Journal Of Phycology[JOURNAL]
Sun
200 papers
Nanoscale phycology.
Mann DG
J Phycol · 2025 Dec · PMID 41422388 · Publisher ↗
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When chemistry meets taxonomy: Studying glycolipidic chemomarkers in pelagic Sargassum spp. (Phaeophyceae) using molecular networking.
Nirma C, Stiger-Pouvreau V, Levasseur M … +3 more , Touboul D, Connan S, Petek S
J Phycol · 2026 Feb · PMID 41386632 · Full text
To chemically differentiate the three pelagic Sargassum morphotypes co-occurring in floating rafts and drifting across the Atlantic Ocean before stranding on West African, Caribbean, and Atlantic Mexican coastlines, we c...
To chemically differentiate the three pelagic Sargassum morphotypes co-occurring in floating rafts and drifting across the Atlantic Ocean before stranding on West African, Caribbean, and Atlantic Mexican coastlines, we conducted an investigation of their metabolomic profiles. Hydroethanolic extracts from open-sea raft specimens were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS), and the resulting spectra were processed through feature-based molecular networking with MetGem software. Several glycolipids were putatively identified through spectral matching and manual annotation, predominantly associated with S. natans var. wingei, S. natans var. natans, and S. fluitans var. fluitans. These findings were corroborated by statistical analyses of H NMR spectral fingerprints. This study represents a chemotaxonomic assessment of pelagic Sargassum utilizing molecular networking, demonstrating its efficient utility for putative chemomarker identification. We further discuss the taxonomic status of the three varieties in light of our chemical data, along with observed physiological distinctions among the morphotypes.
A glimpse into darkness: Diversity of culturable cyanobacteria, green algae and fungi from subaerial cave biofilms.
Jung P, Briegel-Williams L, Nürnberg DJ … +4 more , Wolf T, Guillen A, Leira M, Lakatos M
J Phycol · 2025 Dec · PMID 41369050 · Full text
Caves and hypogean environments provide stable microclimates characterized by uniform temperatures, constant humidity, and low light levels. In such sites, extremely low light irradiance can support the growth of subaeri...
Caves and hypogean environments provide stable microclimates characterized by uniform temperatures, constant humidity, and low light levels. In such sites, extremely low light irradiance can support the growth of subaerial biofilms (SABs) dominated by unique photosynthetic communities of cyanobacteria accompanied by chlorophytes, heterotrophic bacteria, and fungi. This study aimed to apply a culture-dependent approach to uncover the diversity of cyanobacteria, green algae, and fungi from SABs of a cave in Northern Spain. We isolated a total of 58 cyanobacteria grouped into 21 genera based on their 16S rRNA gene sequences; 24 green algae grouped into 10 genera based on their SSU rRNA gene sequences, and 41 fungi fell into 13 genera according to phylogenies based on the ITS rRNA region between the 16S and 23S rRNA genes (ITS rRNA region). The SABs were dominated by cyanobacteria, which also reflected by high diversity, including calcium-carbonate sheath-producing species such as Geitleria calcarea and Scytonema julianum. Typical cave-inhabiting species such as Chalicogloea cavernicola, Timaviella karstica or Oculatella subterranea were also isolated, alongside potentially new genera and species. Associated green algae were predominantly located closer to the cave entrance and included various lineages of the genera Jenufa and Chromochloris. The fungal community directly derived from the SABs was dominated by decomposers, saprophytes, and phytoparasitic representatives such as Sporobolomyces, Stereum, and Phlebia, with a corresponding set of enzymes that were evaluated for all fungal isolates. The results strongly support the hypothesis that specialized cyanobacterial communities are often located in caves as a result of niche specialization.
How nitrogen and phosphorus stoichiometry drive the physiology and photosynthesis of Scrippsiella acuminata (Dinophyceae).
Delatte L, Massinot C, Stoltz G … +3 more , Marais F, Hernández-Fariñas T, Claquin P
J Phycol · 2026 Feb · PMID 41351623 · Full text
Development and growth of microalgae are mainly sustained by two essential nutrients: nitrogen (N) and phosphorus (P). Although single-nutrient limitation has been extensively studied, the balance between N and P availab...
Development and growth of microalgae are mainly sustained by two essential nutrients: nitrogen (N) and phosphorus (P). Although single-nutrient limitation has been extensively studied, the balance between N and P availability remains less explored. Scrippsiella acuminata is one of the most abundant dinoflagellates in coastal ecosystems due to its physiological plasticity, making it a key species in the understanding of acclimation to unbalanced nutrient supply. To test the acclimation of S. acuminata, semicontinuous cultures were exposed to six N:P ratios (1.6, 8, 16, 32, 90, 180). Parameters such as photosynthetic response, biovolume, carbon excretion, lipids, reactive oxygen species production, cell cycle, and alkaline phosphatase activity were analyzed. Growth, regular cell cycle progression, balanced carbon allocation carbon resource, and high photosynthesis efficiency occurred at balanced N:P ratios (16, 32). At low ratios (1.6, 8), growth was reduced but cells maintained active photochemistry, whereas high ratios (90, 180) led to an extension of the G1 phase leading to biovolume increase and a limitation of the protective capacity of non-photochemical quenching leading to reactive oxygen species accumulation. Carbon allocation followed a stoichiometric gradient where more limiting N:P ratios favored soluble extracellular polymeric substances and a pool of cellular carbohydrates production as an overflow mechanism to protect cells, whereas moderate limitation led to lipid accumulation as a metabolic reserve. These results not only highlight the plasticity of S. acuminata to acclimate to nutrient stress but also suggest that this species may be more vulnerable in P-limited environments and has a competitive advantage where N is the primary limiting factor.
RNAi reveals a unique set of kinesins mediating chloroplast motility in the giant cytoplasm of Bryopsis (Ulvophyceae), a coenocytic green alga.
Ogawa HA, Ochiai KK, Shirae-Kurabayashi M … +1 more , Goshima G
J Phycol · 2026 Feb · PMID 41351620 · Full text
RNA interference (RNAi) is a powerful tool for protein knockdown and is widely used in model animals and plants. Here, we implemented RNAi in Bryopsis, a green feather alga that develops a coenocytic thallus >10 cm in le...
RNA interference (RNAi) is a powerful tool for protein knockdown and is widely used in model animals and plants. Here, we implemented RNAi in Bryopsis, a green feather alga that develops a coenocytic thallus >10 cm in length without cytokinesis. In vitro-transcribed double-stranded RNA (dsRNA) was either mixed with extruded cytoplasm in the presence of polyethylene glycol and then regenerated into thalli or directly introduced into the cytoplasm by perfusion. Within several days, target-gene transcript levels decreased, and the expected phenotypes emerged, indicating effective RNAi. We designed dsRNAs for all 34 kinesin superfamily genes of a model Bryopsis strain, delivered them by both methods, and monitored chloroplast distribution and motility by microscopy. Knockdown of KCBP-type kinesin-14VI (Kin14VIa and Kin14VIb), which drive retrograde chloroplast transport in the moss Physcomitrium patens, and of the apparently Bryopsis-specific kinesin-14II (Kin14IIb) suppressed retrograde motility, resulting in apical chloroplast accumulation. In addition, RNAi of the Bryopsidales-specific kinesin-14VI (Kin14VIc) reduced both retrograde and anterograde movements, implying that multiple Kin14 motors contribute to chloroplast transport in Bryopsis. In contrast, knockdown of Kin12c, a member of the kinesin-12 family that is known to be essential for cytokinesis in land plants, caused basal chloroplast enrichment, indicating divergent evolution of this motor family in the green lineage. Together, these results establish RNAi as a robust loss-of-function approach in a coenocytic alga and reveal lineage-specific kinesins as key drivers of chloroplast motility within its giant cytoplasm.
Morphomolecular studies of Ceratocorys species (Dinophyceae, Gonyaulacales, Protoceratiaceae) reveal that Ceratocorys armata, C. gourretii, and C. horrida are conspecific and should be considered formae of C. horrida.
Nguyen-Ngoc L, Larsen J, Doan-Nhu H … +12 more , Mertens KN, Lundholm N, Nguyen VX, Krock B, Pham HM, Iwataki M, Plewe S, Bilien G, Dao HV, Huynh-Thi DN, Tran-Thi VL, Probert I
J Phycol · 2025 Dec · PMID 41347297 · Publisher ↗
Ceratocorys armata, C. gourretii, and C. horrida have historically been treated as distinct species based on morphology. Both field samples and cultured strains, however, exhibit continuous morphological variation and in...
Ceratocorys armata, C. gourretii, and C. horrida have historically been treated as distinct species based on morphology. Both field samples and cultured strains, however, exhibit continuous morphological variation and intergradations between these taxa. Here, strains from Viet Nam, Japan (Pacific Ocean), and France (Mediterranean Sea, Atlantic Ocean) were analyzed using integrated morphomolecular approaches. Cultured strains revealed morphological intergradations from C. horrida to C. armata and from C. armata to C. gourretii. Phylogenetic analysis based on the ITS1-5.8S-ITS2 rDNA region sequences and the SSU (18S) and LSU (28S) nuclear rDNA gene sequences confirmed the genetic identity of these three taxa for these markers. The ITS2 secondary structure comparisons-including C. malayensis from Viet Nam and Malaysia-further supported their conspecificity, while validating C. malayensis as a distinct species. Based on these data, we have proposed to treat them as formae: C. horrida f. horrida, C. horrida f. armata, and C. horrida f. gourretii. Furthermore, our results indicated that C. malayensis strains from Viet Nam are non-toxic. We have also provided morphological descriptions and illustrations of C. bipes and C. magna, two species rarely reported in the Asia-Pacific region, enhancing the taxonomic clarity of the genus.
Exogenous methyl jasmonate activates the jasmonic acid signaling pathway in Chlorella sp. to alleviate 2,2',4,4'-tetrabromodiphenyl ether stress.
Bai L, Wang Y, Zhou X … +5 more , Liu Q, Dong L, Che Z, Zhou Z, Wang Y
J Phycol · 2025 Dec · PMID 41342287 · Publisher ↗
Exogenous application of methyl jasmonate (MeJA), a plant stress-responsive hormone, has been suggested to improve plant resistance, but its protective role in marine microalgae under pollutant exposure remains poorly un...
Exogenous application of methyl jasmonate (MeJA), a plant stress-responsive hormone, has been suggested to improve plant resistance, but its protective role in marine microalgae under pollutant exposure remains poorly understood. This study investigated the cytoprotective effects of MeJA on the marine green microalga Chlorella sp. exposed to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a highly biotoxic dibrominated diphenyl ether. Exposure to BDE-47 (0.075 mg · L) significantly impaired cellular structure, inhibited growth, and induced oxidative stress, as evidenced by reactive oxygen species (ROS) overproduction, membrane lipid peroxidation, G2/M phase arrest, and DNA damage. Cotreatment with 0.1 μM MeJA was associated with a significant reduction in adverse effects (p < 0.05), with observed lower ROS levels and elevated activities of key antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). Additionally, MeJA-treated cells exhibited increased endogenous jasmonic acid (JA) content and upregulated lipoxygenase (LOX) activity and allene oxide synthase (AOS) content, both enzymes involved in JA biosynthesis. Partial least squares structural equation modeling suggested a potential link between MeJA-activated JA biosynthesis and antioxidant enzyme induction, indicating a self-amplifying ROS scavenging mechanism that may counteract BDE-47 toxicity. The findings have provided insights into the use of plant hormones to enhance microalgae tolerance to environmental pollutants, with potential applications in microalgae cultivation and biotechnology.
Sphaerochara canadensis (Charophyceae): A circumpolar species with a high temperature optimum.
Böhm J, Blindow I, Gyllenstrand N … +2 more , Diewald W, Schubert H
J Phycol · 2025 Dec · PMID 41334971 · Full text
Sphaerochara canadensis, an aquatic macrophyte belonging to the Characeae, is described as a species with a circumpolar distribution and occurs in the polar (to boreal) zonobiomes, suggesting that it is cold-stenothermic...
Sphaerochara canadensis, an aquatic macrophyte belonging to the Characeae, is described as a species with a circumpolar distribution and occurs in the polar (to boreal) zonobiomes, suggesting that it is cold-stenothermic. A recent report of an occurrence in Lake Wolfgangsee, Austria, contradicted this assumption, prompting this study to investigate the species' physiological adaptation capabilities and, consequently, ability to survive in non-polar environments. Field measurements at Lake Torneträsk, Sweden, indicated that S. canadensis is more adapted to low light compared to the co-occurring charophytes, with water temperatures in the lake ranging from 10 to 12°C during the experiment. Cultivation experiments also revealed clear temperature effects on growth, photosynthetic performance, and pigment composition at 5, 10, 15, and 20°C, with higher temperatures having a positive impact. Furthermore, it was shown that the species can adapt to different light intensities. A published occurrence of the species in Austria is probably erroneous. The photographic material of the original report was misidentified, and eDNA analyses of water samples taken from Lake Wolfgangsee and surrounding water bodies failed to confirm the presence of the species. Consequently, a factor other than temperature limits its distribution. Identifying the factor is crucial for conservation under climate change.
Nutrient-driven regulation of saxitoxin gene expression and toxin production in Raphidiopsis raciborskii (Cyanobacteria).
Zare M, Barçante B, Pimentel JDSM … +1 more , Giani A
J Phycol · 2025 Dec · PMID 41334952 · Full text
Raphidiopsis raciborskii is a diazotrophic cyanobacterium, globally distributed in aquatic environments and known for forming toxic blooms, thereby affecting ecosystem services. South American strains are producers of sa...
Raphidiopsis raciborskii is a diazotrophic cyanobacterium, globally distributed in aquatic environments and known for forming toxic blooms, thereby affecting ecosystem services. South American strains are producers of saxitoxins, potent neurotoxins harmful to humans and animals. This study examined the effect of nutrient availability on saxitoxin production in two toxic R. raciborskii strains. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to investigate the transcriptional response of the saxitoxin sxtA4 gene under nitrogen and phosphorus gradients and the intracellular toxin concentration was measured by high performance liquid chromatography (HPLC). Results showed that the sxtA4 gene expression was generally upregulated at lower nutrient conditions. Positive correlations were observed among transcripts of sxtA4 and genes related to metabolic processes (ntcA, nifH, and pstS), an indication that nutrient stress may affect sxt gene regulation. Intracellular saxitoxin concentration increased slightly under moderate nitrogen reduction (10%), although not always significantly. Under phosphorus reduction, despite the observed upregulated transcription of sxtA4, total saxitoxin concentration significantly decreased, a possible consequence of hindered metabolic fitness. Interestingly, nutrient availability also affected the profiles of toxin analogs produced by R. raciborskii. Because different analogs exhibit variable toxicity, the presence of certain variants may enhance the toxic potential of an entire population under shifting environmental stressors. The responses observed in this study indicate the need for further investigations to identify the mechanisms controlling toxicity. This is particularly relevant as nutrient reduction may control cyanobacterial growth but not necessarily their toxin production.
Stunted canopy: Marine forests under the thermal effluent of a nuclear power plant.
Carneiro IM, Veloso APA, Demarqui FN … +1 more , Széchy MTM
J Phycol · 2025 Dec · PMID 41328748 · Full text
It has been well established that warming beyond certain thresholds can negatively affect the growth of canopy-forming macroalgae. However, most studies evaluating these effects have been conducted under controlled labor...
It has been well established that warming beyond certain thresholds can negatively affect the growth of canopy-forming macroalgae. However, most studies evaluating these effects have been conducted under controlled laboratory conditions. Observational studies investigating the impact of extreme temperatures on growth rates have been rare and typically limited to events such as marine heatwaves or areas affected by thermal pollution. The decline in vertical growth could be detrimental to the development and recovery of macroalgal canopies, significantly impacting habitat complexity. This study examined spatiotemporal variations in thallus height and vertical growth rates of benthic Sargassum species near the Brazilian Nuclear Power Station (BNPS). Samples were collected from sites exposed and unexposed to the thermal effluent of the BNPS, across different periods. Throughout the sampling periods, sites exposed to the thermal effluent consistently exhibited lower vertical growth rates than unexposed sites. Reduced thallus height was also observed at impacted sites during the first sampling period, whereas in the second period, this stunted canopy was observed only at the site closest to the thermal effluent outfall. This decline in vertical growth could reduce habitat complexity, potentially altering the structure of shallow rocky macroalgal communities. Even acknowledging the limitations in establishing cause-effect relationships in in situ studies, these results can provide important insights into the potential effects of warming on shallow, rocky-bottom communities and may offer valuable guidance for managing and monitoring Sargassum populations in the face of thermal pollution and global climate change.
Morphology, phylogeny, and organelle genomics of three new Rhopalodia species (Rhopalodiales, Bacillariophyceae).
Li K, Zhou Y, Chang ACG … +8 more , Amaral MWW, Keepers KG, Nan F, Liu X, Wang J, Xie S, Kociolek JP, Liu Q
J Phycol · 2025 Dec · PMID 41328739 · Publisher ↗
Three new species of the freshwater diatom genus Rhopalodia from Yunnan province, China, have been described in this study based on a combination of morphological and molecular data. The diagnostic characteristics of Rho...
Three new species of the freshwater diatom genus Rhopalodia from Yunnan province, China, have been described in this study based on a combination of morphological and molecular data. The diagnostic characteristics of Rhopalodia yunnanensis sp. nov. are the absence of secondary costae, and spines on its outer surface exhibit a flame-like morphology. Rhopalodia inflata sp. nov. is distinguished from other Rhopalodia species by the pronounced dorsal middle inflation, blunt-pointed spines, and areolae occluded by volae that consist of two or three c-shaped openings. The areolae of R. fuxianensis sp. nov. are covered by raised siliceous petal-like occlusions with one to two siliceous processes. Phylogenetic analysis based on the SSU rDNA and rbcL sequence data places the three new species within a distinct clade, clearly separated from other sequenced Rhopalodia species, including the generitype, R. gibba. In addition, the plastid, mitochondrial, and spheroid body genomes of the three novel species are presented and characterized in this paper.
Nuclear genome assembly and annotation for the phagotrophic green alga Nephroselmis pyriformis.
Charvet S, Kim E
J Phycol · 2025 Dec · PMID 41325128 · Full text
Prasinophytes are a globally distributed, diverse polyphyletic group of photosynthetic green algae, displaying a combination of presumably ancestral traits for the Chloroplastida. The Nephroselmidophyceae is a prasinophy...
Prasinophytes are a globally distributed, diverse polyphyletic group of photosynthetic green algae, displaying a combination of presumably ancestral traits for the Chloroplastida. The Nephroselmidophyceae is a prasinophyte clade comprising small biflagellate algae that includes the marine mixoplankton Nephroselmis pyriformis, which was previously shown to feed on bacteria, particularly under low concentrations of dissolved inorganic nutrients. Given its mixotrophic proclivities and phylogenetic position, N. pyriformis has the potential to provide insights into early green algal evolution and ecophysiology. In this study, we have presented a highly contiguous nuclear genome assembly for N. pyriformis. We acquired both Illumina and PacBio long-read data to assemble a 70.8-Mbp nuclear genome annotated with a total of 19,330 protein-coding genes. The genome is inferred to be haploid based on the base frequency distribution at variable sites, together with prior cell biological information from a related species. When compared with four other green algal genomes, N. pyriformis displayed a relatively large proportion of ortholog genes shared with the Chlorophyta. The nuclear genomic data presented here will be valuable for a range of studies, including green algal phylogenomics, genome evolution, and phago-mixotrophy.
Helicosphaera carteri (Prymnesiophyceae) under high carbon dioxide: An experimental study.
Bianco S, Bordiga M, Langer G … +6 more , Ziveri P, Cerino F, Relitti F, Laudicella VA, Di Giulio A, Lupi C
J Phycol · 2025 Dec · PMID 41283763 · Full text
The coccolithophore Helicosphaera carteri is an understudied, yet ecologically and biogeochemically important, marine calcifier. Hence, its response to ocean acidification has implications for ecosystem function and the...
The coccolithophore Helicosphaera carteri is an understudied, yet ecologically and biogeochemically important, marine calcifier. Hence, its response to ocean acidification has implications for ecosystem function and the marine carbon cycle. Here we employed dilute batch cultures featuring a coupled C-system manipulation (295, 444, and 600 μatm CO) to analyze the response of H. carteri in terms of growth rate and particulate carbon production, two key eco-physiological and biogeochemical parameters. We highlight that both growth rate and organic carbon production are CO limited at 295 µatm but are not proton inhibited at 600 µatm of CO. This finding, combined with the maintenance of a stable inorganic production rate, places H. carteri among the coccolithophores less sensitive to seawater acidification. In addition, we tested a widely applied assumption underpinning the determination of carbon production, namely the constancy of particulate carbon quotas over the course of a dilute batch culture. We determined that the assumption holds true, an important validation of a method used in many publications.
Breeding of triploid Undaria pinnatifida through crossing aposporous gametophytes derived from doubled haploid sporophytes with haploid gametophytes.
Shan T, Li Y
J Phycol · 2025 Dec · PMID 41239847 · Publisher ↗
Undaria pinnatifida is an economically important kelp that is extensively farmed in East Asia. Increasingly severe ocean warming makes it urgent to breed new cultivars that are resistant to higher temperatures. Breeding...
Undaria pinnatifida is an economically important kelp that is extensively farmed in East Asia. Increasingly severe ocean warming makes it urgent to breed new cultivars that are resistant to higher temperatures. Breeding of triploid sporophytes is a potential way to achieve this purpose. Diploid gametophytes were previously produced via apospory from heterozygous sporophytes; however, their sex was not pure, making it difficult to conduct a precise cross. In the present study, we addressed this issue by means of obtaining aposporous diploid gametophytes from doubled haploid sporophytes that were produced by self-fertilization of a monoicous gametophyte. The sex of the aposporous diploid gametophytes was determined to be male. We crossed the male diploid gametophytes with three female haploid gametophyte clonal lines and obtained three hybrid sporophyte lines, which were identified to be triploid using flow cytometry analysis. We cultivated the three triploid lines in the open sea and evaluated their economic traits in April. Their total length and blade length were significantly higher than the control cultivar despite their cultivation period being ~2 months shorter than that of the control. Obvious decay was observed in the control, but not in the triploid sporophytes, suggesting that they sustained growth in higher temperatures. The triploid sporophytes formed sporophylls but were not able to release spores in the reproductive season, and thus, they were determined to be sterile. This study provides a novel and precise means for breeding triploid sporophytes in U. pinnatifida, which is expected to be useful for breeding triploid cultivars superior to the current diploid cultivars.
Effects of temperature, photoperiod, irradiance, and nutrient concentration on Asparagopsis taxiformis (Bonnemaisoniaceae, Rhodophyta) tetrasporophytes.
Jung JW, Park JS, Lee J … +2 more , Yoon HS, Kim JK
J Phycol · 2025 Dec · PMID 41235527 · Publisher ↗
Asparagopsis taxiformis has high potential to mitigate enteric methane emissions from livestock due to its high bromoform content. However, the current supply of gametophytes is limited due to insufficient biomass. Year-...
Asparagopsis taxiformis has high potential to mitigate enteric methane emissions from livestock due to its high bromoform content. However, the current supply of gametophytes is limited due to insufficient biomass. Year-round production of gametophyte can address insufficient biomass through a continuous supply of initial biomass from tetrasporophyte. In this study, we evaluated the effects of temperature (10, 20, and 30°C) and photoperiod (8:16, 12:12, and 16:8 h light:dark cycles), as well as irradiance (10, 20, 40, 80, 160 μmol photons · m · s) and nutrient conditions (high nutrient: 500 μM nitrate and 30 μM phosphate; low nutrient: 50 μM nitrate and 3 μM phosphate) on the growth and reproduction of tetrasporophyte of A. taxiformis. Temperature was a key factor in both growth and reproduction, whereas photoperiod was a key factor in reproduction. Growth of tetrasporophyte was inhibited by 10°C regardless of photoperiod. The development of tetrasporangia was only observed at 20°C with an 8:16 h light:dark cycle. At 20°C with an 8:16 cycle, irradiance affected the development of tetrasporangia at high nutrient concentration. The development of tetrasporangia was observed at 20 and 40 μmol photons · m · s, with the highest growth rate observed at 160 μmol photons · m · s without the development of tetrasporangia. These results suggest that controlling irradiance at 20°C on an 8:16 h light:dark cycle under high nutrient concentration can regulate the growth and reproduction of A. taxiformis tetrasporophyte during cultivation.
A hitchhiker's guide to modern, practical cyanobacterial taxonomy.
Dvořák P, Skoupý S, Stanojković A … +10 more , Johansen JR, Villanueva C, Jung P, Briegel-Williams L, Laughinghouse HD, Lefler FW, Berthold DE, Kaštovský J, Hurley AC, Casamatta DA
J Phycol · 2025 Dec · PMID 41222858 · Full text
There has been an explosion of new Cyanobacterial taxa described within the last two decades. Cyanobacteria exhibit incredible ecological versatility and morphological variability, and thousands of species have already b...
There has been an explosion of new Cyanobacterial taxa described within the last two decades. Cyanobacteria exhibit incredible ecological versatility and morphological variability, and thousands of species have already been described using "traditional" approaches (e.g., morphological features). However, DNA sequencing and other molecular tools have provided extensive evidence that the diversity of cyanobacteria is not necessarily congruent with morphology, as many morphological genera (e.g., Phormidium, Leptolyngbya, and Nostoc) are polyphyletic, and species within the genera are often morphologically indistinguishable, thus cryptic. Further confounding systematic assessments, newly erected taxa are often based on a single strain with one or two 16S rRNA gene sequences, may have incomplete formal descriptions, and lack indication of the employed species concepts. Here we have proposed a set of guidelines for cyanobacterial taxonomists. We have focused on the whole process of erecting new taxa: sampling, sequencing (including genomes), phylogenetic inference, phenotype characterization, species concepts, formal descriptions, and codes of nomenclature. Our hope is that these guidelines will help with the laborious but ever-rewarding task of identifying and describing the taxa within the world of cyanobacteria.
Diversity of Dapis (Microcoleaceae, Cyanobacteria) from coastal marine benthic proliferations in Florida (United States) with the description of three new species.
Berthold DE, Lefler FW, Moretto JAS … +1 more , Laughinghouse HD
J Phycol · 2025 Dec · PMID 41211959 · Publisher ↗
Dapis, along with other benthic cyanobacteria, forms large extensive proliferations (i.e., blooms, mats) that cover sand and seagrass beds across the coasts of Florida, United States. As these benthic cyanobacteria becom...
Dapis, along with other benthic cyanobacteria, forms large extensive proliferations (i.e., blooms, mats) that cover sand and seagrass beds across the coasts of Florida, United States. As these benthic cyanobacteria become more prevalent, especially in areas like the Indian River Lagoon (IRL), Sarasota Bay, Lemon Bay, Tampa Bay, and the Florida Keys, it is necessary to understand their diversity. To explore the diversity and identify the causative species of these nuisance marine benthic mats, growing and rafting mats were sampled. Three cyanobacterial isolates from marine mats across Florida were characterized and revealed to represent three novel species of Dapis, but with differing morphological features than those of previously described species. With the support of 16S rRNA gene sequence phylogeny, morphological evaluations, 16S-23S ITS rRNA region pairwise distances, and phylogenomic analyses, we have presented three novel species of Dapis. We have also provided taxonomically validated sets of Dapis genomes from several species.
Reference genome for the benthic marine diatom Psammoneis japonica: Bacterial associations and repeat-driven genome size evolution in diatoms.
Roberts WR, Parks M, Ashner M … +9 more , Ashworth MP, Denne N, Ruck EC, Spiliotopoulos E, Wang A, Amin SA, Schaack S, Wickett NJ, Alverson AJ
J Phycol · 2025 Dec · PMID 41211940 · Full text
We sequenced the genome, transcriptome, and bacterial metagenome of Psammoneis japonica, a benthic, chain-forming, and araphid marine diatom. This combination of traits fills several gaps in genome sequencing coverage ac...
We sequenced the genome, transcriptome, and bacterial metagenome of Psammoneis japonica, a benthic, chain-forming, and araphid marine diatom. This combination of traits fills several gaps in genome sequencing coverage across diatoms. The nuclear genome (QPGO00000000) is an estimated 91.4 Mb in length, with 11,047 genes that comprise 18% of the total genome. Repetitive elements account for 33% of the genome, and other noncoding sequences comprise the remaining 49% of the genome. A global analysis of diatom genomes showed that repetitive elements are the principal driver of genome size variation in diatoms. Four complete genomes of Planctomycetota, ɑ-proteobacteria, and Bacteroidota were also recovered, and each had only moderate similarity to previously sequenced bacterial genomes. This finding supports the idea that bacterial species richness in the phycosphere is under-described and far exceeds the number of diatom host species, which themselves number in the tens to hundreds of thousands of species.
Occurrence of the calcifying brown alga Newhousia (Dictyotales, Phaeophyceae) in Southeast Asia.
Nguyen LM, Nguyen VX, Kim MS … +1 more , Vieira C
J Phycol · 2025 Dec · PMID 41159447 · Publisher ↗
The calcifying brown algal genus Newhousia (Dictyotales, Phaeophyceae) was previously reported from scattered Pacific localities, including Hawaii and Guam (Northern Hemisphere), French Polynesia, Papua New Guinea, and V...
The calcifying brown algal genus Newhousia (Dictyotales, Phaeophyceae) was previously reported from scattered Pacific localities, including Hawaii and Guam (Northern Hemisphere), French Polynesia, Papua New Guinea, and Vanuatu (Southern Hemisphere). We report here the occurrence of Newhousia from Southeast Asia, based on collections from Nha Trang Bay, Vietnam, representing a record from continental Asia and the westernmost occurrence of the genus. Multigene molecular analyses (psbA, rbcL, cox1, and cox3) identified the Vietnamese specimens as Newhousia imbricata. Morphological observations corroborated its diagnostic vegetative proliferation by eruption of new blade primordia. These findings extend the known distribution of Newhousia to Southeast Asia and highlight the ecological breadth of N. imbricata. They also emphasize the urgent need for expanded surveys across the Indo-Pacific to better resolve the genus's biogeography and diversity, which in turn will provide the foundation for deeper investigations into its dispersal mechanisms, evolutionary history, and reproductive biology.
Magniporophytum gen. nov. and Orientalilithon gen. nov. (Hapalidiales, Corallinophycidae): Two new genera of coralline red algae from the Pacific Ocean, including the description of three new species.
Min-Khant-Kyaw, Kato A, Baba M
J Phycol · 2025 Dec · PMID 41144818 · Full text
We propose, based on a robust set of molecular and morpho-anatomical data of specimens from warm-temperate Japan, two new genera of non-geniculate coralline algae accommodating both attached and rhodolith-forming species...
We propose, based on a robust set of molecular and morpho-anatomical data of specimens from warm-temperate Japan, two new genera of non-geniculate coralline algae accommodating both attached and rhodolith-forming species: Magniporophytum gen. nov. containing M. variabile sp. nov. (the generitype) and M. epizoicum sp. nov. as well as Orientalilithon gen. nov. containing O. confluens sp. nov. (the generitype) and two undescribed Orientalilithon spp. Our multigene phylogenies inferred from psbA, rbcL, and SSU rDNA gene sequences demonstrated the distinct phylogenetic placements of Magniporophytum and Orientalilithon within the Hapalidiales; however, their generic positions have yet to be confirmed. In the psbA gene analyses, an undescribed Hapalidiales sp. 2 from Canada was separately grouped with the congeners of Magniporophytum from Japan, while an undescribed Lithothamnion sp. 5 from Taiwan was conspecific with Orientalilithon sp. 2 from Japan. Morpho-anatomically, the two new genera share some degrees of overlapping characters but can be distinguished by the shape of epithallial cells and the size of tetra/bisporangial pore openings compared to the surrounding rosette cells in surface view. The new genera differ from other phylogenetically related or morpho-anatomically similar genera by a suite of characters regarding epithallial cells, sub-epithallial initials, and tetra/bisporangial conceptacle characters. Within Magniporophytum, M. variabile and M. epizoicum are barely distinguishable, with a single difference in growth form. This study has highlighted a plausible generic character within the Hapalidiales along with the crypticity of coralline algae at both genus and species ranks and the extended distributions of Magniporophytum and Orientalilithon in the North Pacific Ocean.
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