution of broad taxa of protists. This approach is, however, more questionable for addressing low‐rank (less inclusive) taxa such as species and genera, because of the increased chance of errors in identification due to blurry taxonomic boundaries, low sequence divergence, or sequencing errors. The specious ciliate genus Euplotes partially escapes these limitations. It is a ubiquitous, monophyletic taxon, clearly differentiated from related genera, and with a relatively well‐developed internal systematics. It has also been the focus of several ecological studies. We present an update on Euplotes biogeography, taking into consideration for the first time environmental sequences, both traditional (Sanger) and HTS. We inferred a comprehensive small subunit rRNA gene phylogeny of the genus including a newly described marine species, Euplotes enigma, characterized by a unique question mark‐shaped macronucleus. We then added available environmental sequences to the tree, mapping associated metadata. The resulting scenario conflicts on many accounts with previously held views, suggesting, for example, that a large diversity of anaerobic Euplotes species exist, and that marine representatives of mainly freshwater lineages (and vice‐versa) might be more common than previously thought. [ABSTRACT FROM AUTHOR]

Four new species of Vorticella, V. parachiangi sp. n., V. scapiformis sp. n., V. sphaeroidalis sp. n., and V. paralima sp. n., were isolated from coastal brackish waters of southern China. Their morphology, infraciliature, and silverline system were investigated based on observations of specimens both in vivo and following silver staining. Vorticella parachiangi sp. n. is distinguished by: a J‐shaped macronucleus; a single dorsally located contractile vacuole; a two‐rowed infundibular polykinetid 3, in which row 1 is shorter than row 2; 21–31 silverlines between peristome and aboral trochal band, 6–11 between aboral trochal band and scopula. Vorticella scapiformis sp. n. is characterized by its conspicuously thin and irregularly edged peristomial lip; a J‐shaped macronucleus; a single, ventrally located contractile vacuole; row 1 of the infundibular polykinetid 3 proximally shortened; 18–25 silverlines between peristome and aboral trochal band, 8–12 between aboral trochal band and scopula. Vorticella sphaeroidalis sp. n. can be identified by its small, sub‐spherical zooid; a C‐shaped macronucleus; a ventrally located contractile vacuole; an aboral trochal band adjacent to the scopula; 16–18 silverlines between persitome and aboral trochal band, two between aboral trochal band and scopula. Vorticella paralima sp. n. can be identified by its ovoidal zooid; a J‐shaped macronucleus; a dorsally positioned contractile vacuole; rows 1 and 2 of the infundibular polykinetid 3 proximally shortened; 26–35 silverlines from peristome to aboral trochal band, and 7–13 from aboral trochal band to scopula. The SSU rDNA genes of these four species were sequenced and their phylogeny was analyzed. [ABSTRACT FROM AUTHOR]

Tetrahymena mitochondrial cox1 barcodes and nuclear SSUrRNA sequences are particularly effective at distinguishing among its many cryptic species. In a project to learn more about Tetrahymena natural history, the majority of >1,000 Tetrahymena‐like fresh water isolates were assigned to established Tetrahymena species with the remaining assigned to 37 new species of Tetrahymena, nine new species of Dexiostoma and 12 new species of Glaucoma. Phylogenetically, all but three Tetrahymena species belong to the well‐established "australis" or "borealis" clades; the minority forms a divergent "paravorax" clade. Most Tetrahymena species are micronucleate, but others are exclusively amicronucleate. The self‐splicing intron of the LSUrRNA precursor is absent in Dexiostoma and Glaucoma and was likely acquired subsequent to the "australis/borealis" split; in some instances, its sequence is diagnostic of species. Tetrahymena americanis, T. elliotti, T. gruchyi n. sp., and T. borealis, together accounted for >50% of isolates, consistent with previous findings for established species. The biogeographic range of species found previously in Austria, China, and Pakistan was extended to the Nearctic; some species show evidence of population structure consistent with endemism. Most species were most frequently collected from ponds or lakes, while others, particularly Dexiostoma species, were collected most often from streams or rivers. The results suggest that perhaps hundreds of species remain to be discovered, particularly if collecting is global and includes hosts of parasitic forms. [ABSTRACT FROM AUTHOR]

Abstract: The morphology and morphogenesis of a new soil hypotrich ciliate, Sterkiella multicirrata sp. nov., was investigated using live observation and protargol staining. The new species is characterised by: body elliptical, 110–180 × 45–75 μm in vivo, an average of 35 adoral membranelles; usually 19 frontoventral‐transverse cirri, consisting of three frontal, five frontoventral, one buccal, four postoral ventral, two pretransverse, and four transverse cirri; four macronuclear nodules, and 2–5 micronuclei. S. multicirrata sp. nov. differs from its congeners mainly in the number of frontoventral‐transverse cirri and macronuclear nodules. Morphogenesis of the new species is similar to its congeners; the primary difference exists in the segmentation of the frontoventral‐transverse cirral anlagen, which is usually generated in a 1:2:3:3:5:5 pattern. Based on the small subunit ribosomal DNA sequence, the phylogenetic position of the new species is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Two amoeboid organisms of the genera Sappinia Dangeard, 1896 and Rosculus Hawes, 1963 were identified in a sample containing king penguin guano. This sample, collected in the Subantarctic, enlarges the list of fecal habitats known for the presence of coprophilic amoebae. The two organisms were co‐isolated and subcultured for over 6 mo, with continuous efforts being invested to separate each one from the mixed culture. In the mixed culture, Rosculus cells were fast growing, tolerated changes in culturing conditions, formed cysts, and evidently were attracted by Sappinia trophozoites. The separation of the Rosculus strain was accomplished, whereas the Sappinia strain remained intermixed with inseparable Rosculus cells. Sappinia cell populations were sensitive to changes in culturing conditions; they improved with reduction of Rosculus cells in the mixed culture. Thick‐walled cysts, reportedly formed by Sappinia species, were not seen. The ultrastructure of both organisms was congruent with the currently accepted generic characteristics; however, some details were remarkable at the species level. Combined with the results of phylogenetic analyses, our findings indicate that the ultrastructure of the glycocalyx and the presence/absence of the Golgi apparatus in differential diagnoses of Sappinia species require a critical re‐evaluation. [ABSTRACT FROM AUTHOR]

Abstract: The about 1,000 species of tintinnid ciliates are identified and classified almost exclusively based on their lorica features, although the shortcomings of this structure are well‐known, e.g. causing uncertain species limitations and nonmonophyletic taxa. Hence, the present redescription of Tintinnopsis everta Kofoid and Campbell, 1929 considers not only the lorica characteristics, but focuses on cell and genetic features. The species is redescribed from the North Atlantic and adjacent sea areas, namely the east coast of the USA, using live observation, protargol‐stained material, scanning electron microscopy, and genetic analyses. The main stages of cell division are described, and the species’ phylogenetic relationships are inferred from morphological data and the small subunit ribosomal RNA gene sequence. The estimates of its biogeographical distribution and autecology are based on a literature survey. The species is characterised by a complex somatic ciliary pattern with a unique position of the posterior kinety and a conspicuously large distance between the somatic ciliary fields and the collar membranelles. The phylogenetic relationships of Tintinnopsis everta vary in the molecular trees depending on the algorithms used and are, therefore, regarded as unresolved. Nevertheless, the new kind of complex somatic ciliary pattern distinctly contributes to a better understanding of the tintinnid biodiversity and evolution and provides features for a future split of the nonmonophyletic genus Tintinnopsis. [ABSTRACT FROM AUTHOR]

Abstract: Three new cyrtophorian ciliates isolated from coastal areas of China were described based on morphological and genetic data. The Chlamydodon mnemosyne‐like species Chlamydodon similis sp. n. differs from its congeners mainly by its number of somatic kineties. Chlamydodon oligochaetus sp. n. is distinguished from its congeners mainly by having fewer somatic kineties, and/or an elongated body shape. Chlamydodon crassidens sp. n. is characterized mainly by an inverted triangular body shape, a posteriorly interrupted cross‐striated band (5–6 μm wide), and a large cytostome. Moreover, we provided small‐subunit (SSU) rDNA sequences of C. similis sp. n. and C. oligochaetus sp. n. Maximum likelihood (ML) and Bayesian inference (BI) consistently placed C. similis sp. n. as a sister to C. paramnemosyne, but showed different branching position of C. oligochaetus sp. n., which may be due to a low taxon sampling in the Chlamydodontidae and/or an insufficient resolution of the marker gene at species level. [ABSTRACT FROM AUTHOR]

Abstract: The opisthokonts constitute a eukaryotic supergroup divided into two main clades: the holozoans, which include animals and their unicellular relatives, and the holomycotans, which include fungi, opisthosporidians, and nucleariids. Nucleariids are phagotrophic filose amoebae that phenotypically resemble more their distant holozoan cousins than their holomycotan phylogenetic relatives. Despite their evolutionary interest, the diversity and internal phylogenetic relationships within the nucleariids remain poorly studied. Here, we formally describe and characterize by molecular phylogeny and microscopy observations Parvularia atlantis gen. et sp. nov. (formerly Nuclearia sp. ATCC 50694), and compare its features with those of other nucleariid genera. Parvularia is an amoebal genus characterized by radiating knobbed and branching filopodia. It exhibits prominent vacuoles observable under light microscopy, a cyst‐like stage, and completely lacks cilia. P. atlantis possesses one or two nuclei with a central nucleolus, and mitochondria with flat or discoid cristae. These morphological features, although typical of nucleariids, represent a combination of characters different to those of any other described Nuclearia species. Likewise, 18S rRNA‐based phylogenetic analyses show that P. atlantis represents a distinct lineage within the nucleariids. [ABSTRACT FROM AUTHOR]

Abstract: A complex of closely related Mallomonas taxa belonging to the section Papillosae, M. kalinae Řezáčová and M. rasilis Dürrschmidt, has been studied in detail by molecular and morphometric methods. Our investigations uncovered the existence of a new species found in water bodies in Vietnam, which we describe here as Mallomonas furtiva sp. nov. This taxon is morphologically very similar to M. kalinae, from which it differs by minute, but statistically significant morphological differences on the structure of silica scales. Indeed, the principal component analysis of morphological traits measured on silica scales significantly separates all three species in the complex. Mallomonas kalinae and M. furtiva differ by number of papillae on the shield and the dome, as well as by the scale sizes. Likewise, Mallomonas rasilis and M. furtiva are primarily differentiated by the absence of submarginal anterior ribs on silica scales of the former species. Phylogenetic analyses showed that Mallomonas furtiva is closely related to M. kalinae, with which it formed a highly supported lineage. Distribution patterns of all three studied taxa are further discussed. [ABSTRACT FROM AUTHOR]

As a result of anthropogenic influences and global climate change, emerging infectious marine diseases are thought to be increasingly more common and more severe than in the past. The aim of our investigation was to confirm the presence of Labyrinthula, the aetiological agent of the seagrass wasting disease, in Southeastern Australia and provide the first isolation and characterisation of this protist, in Australia. Colonies and individual cells were positively identified as Labyrinthula using published descriptions, diagrams, and photographs. Their identity was then confirmed using DNA barcoding of a region of the 18S rRNA gene. Species level identification of isolates was not possible as the taxonomy of the Labyrinthula is still poorly resolved. Still, a diversity of Labyrinthula was isolated from small sections of the southeast coast of Australia. The isolates were grouped into three haplotypes that are biogeographically restricted. These haplotypes are closely related to previously identified saprotrophic clades. The study highlights the need for further investigation into the global distribution of Labyrinthula, including phylogenetic pathogenicity and analysis of host-parasite interactions in response to stressors. Given the results of our analyses, it is prudent to continue research into disease and epidemic agents to better prepare researchers for potential future outbreaks. [ABSTRACT FROM AUTHOR]

Five amoeboid organisms of different origin (isolated from fish organs, soil and digestive tract of earthworm) that shared light microscopical and ultrastructural features including type and arrangement of mitochondrial cristae were subjected to phylogenetic analyses based on sequences of SSU rDNA and protein coding genes (actin, cytochrome oxidase I, and eukaryotic elongation factor 2). The reconstruction of multigene phylogeny of the strains studied (i) revealed that they belong to the same single-genus Copromyxa clade; (ii) strongly supported position of Copromyxa cantabrigiensis (syn. Hartmannella cantabrigiensis) within the genus; (iii) together with comparisons of light and electron microscopy data justified reclassification of Cashia limacoides (syn. Vexillifera expectata) to Copromyxa limacoides n. comb., and (iv) justified description of a new species, Copromyxa laresi n. sp. [ABSTRACT FROM AUTHOR]

A new species of lobosean amoeba, Stenamoeba polymorpha n. sp., was isolated from the diarrheic stool of a domesticated horse in Great Falls Virginia, U.S. It shares characteristics with the five other described Stenamoeba species. However, electron microscopy revealed S. polymorpha has a substantially thickened cell surface lamina. Under light microscopy, the amoebae had a dynamic polymorphic appearance because hyaloplasm readily formed and resorbed subpseudopodia from any peripheral region of the cell. While in locomotion, the amoebae produced subpseudopodia that led and alternated the direction of movement with an apparent zigzag path. Sometimes, stationary amoebae had a vertical cell posture that was substantially taller than wide or long. The new species description is also supported by small subunit ribosomal ribonucleic acid gene analyses using phylogenies with both broad and narrow taxon sampling, pairwise nucleotide comparisons, and in-silico secondary structure predictions. The latter suggested Stenamoeba spp. discriminatory motifs in variable region eight. Stenamoeba polymorpha n. sp. is the first of its genus to be recovered from mammal feces, the first to yield a potential group one intron and the second described from North America. Here, the phylogenies suggest Stenamoeba limacina is this new species' nearest known relative. [ABSTRACT FROM AUTHOR]

Species determination is crucial in biodiversity research. In tintinnids, identification is based almost exclusively on the lorica, despite its frequent intraspecific variability and interspecific similarity. We suggest updated procedures for identification and, depending on the aim of the study, further steps to obtain morphological, molecular, and ecological data. Our goal is to help improving the collection of information (e.g. species re-/descriptions and DNA barcodes) that is essential for generating a natural tintinnid classification and a reliable reference for environmental surveys. These suggestions are broadly useful for protistologists because they exemplify data integration, quality/effort compromise, and the need for scientific collaborations. [ABSTRACT FROM AUTHOR]

We described the phylogenetic affiliation, development in cultures and ultrastructural features of a trypanosome of Leptodacylus chaquensis from the Pantanal biome of Brazil. In the inferred phylogeny, this trypanosome nested into the Anura clade of the basal Aquatic clade of Trypanosoma, but was separate from all known species within this clade. This finding enabled us to describe it as Trypanosoma herthameyeri n. sp., which also infects other Leptodacylus species from the Pantanal and Caatinga biomes. Trypanosoma herthameyeri multiplies as small rounded forms clumped together and evolving into multiple-fission forms and rosettes of epimastigotes released as long forms with long flagella; scarce trypomastigotes and glove-like forms are common in stationary-phase cultures. For the first time, a trypanosome from an amphibian was observed by field emission scanning electron microscopy, revealing a cytostome opening, well-developed flagellar lamella, and many grooves in pumpkin-like forms. Transmission electron microscopy showed highly developed Golgi complexes, relaxed catenation of KDNA, and a rich set of spongiome tubules in a regular parallel arrangement to the flagellar pocket as confirmed by electron tomography. Considering the basal position in the phylogenetic tree, developmental and ultrastructural data of T. herthameyeri are valuable for evolutionary studies of trypanosome architecture and cell biology. [ABSTRACT FROM AUTHOR]

Sorodiplophrys stercorea is a sorocarpic organism that utilizes filose pseudopodia for locomotion and absorptive nutrition. It has traditionally been considered to be a member of the Labyrinthulae based on its morphology. Its closest relatives were thought to be species in the taxon Diplophrys. Since the genus Diplophrys has been shown to be paraphyletic and S. stercorea has pseudopodia similar to some members of Rhizaria, we examined its relationship with other eukaryotes. We obtained four isolates from the dung of cow and horse, brought each into monoeukaryotic culture, and sequenced their SSU rRNA gene for phylogenetic analysis. All our isolates were shown to form a monophyletic group in the Labyrinthulae, nested in the Amphifiloidea clade. Our results demonstrate that Sorodiplophrys is more closely related to species of the genus Amphifila than to Diplophrys and represents an additional independent origin of sorocarpic multicellularity among eukaryotes. This study represents the first confirmed sorocarpic lifestyle in the Stramenopiles. [ABSTRACT FROM AUTHOR]

The microsporidium parasitizing Inland Bearded Dragons Pogona vitticeps, and developing primarily in macrophages within foci of granulomatous inflammation of different organs, is described as a new species Encephalitozoon pogonae. Establishing the new species was based on sequencing the ITS-SSUrDNA region of the ribosomal gene and consequent SSUrDNA-inferred phylogenetic analyses, as well as on comparison of pathogenesis, host specificity, and ultrastructure among Encephalitozoon species and isolates. The new species is closely related to E. lacertae and E. cuniculi. Analysis of the literature suggests that this microsporidium has been reported previously as an unidentified microsporidian species or isolate of E. cuniculi and may represent a common infection in bearded dragons. All stages of E. pogonae develop in parasitophorous vacuoles. Uninucleate spores on methanol-fixed smears measured 2.1 x 1.1 µm, range 1.7-2.6 x 0.9-1.7 µm; on ultrathin sections spores measured 0.8-1.1 x 1.8-2.2 µm. Ultrastructural study revealed 3-6 polar filament coils, a mushroom-shaped polar disk, and a polar sac embracing half of the volume occupied by the lamellar polaroplast. In activated spores, polar filament everted eccentrically. The overall morphology and intracellular development of E. pogonae were similar to other Encepahalitozoon spp. We also review the existing data on microsporidia infecting reptiles. [ABSTRACT FROM AUTHOR]

The genus Entamoeba includes anaerobic lobose amoebae, most of which are parasites of various vertebrates and invertebrates. We report a new Entamoeba species, E. marina n. sp. that was isolated from a sample of tidal flat sediment collected at Iriomote Island, Okinawa, Japan. Trophozoites of E. marina were 12.8-32.1 μm in length and 6.8-15.9 μm in width, whereas the cysts were 8.9-15.8 μm in diam. and contained four nuclei. The E. marina cells contained a rounded nucleus with a small centric karyosome and uniformly arranged peripheral chromatin. Although E. marina is morphologically indistinguishable from other tetranucleated cyst-forming Entamoeba species, E. marina can be distinguished from them based on the combination of molecular phylogenetic analyses using SSU rDNA gene and the difference of collection sites. Therefore, we propose E. marina as a new species of the genus Entamoeba. [ABSTRACT FROM AUTHOR]

The genus Rhizomastix is a poorly known group of amoeboid heterotrophic flagellates living as intestinal commensals of insects, amphibians or reptiles, and as inhabitants of organic freshwater sediments. Eleven Rhizomastix species have been described so far, but DNA sequences from only a single species have been published. Recently, phylogenetic analyses confirmed a previous hypothesis that the genus belongs to the Archamoebae; however, its exact position therein remains unclear. In this study we cultured nine strains of Rhizomastix, both endobiotic and free-living. According to their light-microscopic morphology and SSU rRNA and actin gene analyses, the strains represent five species, of which four are newly described here: R. bicoronata sp. nov., R. elongata sp. nov., R. vacuolata sp. nov. and R. varia sp. nov. In addition, R. tipulae sp. nov., living in the intestine of crane flies, is separated from the type species, R. gracilis. We also examined the ultrastructure of R. elongata sp. nov., which revealed that it is more complicated than the previously described R. libera. Our data show that either the endobiotic lifestyle of some Rhizomastix species has arisen independently from other endobiotic archamoebae, or the free-living members of this genus represent a secondary switch from the endobiotic lifestyle. [ABSTRACT FROM AUTHOR]

Removing the requirement for cell culture has led to a substantial increase in the number of lineages of Entamoeba recognized as distinct. Surveying the range of potential host species for this parasite genus has barely been started and it is clear that additional sampling of the same host in different locations often identifies additional diversity. In this study, using small subunit ribosomal RNA gene sequencing, we identify four new lineages of Entamoeba, including the first report of Entamoeba from an elephant, and extend the host range of some previously described lineages. In addition, examination of microbiome data from a number of host animals suggests that substantial Entamoeba diversity remains to be uncovered. [ABSTRACT FROM AUTHOR]

Using a transmission electron microscopy-based approach, this study details the striking similarities between Cryptosporidium parvum and the gregarines during in vitro axenic development at high ultra-structural resolution. C. parvum zoites displayed three unusual regions within uninucleated parasites: epimerite-like, protomerite-like, and the cell body; these regions exhibited a high degree of morphological similarity to gregarine-like trophozoites. The presence of a mucron-like bulging structure at the side of the free ovoid gregarine-like zoites was observed after 2 h of cultivation. An irregular pattern of epicytic-like folds were found to cover the surface of the parasites 24 h postcultivation. Some extracellular stages were paired in laterocaudal or side-side syzygy, with the presence of a fusion zone between some of these zoites. The present findings are in agreement with phylogenetic studies that have proposed a sister relationship with gregarines. Cryptosporidium appears to exhibit tremendous variety in cell structure depending on the surrounding environment, thereby mimicking the 'primitive' gregarines in terms of the co-evolution strategy between the parasites and their environments. Given this degree of similarity, different aspects of the evolutionary biology of Cryptosporidium need to be examined, considering the knowledge gained from the study of gregarines. [ABSTRACT FROM AUTHOR]

Polytomella strain SAG 63-10 was first described by Pringsheim (1963) as Polytomella piriformis nomen nudum. The current study validates the name Polytomella piriformis following the International Code of Nomenclature for algae, fungi, and plants ( ICN). We present 18S rRNA sequences of SAG 63-10 and several other Polytomella strains, which, along with existing mitochondrial DNA sequences, clearly distinguishes P. piriformis n. sp. from other available Polytomella species. The first type material of the species is presented, as well as an illustration and micrographs. Our own observations of P. piriformis SAG 63-10 are compared to Pringsheim's description and to descriptions of other valid Polytomella spp. [ABSTRACT FROM AUTHOR]

The small and large nuclear subunit molecular phylogeny of the genus Prorocentrum demonstrated that the species are dichotomized into two clades. These two clades were significantly different (one-factor ANOVA, p < 0.01) with patterns compatible for both small and large subunit Bayesian phylogenetic trees, and for a larger taxon sampled dinoflagellate phylogeny. Evaluation of the molecular divergence levels showed that intraspecies genetic variations were significantly low ( t-test, p < 0.05), than those for interspecies variations (> 2.9% and > 26.8% dissimilarity in the small and large subunit [D1/D2], respectively). Based on the calculated molecular divergence, the genus comprises two genetically distinct groups that should be considered as two separate genera, thereby setting the pace for major systematic changes for the genus Prorocentrum sensu Dodge. Moreover, the information presented in this study would be useful for improving species identification, detection of novel clades from environmental samples. [ABSTRACT FROM AUTHOR]

Microalgae in the division Haptophyta may be difficult to identify to species by microscopy because they are small and fragile. Here, we used high-throughput sequencing to explore the diversity of haptophytes in outer Oslofjorden, Skagerrak, and supplemented this with electron microscopy. Nano- and picoplanktonic subsurface samples were collected monthly for 2 yr, and the haptophytes were targeted by amplification of RNA/cDNA with Haptophyta-specific 18S ribosomal DNA V4 primers. Pyrosequencing revealed higher species richness of haptophytes than previously observed in the Skagerrak by microscopy. From ca. 400,000 reads we obtained 156 haptophyte operational taxonomic units (OTUs) after rigorous filtering and 99.5% clustering. The majority (84%) of the OTUs matched environmental sequences not linked to a morphological species, most of which were affiliated with the order Prymnesiales. Phylogenetic analyses including Oslofjorden OTUs and available cultured and environmental haptophyte sequences showed that several of the OTUs matched sequences forming deep-branching lineages, potentially representing novel haptophyte classes. Pyrosequencing also retrieved cultured species not previously reported by microscopy in the Skagerrak. Electron microscopy revealed species not yet genetically characterised and some potentially novel taxa. This study contributes to linking genotype to phenotype within this ubiquitous and ecologically important protist group, and reveals great, unknown diversity. [ABSTRACT FROM AUTHOR]

A cryptic species of the Tetrahymena pyriformis complex, Tetrahymena australis, has been known for a long time but never properly diagnosed based on taxonomic methods. The species name is thus invalid according to the International Code of Zoological Nomenclature. Recently, a population isolated from a freshwater lake in Wuhan, China was investigated using live observations, silver staining methods and gene sequence data. This organism can be separated from other described species of the T. pyriformis complex by its relatively small body size, the number of somatic kineties and differences in sequences of two genes, namely the small subunit ribosomal RNA ( SSU rRNA) and the mitochondrial cytochrome c oxidase subunit I ( cox1). We compared the SSU rRNA gene sequences of all available Tetrahymena species to reveal the nucleotide differences within this genus. The sequence of the Wuhan population is identical to two sequences of a previously isolated strain of T. australis ( ATCC #30831). Phylogenetic analyses indicate that these three sequences (X56167, M98015, KT334373) cluster with Tetrahymena shanghaiensis ( EF070256) in a polytomy. However, sequence divergence of the cox1 gene between the Wuhan population and another strain of T. australis ( ATCC #30271) is 1.4%, suggesting that these may represent different subspecies. [ABSTRACT FROM AUTHOR]