The first part of the 250 year history of tintinnid studies, “Pioneers of Tintinnid Studies,” traced the beginnings of the study of tintinnids from the first description in 1776, up to the appearance of Kofoid and Campbell’s 1929 monograph. Here the second part of the history is presented, the studies of the “Modern Era,” the period of 1930 to 2025, during which time over 700 works focused on tintinnids have been published. In this review, the modern history of tintinnid studies is traced through brief portrayals, vignettes, of 55 workers who have made significant contributions to our knowledge of living tintinnids over the last nearly 100 years. The vignettes show that a remarkable diversity of researchers have been engaged in tintinnid studies, from the early years up to the present day and the changes, with time, in the types of studies conducted. Finally, some of the interconnections among the modern era researchers are given suggesting that an early exposure to tintinnids, through an advisor or mentor, has characterized many tintinnid researchers.
The first tintinnid ciliate was discovered and described in 1776, using just five words. Although now 250 years old, the study of tintinnids is still a very active field. According to Google Scholar, in the last 10 years, 151 works have appeared with the term “tintinnid” in the title. Early works mostly concerned species descriptions. In contrast, the recent studies have focused on a wide variety of topics: ecology, phylogeny, physiology, behavior, and biogeography. Here the beginnings of the long and rich history of tintinnid studies are traced through the stories of early workers in the period from the first descriptions, up to and including the appearance in 1929 of Kofoid and Campbell’s landmark treatise and its revision in 1939. Many are unaware of the fact that early protistologists who worked on tintinnids were prestigious biologists of their time, now known as important contributors not only to our knowledge of tintinnids, but also other groups of protists. There were ardent defenders of Darwin among the early workers. There were also often interesting interconnections between the early workers, while some began studying tintinnids almost by accident. A companion paper will shine a light on modern workers of tintinnid studies.
High-elevation ecosystems are characterized by unique environmental conditions, which establish correspondingly unique niches for microorganisms, including protosteloid amoebae – unicellular protists with key roles in organic matter decomposition and nutrient cycling. This study primarily assessed the diversity and occurrences of protosteloid amoebae on a remote mountainous range with varying elevations. Field sampling was conducted across several sites, and organic debris and litter were collected, returned to the laboratory and placed on primary isolation plates. In total, 13 species of protosteloid amoebae and protosteloid-like organisms were observed. These belong to 11 genera, with distinct species including Ceratiomyxella tahitiensis sp. complex, Echinosteliopsis oligospora, Schizoplasmodium cavostelioides, Soliformovum irregulare, and Protosteliopsis fimicola. However, community analyses revealed no significant differences compared to the lowland areas and revealed close similarities among the sampling sites. The findings of this study provide additional in-formation on the existing microbial diversity in the mountainous ranges with a tropical semi-temperate climate, which has implications for their biogeographical patterns and distribution.
In the present study, a new species of septate gregarine, inhabiting Brachythemis contaminata Fabricius, 1793, a common drag-mass variablesresulting in the foll wingstatsticallyignificant equation (p = 003): Aonfly species in West Bengal, India, was identified and characterised. Mature trophozoites are solitary and pyriform. The epimerite complex extends up to 112 mu m in length and includes a terminal, hat-shaped epimerite proper with 8-12 distinct, very deeply ovoid to narrowly terococcus concentration(number/ml). In general, given the ncreasingevidence of the potential importance of amoeboid protistsn aquatic ovoid petals without pointed apices and an oblong diamerite. Gamonts are isogamontic and also pyriform (similar to 230 x 167 mu m), with a broadly obpanduriform protomerite and a pyriform deutomerite. Gametocysts are more or less orbicular (similar to 345 mu m). Under SEM, both trophozoites and gamonts are found to be covered by longitudinal, undulating epicytic folds, except epimerite proper. An orbicular, retracted area with a central, roughly orbicular region devoid of epicytic folds is present at the anterior end of the gamont, measuring 24.7-40.6 mu m in diameter. Key words: Aquatic ecosystems,eukaryotic micr bial communities climate effects, microbiaheterotrophic food webs microbial Tetrahedral configuration of the oocysts is prominent, characterised by a smooth surface and terminalprojections with an apical, sucker-like structure. The above characteristics align this septate gregarine with the genus Odonaticola. The distinctive morphological traits, including pyriform trophozoites and gamonts and an epimerite proper with 8-12 distinct, ovoid petals without pointed apices, support its erection as a new species, Odonaticola pyriforma n. sp.
Silicoflagellates are a poorly documented component of marine phytoplankton along the Moroccan Atlantic coast of North Africa Although rarely encountered in plankton samples, they can provide valuable insights into water column dynamics and upwelling regimes. This study aimed to characterize the taxonomic composition and morphological variability of silicoflagellates in two contrasting coastal environments influenced by seasonal upwelling: El Jadida Bay and Oualidia Lagoon. In El Jadida Bay, a relatively diverse assemblage was observed, including Dictyocha epiodon Ehrenberg, an unusual morphotype of Dictyocha cf. fibula, several morphotypes of Octactis pulchra Schiller, and Stephanocha speculum (Ehrenberg) McCartney and Jordan. In contrast, the lagoon assemblage was less diverse, with only three taxa recorded: Dictyocha fibula Ehrenberg, D. fibula var. robusta Schrader and Murray, and Stephanocha speculum, the only species shared between both habitats. In addition to morphological analysis, selected environmental variables were assessed, and chemical element data from Oualidia Lagoon (Chaouite et al. 2018) were reintegrated to contextualize species distribution and potential environmental stressors. Data analysis was performed with the R software (version 4.3.1), using packages from the tidyverse (including tidyr and ggplot2), cowplot, fmsb, and Venn diagram.
The present study provides a detailed redescription of the very little-known oxytrichid ciliate, Cyrtohymena torrenticola, collected from Baiyangdian Lake in northern China. The morphology of the Chinese population agrees very well with the original description, including a slender, Urosoma-like body outline, a cyrtohymenid oral apparatus, and terminally arranged transverse cirri. In addition, our study shows that C. torrenticola has (i) six dorsal kineties and (ii) yellowish, about 1 µm-sized cortical granules. An improved diagnosis is provided. From four dividers we can conclude (i) that the oral primordium originates de novo, (ii) that all postoral ventral cirri are involved in primordia formation, (iii) that the anlagen V and VI of both proter and opisthe, very likely originate via primary primordia, and (iv) that the dorsal ciliature is formed in the Oxytricha pattern, that is, kinety 3 fragments to form kinety 4 and two dorsomarginal kineties originate from/near the right marginal row anlagen. A phylogeny using SSU rDNA sequence data basically supports the morphological classification in Cyrtohymena. Both the type locality and our record strongly indicate that C. torrenticola prefers limnetic habitats. Our population cannot be used for neotypification because it was collected far away from the type locality.
Protosteloid from the deciduous marsh grass produced organic matterinthe sediment surface,the meanabundance of active amoebae +/- standarderro Abstract. Protosteloid amoebae are a group of fungus-like protists that play critical ecological roles in nutrient cycling and microbial reguof the mean(SEM)washigher (3.07 +/- 0 99 x 104/ L,N 7).nwarmer months (MaytoSeptmber) the abundance of amoebae waslower lation within terrestrial ecosystems. Despite their ecological importance, their diversity and spatial distribution in Philippine landscapes (1.35 +/- 029 x 104 / LN 1 ).Amultivariate linear regresion analysis wasperformed relatingamoeba abundancet four major waer remains understudied. Hence, this study randomly collected foliar litter on five timber upland forests and five coastal lowland forests to mass variables, resulting inthefollowingstatisticallysignificant equation (p 0.03): AD = 0.121 x T + 0.301 x L 0047 x S + 0 359 x C, capture the range of microhabitats that may influence protosteloid diversity and investigate the spatial distribution of protosteloid amoebae where AD=active amoebae densty(x 104/L),T temperatureA( C), Ltde evel(m), S = Secchi disc depth (cm) and C bacterial en-across a ridge-to-reef ecosystem in San Fernando City, La Union, Philippines. Using established laboratory protocols and morphological terococcus c ncentration (number/ml) In general given the increasngevidence ofthe potential importance of amoeboid protists n aquatic examination, the following results were revealed: (i) eleven determinable species belonging to seven genera reflected a moderate sampling ecosystems,further research is warrantedon their role in food webs andthe carbon biogeochemical cycle within heterotrophic estuarine effort for the study, (ii) species diversity of protosteloid amoebae was higher in the upland than in the lowland but almost the same when and coastal waters. microhabitats (aerial vs ground) were compared, and (iii) there were more similarities in composition in terms of substrates rather than elevation. These findings suggest that the distribution between upland and coastal lowland habitats is affected by possible ecological gradients Keyword : Aquatic ecosystems,eukaryotic microbial communites, climate effects,microbial heterotrophic food webs, microbal and habitat specificity playing a vital role in shaping protist communities. This study highlights the urgent need for management strategies productiviy. to protect unique microhabitats along the Philippine ridge-to-reef ecosystems and preserve the region's hidden microbial biodiversity.
Understanding the physiological and genetic diversity of single-cell eukaryotes remains a big challenge for scientists. Single-cell omics technologies have revolutionized our possibilities for many previously uncharacterized groups. Despite the great advancement, there is still a substantial gap in our genomic knowledge about eukaryotes, with less than 1% of species sequenced. This knowledge gap is even more pronounced in some microbial eukaryote groups such as Arcellinids. Arcellinida is a group of bioindicator protists that inhabit mostly freshwater and soil environments. Currently, we don’t have any genome available for the Arcellinida group, undermining our capacity to understand their biology, metabolic capacities, and resistance mechanisms that makes them useful as bioindicators. Using transcriptomic data only, we made great progress in this group by elucidating, for example, their systematics, sex, and metabolism. This manuscript highlights the potential of Arcellinida as a model for genomic studies, particularly the Arcella uspiensis species. Through comparative analysis, we demonstrate that despite its importance, transcriptomics hinders some limitations that need to be acknowledged. Finally, considering that we have much basic biology knowledge and protocols for Arcella uspiensis, we propose sequencing the genome of this species as a way to unlock further potential insights into ecology, evolution, and function of Arcellinida. This manuscript emphasizes the importance of exploring genomics as a way to understand the ecology and evolution of microbial eukaryotic groups.
Decomposing cadavers have a strong impact on the soil environment and the biodiversity of soil organisms. However, exploring these patterns in different natural settings, and beyond the first few weeks post-mortem remains a research priority. The response of soil communities to decomposing cadavers could be used for estimating the post-mortem interval (PMI), for which current models are lacking beyond 4-6 weeks. We conducted a 35-month field experiment using pig carcasses (Sus scrofa Linnaeus) in a deciduous forest in Switzerland to characterise the impact of decomposing cadavers on the diversity and community composition of soil micro-eukaryotes by high throughput sequencing of soil environmental DNA. The diversity of soil microbial eukaryotes strongly declined under decomposing cadavers. Several taxa which were rare in control soils became more abundant in cadaver-impacted soils. The clear temporal succession and turnover in soil microbial eukaryote diversity and community structure underneath cadavers offers potential for inferring the PMI. The diversity of soil micro-eukaryotes remains poorly documented, especially in under-studied habitats such as cadaver-impacted soils. Characterising this "rare biosphere" diversity will help better understand cadaver impacts on terrestrial ecosystems and is necessary to develop new PMI tools.
Research on testate amoebae goes back to the early 19th century, more precisely the year 1815 when Leclerc (or Le Clerc) described the genus Difflugia , which he presented as a “new type of amorphous polyp” (Leclerc, 1815). Since then the pace of publication was uneven but some very significant early works such as the seminal works of Leidy, Penard, and Cash, Hopkinson and Wailes paved the way to future research (Penard, 1890, Penard, 1902, Penard, 1911, Leidy, 1879, Cash et al., 1905-1921). These early studies focused on describing the diversity of testate amoebae but also included discussions (or speculations) about their geographical distribution and ecology. The lives and scientific careers of Leidy and Penard were nicely described by Corliss who had the privilege of meeting Penard towards the end of his long life (Corliss, 2001).
Per Theodor Cleve is known as a 19th century chemist, credited with discovery of two rare-earth elements. However, throughout his distinguished career as a chemist, he was also a protistologist. From 1863 to 1905, Cleve published prodigiously on protists, authoring over 70 works totaling about 2,500 pages, and he described numerous taxa, especially from the marine plankton. Notably, many of Cleve's works are still cited today. His work concerning the utility of certain protist species in characterizing water masses has been recognized in histories of Oceanography. However, Cleve is not a familiar name to many of us, as he has been consistently overlooked in histories of protistology. Here, first Cleve's life is summarized, and then his contributions to protistology, and oceanography, are reviewed to show his significant, and neglected, contributions to the fields.
Unerstanding the physilogical and genetic diversity of single-cell eukaryotes remains big challenge for scientists. Single-cell from the deciduous marsh grass produced organic matter in the sediment surface the mean abundance of active amoebae +/- standard error mics techologies have revolutionized our possibilities for many previously uncharacerized groups. Despite the great dvancement, there of the mean(SEM) was higher (3 07 +/- 0 99 x 104/ L N = 7) In warmer months (May to September) the abundance of amoebae was lower is still a substantial gap in our genoic knowledge about eukaryotes, with les than 1 % of species sequenced. This knowledge gp is even (1 35 +/- 029 x 104 / L, N = 10) A multivariate linear regression analysis wasperformed relating amoeba abundance to four major water more pronounced in some microbial eukaryote groups such as Arcellinids. Arcellinida is a group of bioindicator protists that inhabit mostly freshwater and soil environments. Currently, we don't have any genome availabl for the Arcellinida group, undermiing our capacity to where: A = active amoebae densty (x 104/L) T = temperature (oC) L = tide level (m) S = Secchi dsc deph (cm) and C = bacterial nunderstand their biology, metabolic capacities, and resistance mechanisms that makes them useful as bioindicators. Using transcriptomic data only, we made great progress in this group by elucidating, for example, thei systematics, sex, and metabolism. This manuscrip highecosystems further research is warranted on their role in food webs and the car bon biogeochemical cycle within heterotrophic est uarine lights the potential of Arcellinida as a model for genomic studies, particularly the Arcella uspiensis species. Through comparative analysis, we demonstrate that despite its importance, transcriptomics hinders some limitations that need to be acknowledged. Finally, considering that w have much basic biology knowledge and protocols for Arcella uspnsis, we propose sequencing the genome of this species as a way to Ke y words:unlock furher potential insights into ecology, evolution, and function of Arcellinida. This manuscript emphasizes the importance of exploring genomics as a way to understand the ecology and evolution of microbial eukaryotic groups.
Despite of the rapid advancements in genomic tools over the past decade, genomic data remains limited for many protists, with some taxonomic groups lacking it entirely. One such group is testate amoebae, a group of shelled amoeboid protists known to have a long fossil record. Indeed, for some of them (i.e., arcellinid testate amoebae) the evolutionary roots trace back approximately 730 million years. Beyond their fascinating evolutionary history, these organisms are highly valued for their diverse applications across various research fields, including paleoecology, environmental monitoring, ecotoxicology, microbial community ecology, endosymbiont studies, and more. Consequently, their genomic data harbors significant potential for yielding crucial insights within the contexts of evolution, ecology, and climate change, while also offering opportunities for exploration from both biotechnological and functional perspectives. This short communication gives an overview of possible research directions for testate amoebae based on molecular data and outlining innovative techniques that have the potential to elevate testate amoebae research to a new next level.
The majority of predatory protists are size-limited. Arcellinida (Amoebozoa) exhibit the remarkable ability to prey upon larger rganisms. Here, we examine the co-evolution of their robust shells and predatory behavior. Tracing back to the emergence of eukaryotes, we explore how early amoebozoan predators adapted their cytoskeletons to master phagocytosis. We speculate that the diversity of shell morphology as we see it in extant Arcellinida might be a direct result to their adaptation to prey on large organisms.
Bryophytes and lichens provide organic nutrients and a moist environment for the development of microbial communities. Ciliates show adaptations to inhabit these biotopes where water availability is crucial, like forming resting cysts under unfavorable conditions. To identify possible drivers of these terrestrial ciliate communities, we analyzed the taxonomic richness and composition in two paths from Iguazú National Park (Circuito Inferior, near waterfalls; Sendero Macuco, away from cascades), during wet and dry periods, in samples composed of bryophytes or bryophytes + lichens growing on trees or rocks. The non-flooded Petri dish and optical microscopy methods were used. A total of 132 ciliates were found, mostly Spirotrichea and Colpodea. Taxonomic richness differed between paths (GLMM, p = 0.05), being 1.4 times higher in Sendero Macuco, which had more exclusive taxa than Circuito Inferior. Likewise, ciliate assemblages were influenced by habitat conditions and sample composition (NMDS, ANOSIM test p < 0.01). Bryophytes and lichens were dampened by the waterfall’s spray in Circuito Inferior during the wet period when higher richness was observed. In Sendero Macuco, higher richness occurred during the dry period, suggesting these differences could be related to contrasting habitats instead of climatic conditions. Nevertheless, C/P indices revealed a prevalence of the r-selected Colpodea over the K-selected Spirotrichea + Heterotrichea in both paths during the dry period, indicating unstable environmental conditions. Further research is needed to deepen our knowledge on terrestrial ciliates in this natural protected area from South America, which is a world hotspot for biodiversity.
We recently documented the existence of 26 different forms of Papulifères, presumptive ciliate cysts, from plankton net tow material of the Chukchi Sea gathered in 2015, 2021, and 2022. The forms appeared to be rare, found in only 7 of the 308 samples taken in annual August surveys from 2010 to 2022. Thus, we were surprised to find them relatively common and widespread in samples gathered in August of 2023. We found 18 different Papulifére forms, 8 of which appear to be new forms, in samples from 19 of the 36 stations sampled. They were found in localities ranging from 70.5°N to 80°N. Here we report on these Papulifére forms found in 2023, providing information on morphologies and geographical distributions. With this report we have expanded the catalogue of observed Papulifére, and photographed, forms of the Chukchi Sea to a grand total of 34 of morphologically distinct forms. However, we continue to urge caution in assigning a ciliate identity to any given Papulifére form in the absence of corroborating data.
FOP is a centriole satellite protein involved in ciliogenesis. Although centriole satellites are involved in centrosome and ciliumrelated protein trafficking, their functions related to ciliary assembly and maintenance of ciliary microtubule stability remain unclear. In this study, the function of the FOP gene in Euplotes amieti was investigated by interfering with its expression using RNAi. As a result, expression levels of the ciliary assembly-related proteins BBS8 and IFT88 were down-regulated. Swimming speeds also decreased and the Euplotes were only able to spin in circles, which suggested that the FOP protein is an important protein involved in ciliary motion. Further observations of Euplotes amieti microstructure and ultrastructure via immunofluorescence and transmission electron microscopy revealed that FOP not only participated in the formation of the ventral ciliary basal body but also played an important role in the maintenance of cortical microtubules, which is fundamental for the morphological structure of Euplotes amieti.
Most eukaryotic microbial biodiversity is undescribed, and most species might be morphologically indistinguishable. Notable exceptions are so-called flagship species which are highly conspicuous and can therefore be used to address biogeographical questions. Here we describe Hyalosphenia papilio subsp. paynei, an arcellinid testate amoeba (Amoebozoa; Arcellinida; Hyalospheniidae) from wet hollows in two Sphagnum peatlands, one in Wales and one in Ireland. Phylogenetic analysis based on Cytochrome Coxidase subunit I (COI) sequencing places it within the lineage A of the H. papilio complex, but it differs from all 13 known H. papilio genetic lineages by its very distinctive, wider than long, morphology. The fact that such a conspicuous taxon was never reported in hundreds of studies published on Holarctic Sphagnum peatlands since Leidy’s description of H. papilio in 1874 suggests that this subspecies has not dispersed and survived beyond Britain and Ireland. Furthermore its genetic similarity to H. papilio s. str. suggests that it has recently evolved. The discovery of this new taxon calls for a more detailed analysis of the morphological, ecological and molecular diversity of the H. papilio species complex.
