An ultrastructural comparison of the mitotic apparatus,feeding apparatus,flagellar apparatus and cytoskeleton in euglenoids and kinetoplastids

Summary The euglenoids and kinetoplastids form a diverse assemblage of organisms which show no obvious phylogenetic relationship with other flagellates. An ultrastructural examination and comparison of the flagellar apparatus, the feeding apparatus, and mitotic nucleus indicate a number of shared morphological features which support a common ancestry for the two groups. Of particular interest is the euglenoid,Petalomonas cantuscygni, which shares many of the ultrastructural features common to both groups. Based on the data presented, we hypothesize that a euglenoid with features similar to those now present inP. cantuscygni was ancestral to both the euglenoid and kinetoplastid lines.Abbrevation MTR complex of reinforcing microtubules     

PHYLOGENY OF PHAGOTROPHIC EUGLENIDS (EUGLENOZOA): A MOLECULAR APPROACH BASED ON CULTURE MATERIAL AND ENVIRONMENTAL SAMPLES1

Molecular studies based on small subunit (SSU) rDNA sequences addressing euglenid phylogeny hitherto suffered from the lack of available data about phagotrophic species. To extend the taxon sampling, SSU rRNA genes from species of seven genera of phagotrophic euglenids were investigated. Sequence analyses revealed an increasing genetic diversity among euglenid SSU rDNA sequences compared with other well‐known eukaryotic groups, reflecting an equally broad diversity of morphological characters among euglenid phagotrophs. Phylogenetic inference using standard parsimony and likelihood approaches as well as Bayesian inference and spectral analyses revealed no clear support for euglenid monophyly. Among phagotrophs, monophyly of Petalomonas cantuscygni and Notosolenus ostium, both comprising simple ingestion apparatuses, is strongly supported. A moderately supported clade comprises phototrophic euglenids and primary osmotrophic euglenids together with phagotrophs, exhibiting a primarily flexible pellicle composed of numerous helically arranged strips and a complex ingestion apparatus with two supporting rods and four curved vanes. Comparison of molecular and morphological data is used to demonstrate the difficulties to formulate a hypothesis about how the ingestion apparatus evolved in this group.     

Free-living heterotrophic euglenids from freshwater sites in mainland Australia

This paper presents new data on free-living heterotrophic euglenids (Euglenozoa, Protista) that were found at several freshwater sites in New South Wales, Northern Territory, and Queensland, Australia. Thirty-six species are described with uninterpreted records based on light-microscopy. The records include accounts of two new taxa: Heteronema pterbicanov. spec., Sphenomonas alburiae nov. spec., and of six new combinations: Dinema dimorphum (Skuja, 1932) nov. comb., Notosolenus mediocanellatus(Stein, 1878) nov. comb., Notosolenus steini (Klebs, 1893) nov. comb., Ploeotia obliqua(Klebs, 1893) nov. comb., Ploeotia plana(Christen, 1959) nov. comb., and Rhabdomonas mirabilis (Playfair, 1921) nov. comb. We also introduce the following: Astasia skvortzovi nom. nov., Heteronema hexagonum var. elegans (Playfair, 1921) nov. comb., Petalomonas compressa (Schewiakoff, 1893) nov. comb., and Jenningsia deflexumvar dextrum (Shi, 1975) nov. comb. All records of heterotrophic euglenids in Australia are reviewed. The majority of species reported here have also been found at other locations worldwide, and we find little or no evidence that there is endemism in this group.     

Ultrastructural and immunocytochemical investigation of paramylon combined with new 18S rDNA-based secondary structure analysis clarifies phylogenetic affiliation of <Emphasis Type="Italic">Entosiphon sulcatum</Emphasis> (Euglenida: Euglenozoa)

The phylogeny of phagotrophic euglenids is widely based on nuclear small subunit ribosomal DNA (18S rDNA) sequence data, but most analyses suffer from weakness in statistical support regarding the “connecting backbone” between monophyletic clades. Moreover, the position of Entosiphon has remained unclear. Testing the 18S rDNA capability for a phylogeny of phagotrophic euglenids, we isolated sequences of Peranema sp. and Ploeotia edaphica and utilized secondary structure data as a prerequisite for recognition of homologous positions. We found a unique, clade-specific nucleotide substitution in the deduced 18S rDNA helix 44. Since our 18S rDNA phylogenies could only in part resolve positions of phagotrophic lineages, but did not verify that of Entosiphon, we investigated the phagotrophic key taxa Peranema trichophorum, Petalomonas cantuscygni, Ploeotia costata, and Entosiphon sulcatum ultrastructurally. Additionally, we explored the presence or absence of the euglenid reserve carbohydrate paramylon by specific staining with monoclonal anti-β-1,3-glucan antibodies. Paramylon was found to be clearly present in P. trichophorum and E. sulcatum, but was absent in Pt. cantuscygni and Pl. costata. Combined results of our molecular, ultrastructural, and immunocytochemical investigations suggest that Entosiphon sulcatum is the sister taxon of a monophyletic euglenid crown clade, characterized by a helical pellicle, which we propose to rename. This phylogenetic affiliation is confirmed by a clade-specific primary absence of the unique nucleotide substitution in helix 44 and by the common presence of paramylon.     

The cell biology of peritrichous flagella in Bacillus subtilis

Bacterial flagella are highly conserved molecular machines that have been extensively studied for assembly, function and gene regulation. Less studied is how and why bacteria differ based on the number and arrangement of the flagella they synthesize. Here we explore the cell biology of peritrichous flagella in the model bacterium Bacillus subtilis by fluorescently labelling flagellar basal bodies, hooks and filaments. We find that the average B. subtilis cell assembles approximately 26 flagellar basal bodies and we show that basal body number is controlled by SwrA. Basal bodies are assembled rapidly (< 5 min) but the assembly of flagella capable of supporting motility is rate limited by filament polymerization (> 40 min). We find that basal bodies are not positioned randomly on the cell surface. Rather, basal bodies occupy a grid‐like pattern organized symmetrically around the midcell and that flagella are discouraged at the poles. Basal body position is genetically determined by FlhF and FlhG homologues to control spatial patterning differently from what is seen in bacteria with polar flagella. Finally, spatial control of flagella in B. subtilis seems more relevant to the inheritance of flagella and motility of individual cells than the motile behaviour of populations.     

DEVELOPMENT OF THE FLAGELLAR APPARATUS AND FLAGELLAR POSITION IN THE COLONIAL GREEN ALGA PLATYDORINA CAUDATA (CHLOROPHYCEAE)1

The ultrastructure of the flagellar apparatus in pre-inversion and inversion stages of Platydorina resembles that of Chlamydomonas in having 180° rotational symmetry and clockwise absolute orientation. Basal bodies are in a “V” configuration and connected by one distal and two proximal fibers. Alternating two- and four-membered microtubular rootlets are cruciately arranged. During maturation, the basal bodies rotate and separate, and 180° rotational symmetry is lost. Simultaneously, each proximal fiber detaches from one of the functional basal bodies, and the distal fiber detaches from both. The mature apparatus has widely separated and nearly parallel basal bodies. Flagellar orientation in Platydorina is completed just after inversion and a flattening of the colony called intercalation, resulting in the pairs of flagella of neighboring cells extending from the colony in opposite directions in an alternating fashion. Flagellar orientation and separated basal bodies minimize the interference between the flagella of neighboring cells. Basal bodies and rootlets of the two intercalated halves of a colony rotate, resulting in the effective strokes of the flagella of every cell being towards the colonial posterior. The flagella of each cell beat with an effective stroke in the direction of the two inner rootlets. The flagella have an asymmetrical ciliary type beat. The rotated, separated, and parallel basal bodies, together with the nearly parallel rootlets probably are adaptations for movement of this colonial volvocalean alga. The flagellar apparatus in immature stages of Platydorina lends support to the suggestion that the alga has evolved from a Chlamydomonas-like ancestor.     

PHYLOGENETIC RELATIONSHIPS OF SELECTED EUGLENOID GENERA BASED ON MORPHOLOGICAL AND MOLECULAR DATA1

The small subunit rRNA (SSU rRNA) coding regions sequenced from the euglenoids Petalomonas cantuscygni, Peranema trichophorum, and Khawkinea quartana were used to assess the phylogenetic relationships of these genera within the Euglenozoa. Phylogenies derived from distance, parsimony, and maximum likelihood methods infer that the euglenoids and kinetoplastids form sister clades within a monophyletic assemblage. Distances representative of closely related lineages separate the genera within the Kinetoplastida, whereas larger distance values separate genera within the euglenoid assemblage. The results of the morphological and molecular studies suggest that phagotrophy arose early in the euglenozoan lineage with the subsequent acquisition of phototrophy, osmotrophy, and parasitism. Phagotrophic euglenoids with a pellicle composed of longitudinal strips appear to have diverged prior to genera with helically arranged strips. This study suggests that the hypothetical ancestor to the Euglenozoa was a phagotroph with two flagella, both containing paraxonemal rods. Furthermore, its basal bodies contained proximal cartwheels, were connected by a prominent fiber, and were anchored with three asymmetrically arranged flagellar roots.     

The Morphology,Ultrastructure and SSU rRNA Gene Sequence of a New Freshwater Flagellate,Neobodo borokensis n. sp. (Kinetoplastea,Excavata)

A small free‐living freshwater bacteriotrophic flagellate Neobodo borokensis n. sp. was investigated by electron microscopy and analysis of its SSU ribosomal RNA gene. This protist has paraxonemal rods of typical bodonid structure in the flagella, mastigonemes on the proximal part of the posterior flagellum, two nearly parallel basal bodies, a compact kinetoplast, and discoid mitochondrial cristae. The flagellar pocket is supported by three microtubular roots (R1, R2 and R3) originating from the kinetosome. The cytopharynx is supported by the root R2, a microtubular prism, cytopharynx associated additional microtubules (CMT) and cytostome associated microtubules (FAS) bands. Symbiotic bacteria and small glycosomes were found in the cytoplasm. Cysts have not been found. The flagellate prefers freshwater habitats, but tolerates salinity up to 3–4‰. The overall morphological and ultrastructural features confirm that N. borokensis represents a new species of the genus Neobodo. Phylogenetic analysis of SSU rRNA genes is congruent with the ultrastructure and strongly supports the close relationship of N. borokensis to Neobodo saliens, N. designis, Actuariola, and a misidentified sequence of “Bodo curvifilus” within the class Kinetoplastea.     

Viscous drag on the flagellum activates Bacillus subtilis entry into the K‐state

Bacillus subtilis flagella are not only required for locomotion but also act as sensors that monitor environmental changes. Although how the signal transmission takes place is poorly understood, it has been shown that flagella play an important role in surface sensing by transmitting a mechanical signal to control the DegS‐DegU two‐component system. Here we report a role for flagella in the regulation of the K‐state, which enables transformability and antibiotic tolerance (persistence). Mutations impairing flagellar synthesis are inferred to increase DegU‐P, which inhibits the expression of ComK, the master regulator for the K‐state, and reduces transformability. Tellingly, both deletion of the flagellin gene and straight filament (hag^A233V) mutations increased DegU phosphorylation despite the fact that both mutants had wild type numbers of basal bodies and the flagellar motors were functional. We propose that higher viscous loads on flagellar motors result in lower DegU‐P levels through an unknown signaling mechanism. This flagellar‐load based mechanism ensures that cells in the motile subpopulation have a tenfold enhanced likelihood of entering the K‐state and taking up DNA from the environment. Further, our results suggest that the developmental states of motility and competence are related and most commonly occur in the same epigenetic cell type.     

Evidence for a functional membrane barrier in the transition zone between the flagellum and cell body of Chlamydomonas eugametos gametes

Evidence is presented which supports the concept of a functional membrane barrier in the transition zone at the base of each flagellum of Chlamydomonas eugametos gametes. This makes it unlikely that agglutination factors present on the surface of the cell body can diffuse or be transported to the flagellar membrane. The evidence is as follows: 1) The glycoprotein composition of the flagellar membrane is very different to that of the cell-body plasma membrane. 2) The flagella of gametes treated with cycloheximide, tunicamycin or , -dipyridyl become non-agglutinable but the source of agglutination factors on the cell body is not affected. 3) Even under natural conditions when the flagella are non-agglutinable, for example in vis-à-vis pairs or in appropriate cell strains that are non-agglutinable in the dark, the cell bodies maintain the normal complement of active agglutinins. 4) When flagella of living cells are labeled with antibodies bound to fluorescein, the label does not diffuse onto the cell-body surface. 5) When gametes fuse to form vis-à-vis pairs, the original mating-type-specific antigenicity of each cell body is slowly lost (probably due to the antigens diffusing over both cell bodies), while the specific antigenicity of the flagellar surface is maintained. Even when the flagella of vis-à-vis pairs are regenerated from cell bodies with mixed antigenicity, the antigenicity of the flagella remains matingtype-specific. 6) Evidence is presented for the existence of a pool of agglutination factors within the cell bodies but not on the outer surface of the cells.Abbreviations and symbols CHI cycloheximide - GTC guaniline thiocyanate - mt ⁺/mt ^- mating type plus or minus - PAS Periodic-acid-Schiff reagent - SDS sodium dodecyl sulphate     

Sexual agglutination in Chlamydomonas eugametos before and after cell fusion

A new study of sexual agglutination between Chlamydomonas eugametos gametes and between vis-à-vis pairs has been made using techniques that allow one to distinguish between the flagella or cell bodies of individual mating types (mt⁺ or mt^-). It is shown that before mt⁺ and mt^- gametes fuse in pairs, their flagella, which adhere over their whole length, are maintained in a particular conformation around the mt^- cell body. In clumps of agglutinating gametes the cells are asymmetrically distributed with the mt⁺ gametes constituting the outer surface of the clumps with the mt^- gametes on the inside. The flagella are then all directed towards the middle of the clump. This orientation of the flagella is maintained for approx. 8 min after cell fusion before the vis-à-vis pair becomes motile. At this stage, all the flagellar tips are activated. The original mt⁺ flagellar tips then deactivate and swimming is resumed. The original mt^- flagella remain immotile and activated after cell fusion and eventually shorten by a third, but only 30 min or more after fusion. Motile vis-à-vis pairs eventually settle to the substrate when the gamete bodies fuse completely to form a zygote. Settling vis-à-vis pairs are attracted to those that have already settled, to glutaraldehyde-fixed pairs and to flagella isolated from mt^- gametes. They are not chemotactically attracted, rather they are weakly agglutinated. Living vis-à-vis pairs can be shown to aggregate in rows with the cell bodies lying side by side. It is argued that the flagellar agglutination sites involved in gamete recognition are also involved in vis-à-vis pair aggregationAbbreviations mt^+/- mating type plus or minus - FTA flagellar tip activation     

Coordinate Synthesis but Discrete Localization of Homologous N‐Glycosylated Proteins,CLP and CLB,in Naegleria pringsheimi Flagellates

The synchronous amoebae‐to‐flagellates differentiation of Naegleria pringsheimi has been used as a model system to study the formation of eukaryotic flagella. We cloned two novel genes, Clp, Cl ass I on p lasma membrane and Clb, Cl ass I at b asal bodies, which are transiently expressed during differentiation and characterized their respective protein products. CLP (2,087 amino acids) and CLB (1,952 amino acids) have 82.9% identity in their amino acid sequences and are heavily N‐glycosylated, leading to an ~ 100 × 10³ increase in the relative molecular mass of the native proteins. In spite of these similarities, CLP and CLB were localized to distinct regions: CLP was present on the outer surface of the plasma membrane, whereas CLB was concentrated at a site where the basal bodies are assembled and remained associated with the basal bodies. Oryzalin, a microtubule toxin, inhibited the appearance of CLP on the plasma membrane, but had no effect on the concentration of CLB at its target site. These data suggest that N. pringsheimi uses separate mechanisms to transport CLP and CLB to the plasma membrane and to the site of basal body assembly, respectively.     

ULTRASTRUCTURE OF THE FLAGELLAR APPARATUS OF PYROBOTRYS (CHLOROPHYCEAE)1

The flagellar apparatus of Pyrobotrys has a number of features that are typical of the Chlorophyceae, but others that are unusual for this class. The two flagella are inserted at the apex, but they extend to the side of the cell toward the outside of the colony, here designated as the ventral side. Four basal bodies are present, two of which extend into flagella. Four microtubular rootlets alternate between the functional and accessory basal bodies. In each cell, the two ventral rootlets are nearly parallel, but the dorsal rootlets are more widely divergent. The rootlets alternate between two and four microtubules each. A striated distal fiber connects the two functional basal bodies in the plane of the flagella. Two additional, apparently nonstriated, fibers connect the basal bodies proximal to the distal fiber. Another striated fiber is associated with each four-membered rootlet near its insertion into the flagellar apparatus. A fine periodic component is associated with each two-membered rootlet. A rhizoplast-like structure extends into the cell from each of the functional basal bodies. The arrangement of these components does not reflect the 180° rotational symmetry that is usually present in the Chlorophyceae, but appears to be derived from a more symmetrical ancestor. It is suggested that the form of the flagellar apparatus is associated with the unusual colony structure of Pyrobotrys.     

Swimming behavior and ultrastructure of sperm of<Emphasis Type="Italic"> Lygodium japonicum</Emphasis> (Pteridophyta)

Swimming behavior of the sperm of Lygodium japonicum (Pteridophyta) and the associated ultrastructure of the flagellar apparatus were studied by video microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The sperm has approximately 70 flagella that emerge from a sinistrally-coiled flagellar apparatus, and swims forward by ciliary beat of these flagella. Backward swimming was not observed even after sperm collided with obstacles. Video microscopy showed that the flagella of the swimming sperm are oriented laterally and oblique-anteriorly. TEM and SEM observations revealed that the basal bodies of these flagella are arranged in at least two rows and oriented in the same directions as observed by video microscopy. These basal bodies (flagella) are categorized into two types according to their orientation: group I (laterally directed) and group II (oblique-anteriorly directed). The directionality of the basal bodies appears to be fixed by electron-dense material around their base. The outer dynein arms of the flagellar axoneme are entirely absent. These morphological characteristics of basal bodies (flagella) may relate to the lack of backward swimming behavior of the sperm. Based on these results, the evolution of swimming behavior in the archegoniates is discussed in connection with lack of backward swimming in a distantly related green alga, Mesostigma viride, and the Streptophyta.     

Comparative ultrastructure of the zoospores of nine species ofNeochloris (Chlorophyta)

Nine species ofNeochloris can be divided into three groups on the basis of comparative ultrastructure of the flagellar apparatus, the cell wall and the pyrenoid of zoospores. In Group I,N. wimmeri andN. minuta, zoospores are thin-walled, pyrenoids are penetrated by stromal channels, and the basal bodies are in the clockwise absolute orientation and connected by the distal and two proximal fibers. In Group II,N. aquatica, N. vigenis, N. terrestris, N. pyenoidosa, andN. pseudostigmatica, zoospores are naked or covered by fuzzy material, pyrenoids are covered by a continuous starch sheath or invaginated by cytoplasmic channels, basal bodies are directly opposed, the distal fiber is differentiated into a ribbed structure at the central region, a striated microtubule-associated component (SMAC) is continuous between opposite two-membered rootlets and connected to the ribbed structure, proximal ends of basal bodies are covered by partial caps, each two-membered rootlet and a basal body are connected by a striated fiber to the X-membered rootlet associated with the opposite basal body, and the basal bodies, when oriented at wide angles, are joined at their proximal ends by core extensions. In Group III,N. pseudoalveolaris andN. cohaerens, zoospores are naked, pyrenoids are traversed by parallel thylakoids, basal bodies are in the counterclockwise absolute orientation and overlapped, and each X-membered rootlet is connected to the end of the opposite basal body by a terminal cap. It is suggested that the genusChlorococcopsis gen. nov. be erected for the Group I species. Group II, which includes the type species,N. aquatica, should be preserved asNeochloris. The group appears to be closely related to the coenobial generaPediastrum, Hydrodictyon, andSorastrum, and to have affinities with the coenocytic generaSphaeroplea andAtractomorpha as well. It is also suggested that the genusParietochloris gen. nov. be erected in thePleurastrophyceae for the species of Group III.     

Variation in the SSUrDNA of the Genus Protostelium Leads to a New Phylogenetic Understanding of the Genus and of the Species Concept for Protostelium mycophaga (Protosteliida,Amoebozoa)

Members of the genus Protostelium (including P. mycophaga, P. nocturnum, and P. okumukumu) are protosteloid amoebae commonly found in terrestrial habitats on dead plant matter. They, along with the closely allied nominal genus Planoprotostelium, containing the single species Pl. aurantium, all have an amoeboid trophic stage with acutely pointed subpseudopodia and orange lipid droplets in the granuloplasm. These amoebae form stalked fruiting bodies topped with a single, usually deciduous spore. The species are identified based on their fruiting body morphologies except for Pl. aurantium which looks similar to P. mycophaga in fruiting morphology, but has amoebae that can make flagella in liquid medium. We built phylogenetic trees using nuclear small subunit ribosomal DNA sequences of 35 isolates from the genera Protostelium and Planoprotostelium and found that (1) the nonflagellated P. nocturnum and P. okumukumu branch basally in the genus Protostelium, (2) the flagellate, Pl. aurantium falls within the genus Protostelium in a monophyletic clade with the nominal variety, P. mycophaga var. crassipes, (3) the cultures initially identified as Protostelium mycophaga can be divided into at least three morphologically recognizable taxa, P. aurantium n. comb., P. apiculatum n. sp., and P. m. rodmani n. subsp., as well as a paraphyletic assemblage that includes the remainder of the P. mycophaga morphotype. These findings have implications for understanding the ecology, evolution, and diversity of these amoeboid organisms and for using these amoebae as models for other amoeboid groups.     

A Century of Change in Macrophyte Abundance and Composition in Response to Agricultural Eutrophication

Clear Lake, Iowa, USA is a shallow, agriculturally eutrophic lake that has changed drastically over the past century. Eight macrophyte surveys since 1896 were pooled and examined to characterize long-term impacts of eutrophication on macrophyte community composition and relative abundance. Surveys in 1981 and 2000 revealed few submergent and floating-leaved species and a dominance in emergent species (Scirpus, Typha). Over the past century, however, species richness has declined from a high of 30 species in 1951 to 12 found today, while the community composition has shifted from submergent-(99%) to emergent-dominated floras (84%). Potamogeton praelongus was the first emergent species to disappear but was followed by several other clear water Potamogeton species. Several floating leaved and emergent genera increased in relative abundance with eutrophication, notably Nuphar, Nymphaea, Phragmites, Polygonum, Sagittaria, Scirpus, and Typha. P. pectinatus was present over the entire century due to its tolerance of eutrophic conditions. Macrophyte growth was generally light-limited, with 93% of the variance in relative abundance of submergent species explained by changes in water transparency. Clear Lake exhibits signs of alternative stable states, oscillating between clear and turbid water, coupled with high and low submerged species relative abundance. The maximum macrophyte richness occurred as the lake oscillated between submergent- and emergent-dominated states. Changes in the water level have also impacted macrophyte growth since the area of the lake occupied by emergent macrophytes was negatively correlated with water level. Strongest correlations indicated that macrophytes respond to water level variations with a 2-year time-lag.     

Response of root and sediment phosphatase activity to increased nutrients and salinity

Wetlands of northern Belize, distributed along a salinity gradient, are strongly phosphorus limited and dominated largely by three species of emergent macrophytes: Eleocharis cellulosa, Cladium jamaicense, and Typha domingensis. We assessed changes in root and sediment phosphatase activities of each species to simultaneous changes of nutrients (N, P) and salinity in a mesocosm experiment. Phosphorus and nitrogen treatment effects on both root and sediment phosphatase were highly significant for all the species, while salinity significantly affected root phosphatase activity in Cladium only. All species showed a significant negative correlation between root phosphatase activity and increasing tissue P content until a threshold of 0.2% P, 0.15% P and 0.12% P in Eleocharis, Cladium and Typha, respectively. There was also a significant negative correlation between soil available P and root and sediment phosphatases in all species. Activity of root phosphatases of Eleocharis and Typha were positively correlated with root tissue N. Both root and sediment phosphatases of all three species were positively correlated with soil available N. The strongest (positive) correlation was found between phoshatase activites and N/P ratios. The results confirmed that these systems are P-limited and that extracellular phosphatases respond to P enrichment by decreasing their activities. Expression of root phosphatase activity by dry root weight, sediment volume, or whole plant biomass gave very different relative results across nutrient treatments and species, suggesting that root phosphatase activities need to be interpreted in a wider context that considers root density.     

Neue und wenig bekannte Flagellaten aus dem Hausersee (Schweiz)

Zusammenfassung Eine Anzahl seltener oder neuer Flagellaten, welche im Zentrifugenplankton des Hausersees bei Andelfingen (Kt. Zürich, Schweiz) beobachtet wurden, werden beschrieben. Peridinium penardiforme, Strombomonas urceolata, Chlamydomonas insignis und Sphaerellopsis Lefèvrei wurrden bisher im Limnoplankton nur vereinzelt oder an geographisch weit voneinander entfernten Stellen festgestellt. Neu beschrieben werden insgesamt 11 Arten: Cryptomonas globosa, Amphidinium Skujae, Gymnodinium titubans, Peridinium sphaeroideum, Petalomonas pygmaea, Petalomonas elongata, Anisonema hexagonale, Carteria Huberi, Chlamydomonas deludens, Chlamydomonas opisthostigma, Chlamydomonas crassa.

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Summary Some rare or new flagellates, found in the Hausersee (Kt. Zurich, Switzerland) are described. Peridinium penardiforme, Strombomonas urceolata, Chlamydomonas insignis and Sphaerellopsis Lefèvrei, seldom found in limnological investigations, live euplanctical in the Hausersee. The new species described are: Cryptomonas globosa, Amphidinium Skujae, Gymnodinium titubans, Peridinium sphaeroideum, Petalomonas pygmaea, Petalomonas elongata, Anisonema hexagonale, Carteria Huberi, Chlamydomonas deludens, Chlamydomonas opisthostigma, Chlamydomonas crassa.