Genome size is a fundamental characteristic of the cell and is associated with a number of key features of the organism, such as cell size, division rate or metabolic rate. Knowledge of the genome size is also a prerequisite for many areas of research (e.g. selection of suitable organisms for whole genome sequencing or cell cycle analysis). However, genome size analysis in microalgae is often difficult and involves many methodological challenges. As a result, genome size data for microalgae are largely lacking. In this study, we focused on fragile, poorly growing colonial chrysophytes. We analysed their genome size using flow cytometry and tested the difference between colonial and solitary living chrysophytes on all published genome size data using analysis of variance. We successfully established nine cultures that were further determined to belong to six species of colonial chrysophytes. We estimated their genome size to be on average 0.24 pg & centerdot;cell-1 for Chrysosphaerella longispina Lauterborn, 1.70 pg & centerdot;cell-1 for Neotessella lapponica (Skuja) B.Y.Jo, J.I.Kim, W.Shin, P.& Scaron;kaloud & P.A.Siver, 0.25 pg & centerdot;cell-1 for Uroglenopsis turfosa (Skuja) R.H.Thompson & D.E.Wujek, 0.31 pg & centerdot;cell-1 for Urostipulosphaera articulata (Korshikov) Pusztai & & Scaron;kaloud, 0.22 pg & centerdot;cell-1 for U. granulata Pusztai & & Scaron;kaloud and 0.19 pg & centerdot;cell-1 for U. lindiae (Bourrelly) Pusztai & & Scaron;kaloud. It was also shown that colonial chrysophytes have larger genomes compared to solitary living species. This study further revealed the smallest genome among colonial chrysophytes, belonging to Urostipulosphaera lindiae. Nevertheless, colonial chrysophytes have lower variance in genome size, possibly due to evolutionary constraints on cell size (and genome size) variation to maintain the functionality of the whole colony movement.
Chara braunii C.C.Gmelin, C. pseudohydropithys Imahori, and Nitella laotica R.E.Romanov, V.Yu Nikulin, K.-G.Bernhardt & A.A.Gontcharov, sp. nov. are reported for Laos. These records seem to be the first species records of charophytes for the country. Chara pseudohydropithys is lectotypified here and described in detail. It is the first record for Southeast Asia, extending its distribution range from mainland China, Taiwan, India, and Brazil. We mention this first record of C. braunii which is a frequently reported species in well-studied regions of Southeast and East Asia, because of the complete absence of records of charophytes from Laos. Nitella laotica sp. nov. is described as a new species using integrative taxonomy. The plants of N. laotica sp. nov. are macrodactylous, homoclemous, with mostly two-furcated branchlets, some branchlets one-two-or two-three-furcated, with or without central secondary ray within the same thallus and the same whorl, without accessory branchlets originating from central secondary rays or any furcation of branchlets, with bicellular dactyls and conical and mucronate end cells, solitary conjoined gametangia at first and more frequently at second furcation of branchlets, with reticulate ornamentation on both oospore surface and low spiral striae. The formation of ripe oospore surface is tentatively outlined for N. laotica sp. nov. This species is similar to N. oligospira A.Braun, a species distinctly different in morphology, in rbcL and ITS rDNA data. Further studies of charophytes are essential for Laos because the three species found there do not correspond to the species richness that can be expected for charophytes in a tropical country with a humid climate.
The systematic status of the newly proposed genus Stirkia Barros-Barreto & Maggs and its relationship to the currently accepted name Ceramothamnion H.Richards remain uncertain because no authentic specimens of the generitype C. codii H.Richards from the type locality in Bermuda have been sequenced. To clarify the taxonomy of C. codii, we performed high-throughput sequencing on a topotype, a 1912 Phycotheca Boreali-Americana (P.B.-A.) specimen collected by F.S. Collins. The rbcL, COI-5P and LSU genetic markers from the P.B.-A. specimen were assembled and used to infer gene and multi-gene phylogenies to determine its phylogenetic history. In all analyses, the topotype of C. codii was closely allied with C. fujianum Barros-Barreto & Maggs, the generitype of Stirkia, as well as with other species of Ceramothamnion from the southwestern Atlantic and Pacific Oceans. These data support the relegation of the genus Stirkia to Ceramothamnion and indicate that the only previously published DNA sequences of C. codii, from Hawai'i, represent a different, presumably undescribed species of Ceramothamnion. They also highlight the power of whole genome sequencing and the need to analyse type, topotype, or historically authentic herbarium specimens to ensure the accurate application of algal binomials.
We report on a new record of Sargassum hornschuchii C.Agardh in the Spanish Mediterranean after having no reports for more than a century. Sargassum hornschuchii was found in a deep-water rocky bottom offshore Menorca together with the kelp Laminaria rodriguezii Bornet and the rockweed Ericaria zosteroides (C.Agardh) Molinari & Guiry. We make an accurate morphological description and provide pictures of the specimens collected. This new record puts into question the assignment of the IUCN "extinct" category for deep-water rare macroalgae as they can go unnoticed for a long time. This also highlights the need to protect remote deep-water spots where biodiversity can still be flourishing.
Crypsis-high morphological similarities of adult thalli of distinct species of algae-is a common challenge in algal taxonomy, where multiple taxa are characterized as the same species due to identical morphologies. Algal genera with cryptic species and similar morphologies may contain underestimates of both diversity and endemism. Extensive studies of Mesophotic Coral Ecosystems (MCEs; from c. 30 to >150 m depths) have revealed high levels of endemism in the Hawaiian Archipelago using DNA sequence-based analyses augmented by morphological analyses. Here, we characterize specimens collected from both the Papah & amacr;naumoku & amacr;kea Marine National Monument and the Main Hawaiian Islands corresponding to the genus Gloiocladia J.Agardh; previous reports from Hawai'i included only a single subtidal species (G. iyoensis (Okamura) R.E.Norris). Phylogenetic analyses using both plastidial (ribulose-1.5-biphosphate carboxylase/oxygenase) and mitochondrial (cytochrome oxidase subunit 1) markers revealed three clades of Hawaiian specimens with strong sequence divergence. However, the gross morphology of these specimens was nearly identical, except for small differences in the number of layers and sizes of cortical and medullary cells, which can easily be overlooked. This study extended the depth record of G. iyoensis to 63 m (aside from a previous report of a dredge sample from 66 m) and revealed one new species exclusive to MCEs (described here as G. laukuamoo K.R.Allsopp, F.P.Cabrera & A.R.Sherwood, sp. nov.), as well as one new intertidal species (formal description awaiting analysis of further collections) present in the Hawaiian Archipelago, including the Papah & amacr;naumoku & amacr;kea Marine National Monument (PMNM) and the Main Hawaiian Islands.
We present the results of a taxonomic survey of desmidiales (Desmidiaceae Ralfs, Zygnematophyceae Round ex Guiry) in floodplain lakes and tributaries of the Napo-Aguarico River in the Ecuadorian Amazon. Surface water samples were collected for taxonomic analysis at each site during two different hydrological periods in 2021 and 2022. Our sites share a typical blackwater typology, with high water transparency, low conductivity, acidic, and soft waters. In this study we documented 42 specific or infraspecific taxa in 10 genera within the Desmidiaceae family: Bambusina K & uuml;tzing ex K & uuml;tzing (1), Cosmarium Corda ex Ralfs (9), Desmidium C.Agardh ex Ralfs (3), Euastrum Ehrenberg ex Ralfs (3), Hyalotheca Ehrenberg ex Ralfs (2), Micrasterias C.Agardh ex Ralfs (12), Pleurotaenium N & auml;geli (2), Staurastrum Meyen ex Ralfs (6), Staurodesmus Teiling (2), and Xanthidium Ehrenberg ex Ralfs (2). From those taxa, 15 are new records to the lowlands of western Amazonia, and three of them (Cosmarium quadriverrucosum var. supraornatum Skuja, Micrasterias fimbriata var. spinosa Bisset, and Micrasterias furcata var. dichotoma (Wolle) R & uring;& zcaron;i & ccaron;ka) to the Amazon Basin. The number of species recorded at various sites differed greatly. We found 28 taxa for the Lagartococha River and 27 for Delfincocha Lake. For the remaining sites, we observed only two to nine species, which may be related to the presence or absence of aquatic macrophytes. All taxa were recorded during 2022, but only 20 out of 42 were observed in 2021. This variation is likely due to the hydrological regime, as it occurs in other Neotropical floodplains. Our findings underscore the importance of conducting additional phycological studies in these largely unexplored ecosystems, which are in peril owing to oil extraction activities in the western region of the Amazon Basin.
Disjunct distributions provide an intriguing issue for our understanding of the biogeography of marine algae because of their lack of the active dispersal potential. The present morphological and molecular study reports the unexpected occurrence of a grateloupiacean red alga Yonagunia taiwaniborealis S.-M.Lin, Y.-C.Chuang & De Clerck from Lembongan Island, Southern Indonesia, a species which was considered endemic to northern Taiwan. Indonesian specimens were examined and are in good morpho-anatomical agreement with the Taiwanese type material. Plastid rbcL sequence divergence of both Indonesian and Taiwanese specimens was 0.08%. The disjunct distribution of Y. taiwani-borealis across the Equator likely represents a refugia population in an upwelling area that was isolated from formerly widespread populations. Yonagunia taiwani-borealis was large in height and abundant, likely functioning as foundation species of rocky shore community. This is the first record of Y. taiwani-borealis outside of northern Taiwan. This result raises the likelihood of other disjunct distributions of red algae between these two opposite areas of coastal upwelling in Southeast Asia.
The order Halymeniales represents a significant number of species in the mesophotic red algal flora of Hawai'i, with numerous undescribed taxa. The cultivation and restoration of species in the Halymeniales in Hawai'i, particularly members of Grateloupia C.Agardh and Halymenia C.Agardh, have focused substantial attention on these taxa, highlighting uncertainty in the genetic diversity within this group. In this study, we adopt a taxogenomic approach integrating taxonomic, phylogenetic and phylogenomic analyses. We present the first report of the genus Amalthea D'Archino & W.A.Nelson in Hawai'i, focusing on the species description of Amalthea mahilanii F.P.Cabrera & A.R.Sherwood, sp. nov. Our initial rbcL analysis suggested the presence of two lineages within Hawaiian Amalthea, but robust support from plastome-wide phylogenies contradicted that analysis, emphasizing the value of taxogenomics in clarifying cryptic diversity. Morphologically distinct from congeners Amalthea freemaniae D'Archino & W.A.Nelson and A. rubida H.W.Lee & M.S.Kim, A. mahilanii F.P. Cabrera & A.R.Sherwood, sp. nov. features rough, leathery blades with a unique cortical and medullary cell arrangement, including 9-10 layers of ovoid cortical cells and a dense arrangement of medullary filaments. Its blades maintain uniform thickness. The presence of larger ostiolate cystocarps (300-500 mu m diameter) further distinguishes A. mahilanii F.P.Cabrera & A.R.Sherwood, sp. nov. from its Pacific conspecifics. Syntenic comparisons of published plastomes within the Halymeniales revealed remarkable similarities in gene content, with no detected rearrangements, indicating conserved plastidial evolution within the order. Overall, this study significantly advances our understanding of Halymeniales diversity in mesophotic ecosystems, shedding light on the remarkable biodiversity of macroalgae in Hawaiian mesophotic reefs. We emphasize the need for further study of Halymeniales and propose ongoing efforts in taxogenomics to enhance taxonomic resolution, particularly in mesophotic habitats.
With 35 currently recognised species, Prasiola Meneghini, 1838 is the largest genus of the family Prasiolaceae (Prasiolales, Trebouxiophyceae). However, recent molecular phylogenetic studies have shown that the genus as currently conceived is polyphyletic, due to a separate genus, Prasiococcus Vischer, clearly being nested between the Prasiola clades. Since the clade containing the type species Prasiola crispa (Lightfoot) K & uuml;tzing has priority, we propose three new taxonomic realignments, based on DNA sequence comparisons, for two clades containing four and two species of Prasiola, respectively, and for another single species. The genus Mariprasiola Heesch, Guiry & Rindi, gen. nov., comprising the four species M. stipitata (Suhr ex Jessen) Heesch, Guiry & Rindi, comb. nov., the type, M. delicata (Setchell & N.L.Gardner) Heesch, Guiry & Rindi, comb. nov., M. linearis (C.-C.Jao) Heesch, Guiry & Rindi, comb. nov. and M. meridionalis (Setchell & N.L.Gardner) Heesch, Guiry & Rindi, comb. nov., distributed in marine habitats. Two species of Vittaprasiola Heesch, Guiry & Rindi, gen. nov., the strictly terrestrial species V. calophylla (Carmichael ex Greville) Heesch, Guiry & Rindi, comb. nov., the type, and the freshwater species V.fluviatilis (Sommerfelt) Heesch, Guiry & Rindi, comb. nov., share a belt-like appearance. Eaprasiola Heesch, Guiry & Rindi, gen. nov. is currently monospecific, with E. japonica (R.Yatabe) Heesch, Guiry & Rindi, comb. nov., found in freshwater habitats in East Asia and with thalli reaching up to 20 cm in length, the largest known representative of the family. Since the remaining 21 species of Prasiola lack genetic data, they cannot at present be assigned to any genus and remain in the genus Prasiola sensu lato.
The Mediterranean Sea is worldwide the area most affected by introduced species. The Suez Canal (Lessepsian species) and shellfish aquaculture are the main routes for introduction, in addition to shipping (fouling, clinging and ballast waters). Two non-indigenous Lophocladia (Montagne) F.Schmitz species have been recorded from the Mediterranean Sea: the Red Sea and Indian Ocean L. lallemandii (Montagne) F.Schmitz and the western tropical Atlantic Ocean L. trichoclados (C.Agardh) F.Schmitz. On the basis of molecular data, Golo et al. (2023, 2024) concluded that the species which invaded the Mediterranean only belongs to the western Atlantic L. trichoclados. Until the mid-2010s, the north of the western basin was the only Mediterranean area not invaded by this species. In the present paper, we report for the first time the presence of L. trichoclados from this region in Provence and Corsica. Interestingly, L. trichoclados does not occur and bear reproductive organs in spring but in autumn and winter, although it is a species of tropical affinity.
This study introduced a new species of freshwater red alga discovered in Taiwan, Virescentia asiaticasp. nov. Using genetic and morphological analyses, we determined its taxonomic status and phyloge-netic relationship among other species of Virescentia(Sirodot) Necchi, D.C.Agostinho & M.L.Vis. While Virescentia taxonomy and species diversity have been extensively explored in Europe and the Americas, Asia remained less studied, with only one new species described in China. This study was the first record of Virescentia in Taiwan and confirmed it as a new species, Virescentia asiaticasp. nov.The investigation was based on comparing morphological characteristics and genetic markers rbcL and COI-5P in collections from around the world. Molecular evidence showed what we describe as V. asiaticasp. nov. forming a well-supported clade with four previously unidentified Virescentia se-quences from Japan, and conspecific with at least three of these. We considered it likely that V. asiaticasp. nov. inhabited a wider geographic range in East Asia, including other regions besides Taiwan and Japan. Morphologically, Virescentia asiaticasp. nov. was distinct only in habit, differing from other Virescentia species in having an apparently diminutive thallus and curved branching. This study enhanced our understanding of the classification and phylogenetic relationships within Virescentia, contributing to the knowledge of freshwater red algae biodiversity in East Asia.
Haploid-diploid life cycles impose unique eco-evolutionary consequences, rendering commonly used proxies difficult to use (e.g. separate sexes prevent selfing). Population genetic analyses are therefore required to explore patterns of reproductive system variation. However, there are still few haploid-diploid species for which polymorphic, nuclear loci exist. This problem is particularly acute for algae. Here, we describe the development of the first microsatellite loci in a freshwater red alga. We tested 73 candidate loci against a panel of Batrachospermum gelatinosum (L.) De Candolle gametophytes that encompass much of its North American range. Ten loci consistently amplified and were characterized by clean peak architectures on a capillary sequencer with one allele per locus, as expected in a haploid gametophyte. We then explored some basic population genetic indices in gametophytes collected from one site and obtained good resolution based on the probability of identity (pid). Yet, we observed a pattern of clumped repeated genotypes throughout the stream reach sampled. The pattern of moderate genotypic richness could be due to intragametophytic selfing resulting in the complete loss of genetic diversity from a single gamete union. Future studies will need to sample more populations to determine if intragametophytic selfing is the dominant reproductive mode in this monoicous taxon. The loci developed here represent an important tool for studying freshwater red algal populations in specific as well as enhancing our understanding of reproductive system variation and the haploid-diploid life cycle of algae in general.
To increase the knowledge on diversity of freshwater cyanobacteria, we have characterized a novel filamentous, benthic cyanobacterium isolated from a pond in Golestan province, Iran. The isolate was studied using a polyphasic approach based on morphological and molecular characteristics, including phylogenetic and structural analysis of the 16S rRNA gene sequence and 16S to 23S internal transcribed spacer (ITS), respectively. The overall morphology of the isolate was similar to Nostocalean member's strains with non-tapering filaments and distributed heterocytes. However, the molecular analyses suggested that it was more closely related to the lithobiont and rock-dwelling Goleter apudmare Miscoe & J.R.Johansen, which has tapered filaments and basal heterocytes. The 16S rRNA gene phylogenetic analysis, based on bayesian inference and maximum likelihood methods, placed the isolate close to G. apudmare. The D1-D1', Box-B and V3 helixes of the isolate's ITS sequence were different when compared to other Goleter ITS sequences. Similar to G. apudmare HA4356-MV2 (JN385288.1) and Goleter sp. CHAB TP201702 (MT488126.1), tRNA genes were absent from the amplified ITS sequence in the studied isolate. These morphological and molecular characteristics differentiate this isolate from all other Goleter taxa described so far, which contributes to extend the knowledge on cyanobacterial diversity and occurrence of benthic cyanobacteria in Iranian freshwaters.
The findings of this study expanded the geographic distribution of the genus Corynecladia J.Agardh, thought to be endemic to Australia. It is recorded for the first time as present in Europe, with two newly proposed species: C. millarii sp. nov. and C. mediterranea sp. nov. New collections belonging to the Laurencia complex were sampled from the Sicilian coasts of Italy. Examination of this material was carried out using both morphological comparisons and phylogenetic analyses of chloroplast (rbcL) and mitochondrial (COI-5P) nucleotide sequences. The resulting phylogenetic trees divided the Mediterranean specimens into two supported, separate branches, within the genus Corynecladia. Morphological analysis supported placement of these species within Corynecladia and as distinct from other congeners. Specifically, the two new species were conspicuous in the absence of a secondary cortex which is typical of other Corynecladia taxa. Included in this study is a detailed dichotomous key to the Laurencia complex taxa of the Mediterranean.
The marine microfilamentous green algal genus Okellya Leliaert & Rueness forms a distinct lineage of Cladophorales Haeckel, and currently contains only a single species, Okellya curvata (Printz) Leliaert & Rueness, originally described as Uronema curvatum Printz from Norway. Based on phylogenetic analyses of SSU and LSU rDNA sequences, we show that the Australian Uronema marinum Womersley also belongs to Okellya, and the species is transferred there as O. marina (Womersley) Wetherbee, comb. nov. We provide detailed observations of cultured material and show that O. marina (Womersley) Wetherbee, comb. nov. differs from O. curvata in the presence of pyrenoids, necessitating a revised circumscription of the genus Okellya and family Okellyaceae Leliaert & Rueness.
During a genetic analysis of western Atlantic Wrangeliaceae J.Agardh, specimens closely related to the generitype of Lophothamnion J.Agardh fell into a clade including the generitype of the earlier described Pleonosporium Nageli, causing us to subsume the former genus. Two new species are described, P. novae-angliae G.W.Saunders & C.W.Schneider, sp. nov. for specimens from southern New England and New York, United States, formerly identified there as P. borreri (Smith) Nageli, and P. ricksearlesii C.W.Schneider & G.W.Saunders, sp. nov. from Bermuda. The relationship of Pleonosporium with its sister genus Spongoclonium Sonder is discussed with the transfer of Spongoclonium australicum Womersley to Pleonosporium.
Species of the marine benthic dinoflagellate genus Gambierdiscus Adachi & Fukuyo are morphologically similar, and DNA based sequence analyses are necessary to complement morphological species determination. Gambierdiscus species may produce ciguatoxins, the causative agents of human illness ciguatera poisoning (CP). In this study, morphological descriptions, based on laboratory cultures, using light and scanning electron microscopy and DNA based characterisation of one strain (ISOG4) isolated from Petite Riviere Noire, Mauritius are provided. Our morphological observations coupled with DNA based sequence analyses indicate that the Mauritian strain is Gambierdiscus caribaeus Vandersea, Litaker, M.A.Faust, Kibler, W.C.Holland & P.A.Tester. Our strain bears close similarity (LSU 99% identity) to Gambierdiscus caribaeus (GenBank[KY448444]) isolated from Canary Islands, Spain, and phylogenetic results depict it as sister to G. jejuensis S.H.Jang & H.J.Jeong. Gambierdiscus caribaeus (ISOG4) is herein a first report from Mauritius Island and the Mascarene region.
Cyanobacteria are a lineage of Eubacteria that have long captured the attention of scientists. Approximately 5310 species of cyanobacteria have been hitherto described and new species are continually being found, named and described according to established rules. The correct determination of cyanobacteria strains concerns new biotechnological applications as well as ecological studies. There are many situations where it is crucial to recognise distinct algae species, however methods for doing so vary greatly. The aim of this review is to summarize the state of the art of the main and most recent molecular studies focusing on the phylum Cyanobacteria, with particular attention to the most frequently used gene markers. For a long time, the classification method used for cyanobacteria as well as traditionally described species was mainly based on morphology. Over time, integrative taxonomy, which involves the inclusion of many characters and comprehensive taxa sampling, has become the rule as it provides a better resolution of species relationships. For a better resolution of the phylogenies of the phylum Cyanobacteria, it is usually necessary to focus on different genetic markers: from the most common, like the 16S and 23S rRNA, ITS, rbcLXS and rpoC genes, to genes not so widely used, such as hetR, psbA, tufA, gyp and cpcBA. Also, the highly repetitive sequences often used for the symbiotic cyanobacteria represent an important factor in the inference of the phylogenetic relationships.
Seven species from the genera Kobayasiella (K. madumensis Jorgensen, K. micropunctata Germain, K. parasubtilissima Kobayasi & Nagumo, K. pseudostauron Lange-Bertalot, K. subtilissima P.T.Cleve), Adlafia (A. bryophila Petersen) and Nupela (N. tenuicephala Hustedt) from oligotrophic lakes of the subarctic boreal zone in Tursujuq National Park in Nunavik (northern Quebec, Canada), were studied by light and scanning electron microscopy and linked with environmental conditions. In addition, four new species, Kobayasiella tursujuqensis sp. nov., Adlafia umiujaqensis sp. nov., Adlafia ossiformis sp. nov., and Sellaphora vincentiana sp. nov., were observed and described. The new species are similar in light microscope observations to other species in their associated genera, but can be identified based on independent character traits under a combined LM and SEM analysis. Morphological structures of particular interest include valve outline, position of the central and terminal raphe fissures, orientation of the striae, and the structural formation of the areolae within the striae. Due to low taxon abundances, distribution patterns of these species in the park were difficult to identify. Kobayasiella parasubtilissima, K. subtilissima, K. tursujuqensis sp. nov. and N. tenuicephala were associated with acidic conditions while K. pseudostauron, A. bryophila and S. vincentiana sp. nov. were found in circumneutral waters. A better knowledge of small naviculoid species is necessary to document the circumpolar biogeography and ecology of diatoms for a better understanding of the dynamic of those organisms in changing environmental conditions within the context of rapid climate change in northern regions.
