Biology subjects

Vaulot, D.

Publications and source records attributed to Vaulot, D..

18 recordsLinked to original sources

bioRxiv2026

Labyrinthula merlionensis sp. nov.: a novel labyrinthulid infecting marine diatoms

Labyrinthulomycetes are a class of fungus-like heterotrophic protists from the Stramenopiles lineage, recognized for their ecological role as decomposers and contributors to nutrient cycling. They colonize various substrates, from seaweed to terrestrial environments, utilizing ectoplasmic networks for nutrient absorption. This study characterized a novel Labyrinthula strain associated with the marine diatom Biddulphia. Phylogenetic analysis of the full-length 18S rRNA gene positioned this strain as a new species, Labyrinthula merlionensis sp. nov. Scanning electron and light microscopy observations revealed bi-flagellated zoospores and spindle-shaped vegetative cells with ectoplasmic networks. Time-series observations of the interactions between L. merlionensis and Biddulphia were categorised into different phases: establishment, infection, and aggregation. Scanning electron and confocal microscopy observations during the infection phase established the use of ectoplasmic nets to target the marginal ridge regions between diatoms, and the detection of labyrinthulid cells within diatom frustules. These findings enhance the understanding of the diversity, morphology, and ecological roles of Labyrinthulomycetes, particularly their intra- and extra-cellular interactions with diatom hosts.

ecology↗

bioRxiv2025

Evaluating 18S Phylogenetic Placement Accuracy to Uncover Hidden Diversity in Early Branching Animals

Small subunit ribosomal RNA (SSU rRNA) - 18S in eukaryotes - is a gene universally present across the Tree of Life and it was central in resolving ancient relationships in early molecular phylogenies. Nowadays, despite multi-locus phylogenomic approaches dominate, SSU rRNA sequences still serv as a molecular identifier of biodiversity. Phylogenetic placement uses a reference phylogeny and a given evolutionary model to annotate taxonomically environmental DNA. As such, it enables more accurate identification of divergent sequences that may belong to unknown lineages across the Tree of Life. Here we first created the largest dataset of 18S sequences belonging to non-Bilateria metazoans, by curating the sequences found in PR2 database. We then used it as a case study to test the performance of different 18S-based barcodes (V4, V9, and full-length 18S) within a phylogenetic placement framework. Employing a series of sensitivity analyses, we found that the V9 region generally lacks sufficient phylogenetic signal for reliable placements in most of the cases. The V4 region is accurate when the environmental diversity is well represented in the reference tree but struggles with divergent lineages. Full-length 18S overcome short-read limitations and emerges as the most robust option to uncover unknown major clades. Finally, we apply phylogenetic placement to empirical environmental 18S data. We observe geographical variation in non-bilaterians communities and recover a putative clade of early-branching Ctenophora based on long-sequence barcodes.

evolutionary biology↗

bioRxiv2024

A Novel Taxonomic Database for eukaryotic Mitochondrial Cytochrome Oxidase subunit I Gene (eKOI): Enhancing taxonomic resolution at community-level in metabarcoding analyses

Metabarcoding has emerged as a robust method for understanding biodiversity patterns by retrieving environmental DNA (eDNA) directly from ecosystems. Its low cost and accessibility have extended its use across biological topics, from symbiosis to biogeography, and ecology. A successful metabarcoding application depends on accurate and comprehensive reference databases for proper taxonomic assignment. The 18S rRNA gene is the primary genetic marker used for general/broad eukaryotic metabarcoding due to its combination of conserved and hypervariable regions, and the availability of extensive taxonomically-informed reference databases like PR2 and SILVA. Despite its advantages, 18S rRNA has certain limitations at lower taxonomic levels, depending on the lineage. Alternative fast-evolving molecular markers, such as the mitochondrial cytochrome oxidase subunit I (COI) gene, have been adopted as widely used "barcoding genes" for eukaryotes due to their resolution to the species level. However, the COI gene lacks a curated taxonomically-informed database covering all eukaryotes, including protists, comparable to those available for 18S rRNA. To address this gap, we introduce eKOI, a curated COI gene database aimed at enhancing the taxonomic annotation and primer design for COI-based metabarcoding at the community level. This database integrates COI gene data from GenBank and mitochondrial genomes that are publicly available, followed by rigorous manual curation to eliminate redundancies and contaminants and to correct taxonomic annotations. We validate using the eKOI database for taxonomic annotation of protists by re-annotating several COI-based metabarcoding studies, revealing previously unidentified biodiversity. Phylogenetic analyses confirmed the accuracy of the taxonomic annotations, highlighting the potential of eKOI to uncover new biodiversity in various eukaryotic lineages.

ecology↗

bioRxiv2024

Temporal dynamics and biogeography of sympagic and planktonic autotrophic microbial eukaryotes during the under-ice Arctic bloom

Photosynthetic microbial eukaryotes play a pivotal role as primary producers in the Arctic Ocean, where seasonal blooms within and below the ice are crucial phenomena, contributing significantly to global primary production and biogeochemical cycling. In this study, we investigated the taxonomic composition of sympagic algae and phytoplankton communities during the Arctic under-ice spring bloom using metabarcoding of the 18S rRNA gene. Samples were obtained from three size fractions over a period of nearly three months at an ice camp deployed on landfast ice off the coast of Baffin Island as part of the Green Edge project. We classified the major sympagic and phytoplankton taxa found in this study into biogeographical categories using publicly available metabarcoding data from more than 2 800 oceanic and coastal marine samples. This study demonstrated the temporal succession of taxonomic groups during the development of the under-ice bloom, illustrated by an overall transition from polar to polar-temperate taxa, in particular in the smallest size fraction. Overlooked classes such as Pelagophyceae (undescribed Pelagomonadales clade A1 and the genus Ankylochrysis), Bolidophyceae (Parmales environmental clade 2), and Cryptophyceae (Baffinella frigidus) might play a greater role than anticipated within the pico-sized communities in and under the ice pack during the pre-bloom period. Finally, we emphasize the importance of microdiversity, taking the example of B. frigidus for which a new strain isolated during Green Edge represents an ice ecotype while the type strain is clearly linked to marine waters.

ecology↗

bioRxiv2024

The community of Marine Alveolate parasites in the Atlantic inflow to the Arctic Ocean is structured by season, depth and water mass

The marine alveolates (MALVs) are a highly diverse group of parasitic dinoflagellates, which may regulate populations of a wide range of hosts, including other dinoflagellates, copepods and fish eggs. Knowledge on their distribution and ecological role is still limited, as they are difficult to study with morphological methods. In this work, we describe the taxonomic composition, seasonal- and depth distribution of MALVs in the Arctic Ocean west and north of Svalbard, based on metabarcoding data from five cruises. We recovered amplicon sequence variants (ASVs) representing all major groups previously described from environmental sequencing studies (Dino-Groups I-V), with Dino-Groups I and II being the most diverse. The community was structured by season, depth, and water mass. In the epipelagic zone, the taxonomic composition varied strongly by season, however there was also a difference between Arctic and Atlantic water masses in winter. The spring and summer epipelagic communities were characterized by a few dominating ASVs, which were present in low proportions during winter and in mesopelagic summer samples, suggesting that they proliferate under certain conditions, e.g., when specific hosts are abundant. The mesopelagic samples were more similar across sampling months, and may harbor parasites of deep-dwelling organisms, little affected by season.

ecology↗

bioRxiv2022

Arctic phytoplankton spring bloom diversity across the marginal ice zone in Baffin Bay

Phytoplankton under-ice blooms have been recently recognized as an important Arctic phenomenon for global primary production and biogeochemical cycling. Drastic sea-ice decline in both extension and thickness enables the development of early blooms, sometimes hundreds of kilometers beneath the pack ice. Baffin Bay is a semi-enclosed sea where Arctic and North Atlantic water masses interact. It is totally covered by sea-ice by March and ice-free by August/September. In the present work, we investigated the phytoplankton community structure across the marginal ice zone between the ice-free, Atlantic-influenced, east and the ice-covered, Arctic-influenced, west Baffin Bay using 18S rRNA high-throughput amplicon sequencing, flow cytometry cell counting and numerous environmental and biological data collected and compiled in the scope of the Green Edge project. Sampling was performed during June-July 2016 in a total of 16 stations with around 6 depths each. Stations were clustered into "Under Ice" (UI), "Marginal Ice Zone" (MIZ) and "Open Water" (OW) on the basis of its sea ice cover upon sampling. Phytoplankton community structure was analyzed by 18S rRNA metabarcoding with the microdiversity approach. The UI sector was characterized by a shallow nitracline, high pico-phytoplankton abundance and a shared dominance between Micromonas and Phaeocystis in the 0.2-3 {micro}m size fraction, as well as an increased contribution of Cryptophyceae and non-diatom Ochrophyta in the 3-20 {micro}m size fraction. Several amplicon sequence variants (ASVs) were flagged as indicator for the UI+MIZ sector group, including known ice-associated taxa such as the diatoms Melosira arctica and Pseudo-nitzschia seriata, but also specific ASVs assigned to the green alga Micromonas polaris and the cryptophyte Falcomonas daucoides, the silicoflagellate Dictyocha speculum, one member of the uncultivated MOCH-2 group, and a Pterosperma sp. (green algae) rarely seen in other metabarcoding datasets, including from the Arctic. The OW sector harbored a community adapted to a nutrient-depleted/high light environment, with a significant contribution of the haptophytePhaeocystis pouchetii and big centric diatoms, including several Thalassiosira species.

microbiology↗

bioRxiv2022

metaPR2: a database of eukaryotic 18S rRNA metabarcodes with an emphasis on protists.

In recent years, metabarcoding has become the method of choice for investigating the composition and assembly of microbial eukaryotic communities, and an increasing number of environmental datasets are being published. Although unprocessed sequence files are often publicly available, processed data, i.e. sequences clustered as operational taxonomic units (OTUs) or amplicon sequence variants (ASVs) are rarely at hand in a comparable format. This hampers comparative studies between different environments and datasets, for example examining the biogeographical patterns of specific groups/species, as well analysing the micro-genetic diversity within these groups. Here, we present a newly-assembled database of processed 18S rRNA metabarcodes that are annotated with the PR2 reference sequence database. This database, called metaPR2, contains 41 datasets corresponding to more than 4,000 samples and 73,000 ASVs. The database is accessible through both a web-based interface (https://shiny.metapr2.org) and as an R package, and should prove very useful to all researchers working on protist diversity in a variety of systems.

ecology↗

bioRxiv2021

Global patterns and rates of habitat transitions across the eukaryotic tree of life

The successful colonisation of new habitats has played a fundamental role during the evolution of life. Salinity is one of the strongest barriers for organisms to cross, which has resulted in the evolution of distinct marine and terrestrial (including both freshwater and soil) communities. Although microbes represent by far the vast majority of eukaryote diversity, the role of the salt barrier in shaping the diversity across the eukaryotic tree is poorly known. Traditional views suggest rare and ancient marine-terrestrial transitions, but this view is being challenged by the discovery of several recently transitioned lineages. Here, we investigate habitat evolution across the tree of eukaryotes using a unique set of taxon-rich environmental phylogenies inferred from a combination of long-read and short-read metabarcoding data spanning the ribosomal DNA operon. Our results show that overall marine and terrestrial microbial communities are phylogenetically distinct, but transitions have occurred in both directions in almost all major eukaryotic lineages, with at least 350 transition events detected. Some groups have experienced relatively high rates of transitions, most notably fungi for which crossing the salt barrier has most likely been an important aspect of their successful diversification. At the deepest phylogenetic levels, ancestral habitat reconstruction analyses suggest that eukaryotes may have first evolved in non-saline habitats, and that the two largest known eukaryotic assemblages (TSAR and Amorphea) arose in different habitats. Overall, our findings indicate that crossing the salt barrier has played an important role in eukaryotic evolution by providing new ecological niches to fill.

evolutionary biology↗

bioRxiv2021

An 18S V4 rDNA metabarcoding dataset of protist diversity in the Atlantic inflow to the Arctic Ocean, through the year and down to 1000 m depth.

Arctic marine protist communities have been understudied due to challenging sampling conditions, in particular during winter and in deep waters. The aim of this study was to improve our knowledge on Arctic protist diversity through the year, both in the epipelagic (< 200 m depth) and mesopelagic zones (200-1000 m depth). Sampling campaigns were performed in 2014, during five different months, to capture the various phases of the Arctic primary production: January (winter), March (pre-bloom), May (spring bloom), August (post-bloom) and November (early winter). The cruises were undertaken west and north of the Svalbard archipelago, where warmer Atlantic waters from the West Spitsbergen Current meets cold Arctic waters from the Arctic Ocean. From each cruise, station, and depth, 50 L of sea water were collected and the plankton was size-fractionated by serial filtration into four size fractions between 0.45-200 {micro}m, representing the picoplankton, nanoplankton and microplankton. In addition vertical net hauls were taken from 50 m depth to the surface at selected stations. From the plankton samples DNA was extracted, the V4 region of the 18S rRNA-gene was amplified by PCR with universal eukaryote primers and the amplicons were sequenced by Illumina high-throughput sequencing. Sequences were clustered into Amplicon Sequence Variants (ASVs), representing protist genotypes, with the dada2 pipeline. Taxonomic classification was made against the curated Protist Ribosomal Reference database (PR2). Altogether 6,536 protist ASVs were obtained (including 54 fungal ASVs). Both ASV richness and taxonomic composition were strongly dependent on size-fraction, season, and depth. ASV richness was generally higher in the smaller fractions, and higher in winter and the mesopelagic samples than in samples from the well-lit epipelagic zone during summer. During spring and summer, the phytoplankton groups diatoms, chlorophytes and haptophytes dominated in the epipelagic zone. Parasitic and heterotrophic groups such as Syndiniales and certain dinoflagel-lates dominated in the mesopelagic zone all year, as well as in the epipelagic zone during the winter. The dataset is available at https://doi.org/10.17882/79823, (Egge et al., 2014).

ecology↗

bioRxiv2021

pr2-primers: an 18S rRNA primer database for protists

Metabarcoding of microbial eukaryotes (collectively known as protists) has developed tremendously in the last decade, almost uniquely relying on the 18S rRNA gene. As microbial eukaryotes are extremely diverse, many primers and primer pairs have been developed. To cover a relevant and representative fraction of the protist community in a given study system, a wise primer choice is needed as no primer pair can target all protists equally well. As such, a smart primer choice is very difficult even for experts and there are very few on-line resources available to list existing primers. We built a database listing 179 primers and 76 primer pairs that have been used for eukaryotic 18S rRNA metabarcoding. In silico performance of primer pairs was tested against two sequence databases: PR2 for eukaryotes and a subset of Silva for prokaryotes. This allowed to determine the taxonomic specificity of primer pairs, the location of mismatches as well as amplicon size. We developed a R-based web application that allows to browse the database, visualize the taxonomic distribution of the amplified sequences with the number of mismatches, and to test any user-defined primer set (https://app.pr2-primers.org). This tool will provide the basis for guided primer choices that will help a wide range of ecologists to implement protists as part of their investigations.

ecology↗

bioRxiv2020

Annual phytoplankton dynamics in coastal waters from Fildes Bay, Western Antarctic Peninsula.

Year-round reports of phytoplankton dynamics in the West Antarctic Peninsula are rare and mainly limited to microscopy and/or pigment-based studies. We analyzed the phytoplankton community from coastal waters of Fildes Bay in the West Antarctic Peninsula between January 2014 and 2015 using metabarcoding of the nuclear and plastidial 18/16S rRNA gene from both size-fractionated and flow cytometry sorted samples. Each metabarcoding approach yielded a different image of the phytoplankton community with for example Prymnesiophyceae more prevalent in plastidial metabarcodes and Mamiellophyceae in nuclear ones. Overall 14 classes of photosynthetic eukaryotes were present in our samples with the following dominating: Bacillariophyta (diatoms), Pelagophyceae and Dictyochophyceae for division Ochrophyta, Mamiellophyceae and Pyramimonadophyceae for division Chlorophyta, Prymnesiophyceae and Cryptophyceae. Diatoms were dominant in the larger size fractions and during summer, while Prymnesiophyceae and Cryptophyceae were dominant in colder seasons. Pelagophyceae were particularly abundant towards the end of autumn (May). In addition of Micromonas polaris and Micromonas sp. clade B3, both previously reported in Arctic waters, we detected a new Micromonas 18S rRNA sequence signature, close to but clearly distinct from M. polaris, which potentially represent a new clade specific of the Antarctic. These results highlight the need for complementary strategies as well as the importance of year-round monitoring for a comprehensive description of phytoplankton communities in Antarctic coastal waters.

ecology↗

bioRxiv2020

No evidence of phago-mixotropy in Micromonas polaris, the dominant picophytoplankton species in the Arctic

In the Arctic Ocean, the small green alga Micromonas polaris dominates pico-phytoplankton during the summer months. It has been previously hypothesized to be phago-mixotrophic (capable of bacteria ingestion) based on laboratory and field experiments. Prey uptake was analysed in several M. polaris strains isolated from different regions and depths of the Arctic Ocean. Using both fluorescent beads and fluorescently labelled bacteria as prey, we found no evidence of phago-mixotrophy in any M. polaris strain by flow cytometric measurement of prey ingestion. In addition, in silico predictions reveal that members of the genus Micromonas lack a genetic signature of phagocytotic capacity.

ecology↗

bioRxiv2020

Taxonomic reassignment of Pseudohaptolina birgeri comb. nov. (Haptophyta)

The haptophyte genus Pseudohaptolina (formerly Chrysochromulina clade B1-3) currently harbors two species: Pseudohaptolina arctica and Pseudohap-tolina sorokinii. In addition, Chrysochromulina birgeri is expected to belong to this genus due to its morphological similarity to P. sorokinii, but has not yet been genetically characterized. A strain belonging to Pseudohaptolina was brought into culture from Arctic waters, characterized by 18S and 28S rRNA gene sequencing as well as optical and transmission electron microscopy, and deposited in the Roscoff Culture Collection with the code RCC5270. Molecular and morphological data from RCC5270 were compared with those from previously described Pseudohaptolina and Pseudohaptolina-like species. Strain RCC5270 showed strong phylogenetic affinity to P. sorokinii, but TEM observations showed that RCC5270 possesses three types of organic body scale, rather than two as originally described in P. sorokinii. We found that the occurrence of three scale types is likely to have been overlooked in the original descriptions of both P. sorokinii and C. birgeri. We also found that environmental metabarcodes identical to the sequence of RCC5270 were abundant in the location from which C. birgeri was initially described (Gulf of Finland). We conclude that P. sorokinii and C. birgeri are conspecific and P. sorokinii is therefore synonymous with C. birgeri. Based on its phylogenetic placement and nomenclatural priority we propose the new combination Pseudohaptolina birgeri and emend the description of this species.

microbiology↗

bioRxiv2019

A user guide to environmental protistology: primers, metabarcoding, sequencing, and analyses

Protists - all eukaryotes besides fungi, animals, and plants - represent a major part of the taxonomic and functional diversity of eukaryotic life on the planet and drive many ecosystem processes. However, knowledge of protist communities and their diversity lags behind that of most other groups of organisms, largely due to methodological constraints. While protist communities differ markedly between habitats and biomes, they can be studied in very similar ways. Here we provide a guide to current molecular approaches used for studying protist diversity, with a particular focus on amplicon-based high-throughput sequencing (metabarcoding). We highlight that the choice of suitable primers artificially alters community profiles observed in metabarcoding studies. While there are no true universal primers to target all protist taxa as a whole, we identify some primer combinations with a wide taxonomic coverage and provide detailed information on their properties. Although environmental protistan ecological research will probably shift towards PCR-free metagenomics or/and transcriptomic approaches in a near future, metabarcoding will remain the method of choice for in-depth community analyses and taxon inventories in biodiversity surveys and ecological studies, due its great cost-efficiency, sensitivity, and throughput. In this paper we provide a guide for scientists from a broad range of disciplines to implement protists in their ecological analyses.

microbiology↗

bioRxiv2019

Temporal dynamics of Bacteria, Archaea and protists in equatorial coastal waters

Singapore, an equatorial island in South East Asia, is influenced by a bi-annual reversal of wind directions which defines two monsoon seasons. We characterized the dynamics of the microbial communities of Singapore coastal waters by collecting monthly samples between February 2017 and July 2018 at four sites located across two straits with different trophic status, and sequencing the V6-V8 region of the small sub-unit ribosomal RNA gene (rRNA gene) of Bacteria, Archaea, and Eukaryota. Johor Strait, which is subjected to wider environmental fluctuations from anthropogenic activities, presented a higher abundance of copiotrophic microbes, including Cellvibrionales and Rhodobacterales. The mesotrophic Singapore Strait, where the seasonal variability is caused by changes in the oceanographic conditions, harboured a higher proportion of typically marine microbe groups such as Synechococcales, Nitrosupumilales, SAR11, SAR86, Marine Group II Archaea and Radiolaria. In addition, we observed seasonal variability of the microbial communities in the Singapore Strait, which was possibly influenced by the alternating monsoon regime, while no seasonal pattern was detected in the Johor Strait.

microbiology↗

bioRxiv2019

Culturable diversity of Arctic phytoplankton during pack ice melting

Massive phytoplankton blooms develop at the Arctic ice edge, sometimes extending far under the pack ice. An extensive culturing effort was conducted before and during a phytoplankton bloom in Baffin Bay between April and July 2016. Different isolation strategies were applied, including flow cytometry cell sorting, manual single cell pipetting and serial dilution. Although all three techniques yielded the most common organisms, each technique retrieved specific taxa, highlighting the importance of using several methods to maximize the number and diversity of isolated strains. More than 1,000 cultures were obtained, characterized by 18S rRNA sequencing and optical microscopy and de-replicated to a subset of 276 strains presented in this work. Strains grouped into 57 genotypes defined by 100% 18S rRNA sequence similarity. These genotypes spread across five divisions: Heterokontophyta, Chlorophyta, Cryptophyta, Haptophyta and Dinophyta. Diatoms were the most abundant group (193 strains), mostly represented by the genera Chaetoceros and Attheya. The genera Rhodomonas and Pyramimonas were the most abundant non-diatom nanoplankton strains, while Micromonas polaris dominated the picoplankton. Diversity at the class level was higher during the peak of the bloom. Potentially new species were isolated, in particular within the genera Navicula, Nitzschia, Coscinodiscus, Thalassiosira, Pyramimonas, Mantoniella and Isochrysis.\n\nSubmitted to: Elementa: Science of the Anthropocene Date: May 17, 2019

ecology↗

bioRxiv2018

Mantoniella beaufortii and Mantoniella baffinensis sp. now. (Mamiellales, Mamiellophyceae), two new green algal species from the high Arctic

Members of the class Mamiellophyceae comprise species that can dominate picophytoplankton diversity in polar waters. Yet polar species are often morphologically indistinguishable from temperate species, although clearly separated by molecular features. Here we examine four Mamiellophyceae strains from the Canadian Arctic. The 18S rRNA and Internal Transcribed Spacer 2 (ITS2) gene phylogeny place these strains within the family Mamiellaceae (Mamiellales, Mamiellophyceae) in two separate clades of the genus Mantoniella. ITS2 synapomorphies support their placement as two new species, Mantoniella beaufortii and Mantoniella baffinensis. Both species have round green cells with diameter between 3-5 m, one long flagellum and a short reduced flagellum (~1 m) and are covered by spiderweb-like scales, making both species similar to other Mantoniella species. Morphologically, M. beaufortii and M. baffinensis are most similar to the cosmopolitan M. squamata with only minor differences in scale structure distinguishing them. Screening of global marine metabarcoding datasets indicates M. beaufortii has only been recorded in seawater and sea ice samples from the Arctic while no environmental barcode matches M. baffinensis. Like other Mamiellophyceae genera that have distinct polar and temperate species, the polar distribution of these new species suggests they are cold or ice-adapted Mantoniella species.

microbiology↗

bioRxiv2018

Novel diversity within marine Mamiellophyceae (Chlorophyta) unveiled by metabarcoding

The Ocean Sampling Day (OSD) project provided metabarcoding data for the V4 hyper-variable regions of the 18S rRNA gene from 157 samples collected at 143 mostly coastal stations. In this paper we focus on the class Mamiellophyceae, which was found at nearly all OSD stations and represented 55 % of the green microalgae (Chlorophyta) reads in the 2014 OSD dataset. We performed phylogenetic analyses of unique OSD metabarcodes (ASV, amplicon single variants) and reference GenBank sequences from cultures and from the environment, focusing on the four most represented genera: Ostreococcus (45 % of the Mamiellophyceae reads), Micromonas (34 %), Bathycoccus (10 %) and Mantoniella (8.7 %). These analyses uncovered novel diversity within each genus except Bathycoccus. In Ostreococcus, a new clade (E) with 2 very clear base pair differences compared to the oceanic clade B in the V4 region was the second most represented clade after the coastal Ostreococcus \"lucimarinus\". Within Micromonas, ten clades were found exceeding the 4 species and 2 candidate species already described. Finally, we found 2 new environmental clades of Mantoniella. Each Mamiellophyceae clade had a specific distribution in the OSD dataset suggesting that they are adapted to different ecological niches.

microbiology↗