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The genus Coelastrum Nägeli (Sphaeropleales; Scenedesmaceae) is a diverse genus of green algae with potential biotechnical applications. A sound understanding of its phylogeny will be a useful tool for predicting the distribution of traits that may enhance its utility, and may lead to a better understanding of its evolution and ecology. Here we present the plastome of Coelastrum microporum. Our exemplar was isolated from Gull Lake, Michigan and the complete plastome as assembled was 169,961 bp in length. The plastome contained 104 genes of which 68 were protein-coding genes (CDSs), 27 tRNA genes and three rRNA genes. The GC content of the plastome was 31.2%. The maximum likelihood phylogeny suggested that C. microporum was the sister group to a clade of single exemplars of three other genera in the Scenedesmaceae (Tetradesmus, Pectinodesmus and Coelastrella).

The genus Coelastrum Nägeli (Sphaeropleales; Scenedesmaceae) is a diverse genus of green algae with potential biotechnical applications. A sound understanding of its phylogeny will be a useful tool for predicting the distribution of traits that may enhance its utility, and may lead to a better understanding of its evolution and ecology. Here we present the plastome of Coelastrum microporum. Our exemplar was isolated from Gull Lake, Michigan and the complete plastome as assembled was 169,961 bp in length. The plastome contained 104 genes of which 68 were protein-coding genes (CDSs), 27 tRNA genes and three rRNA genes. The GC content of the plastome was 31.2%. The maximum likelihood phylogeny suggested that C. microporum was the sister group to a clade of single exemplars of three other genera in the Scenedesmaceae (Tetradesmus, Pectinodesmus and Coelastrella). [ABSTRACT FROM AUTHOR]

We sampled the first mitogenomes from a novel lineage of the Chlorophyceae that is sister to Sphaeropleales. Although the Jenufa perforata (27,180 bp) and Jenufa minuta (41,488 bp) mitogenomes differ markedly in size, gene order and intron content, their repertoires of conserved genes are essentially identical. Their rRNA genes display the same fragmentation patterns as their counterparts in Sphaeropleales. Their tRNA gene complements include two ancestral genes shared with Oedogoniales and Chaetophorales (Chlorophyceae) as well as a derived gene for a tRNA species decoding UGA as tryptophan. This noncanonical genetic code differs from those previously reported for Sphaeropleales.

We describe the plastome of Jenufa minuta, a unicellular green alga whose precise relationship with the Sphaeropleales (Chlorophyceae) remains uncertain. This 206,680-bp genome contains 100 conserved genes, 11 of which exhibit 16 group I and seven group II introns. We discovered a trans-spliced group II intron in the rpl32 gene of J. minuta and its orthologs in all Sphaeropleales and several Chlamydomonadales; this is the first time this intron is documented. As in the mitochondria of J. minuta, the UGA codon is decoded as tryptophan. To our knowledge, this is the second report of a variant genetic code in plastids.

Sixteen monoclonal strains classified into six morphotypes typical of, or close to, intraspecific taxa of Pseudopediastum boryanum, including P. alternans (ALT), P. boryanum var. boryanum (BOR), P. boryanum var. cornutum (COR), P. boryanum var. forcipatum (FOR), P. boryanum var. longicorne (LON), and P. boryanum var. perforatum (PER), were simultaneously subjected to phylogenetic (26S rDNA and rbcL cpDNA) and morphometric analyses. Marginal cell shape, coenobium and cell size, and granule density on the cell surface were analyzed statistically. The shapes of some morphotypes (BOR, COR, FOR, and PER) were also compared to the shapes of corresponding type illustrations. Pseudopediastrum boryanum var. boryanum, without any reliable morphological and phylogenetic data, appeared to be a questionable taxon that needs a neotype. The variety longicorne proved to be a complex taxon that should be split after morphometric data of more strains and of the corresponding lectotype are included in the statistical analysis. A new species, Pseudopediastrum oblongum, was described, and four varieties were elevated to the species level, which resulted in establishing new combinations, P. cornutum, P. forcipatum, P. perforatum, and P. subgranulatum. Reference sequences for the new species and combinations were obtained. The paleoecological value of P. boryanum sensu lato appeared to be limited by the relatively low percentage of marginal cells typical of particular varieties and a high risk of their misidentification in the light microscope. The shape of marginal cells seemed to be the best diagnostic feature. Granule density could be helpful to discriminate between certain taxa. [ABSTRACT FROM AUTHOR]

Mitochondria of diverse eukaryotes have evolved various departures from the standard genetic code, but the breadth of possible modifications and their phylogenetic distribution are known only incompletely. Furthermore, it is possible that some codon reassignments in previously sequenced mitogenomes have been missed, resulting in inaccurate protein sequences in databases. Here we show, considering the distribution of codons at conserved amino acid positions in mitogenome-encoded proteins, that mitochondria of the green algal order Sphaeropleales exhibit a diversity of codon reassignments, including previously missed ones and some that are unprecedented in any translation system examined so far, necessitating redefinition of existing translation tables and creating at least seven new ones. We resolve a previous controversy concerning the meaning the UAG codon in Hydrodictyaceae, which beyond any doubt encodes alanine. We further demonstrate that AGG, sometimes together with AGA, encodes alanine instead of arginine in diverse sphaeroplealeans. Further newly detected changes include Arg-to-Met reassignment of the AGG codon and Arg-to-Leu reassignment of the CGG codon in particular species. Analysis of tRNAs specified by sphaeroplealean mitogenomes provides direct support for and molecular underpinning of the proposed reassignments. Furthermore, we point to unique mutations in the mitochondrial release factor mtRF1a that correlate with changes in the use of termination codons in Sphaeropleales, including the two independent stop-to-sense UAG reassignments, the reintroduction of UGA in some Scenedesmaceae, and the sense-to-stop reassignment of UCA widespread in the group. Codon disappearance seems to be the main drive of the dynamic evolution of the mitochondrial genetic code in Sphaeropleales. [ABSTRACT FROM AUTHOR]

SUMMARY: The present results are the effect of bioprospecting of an appropriate medium, which could optimize the quality and quantity of the microalga Pseudopiediastrum boryanum var. longicorne Reinsch biomass cultured in a laboratory photobioreactor for biosorption purposes. Four liquid media commonly used for cultivation of green algae of the genus Pediastrum were compared, including Knop's, Waris‐H, Chu's and L‐S2T2 media, which differed with respect to the composition and concentration of nutrients. A number of the parameters characterizing biomass growth, namely dry weight, optical density, chlorophyll a concentration, as well as morphological parameters characterizing the condition of the alga and its surface area indicating the potential sorption capacity (population structure, cell number, coenobium size and marginal cell size), showed a significant impact of culture medium on the growth of the microalga. The most productive culture was found in the L‐S2T2 medium containing organic substances in the form of peat and soil extracts, which could be crucial for biomass production and the area of potential sorption capacity. [ABSTRACT FROM AUTHOR]

Genetic code deviations involving stop codons have been previously reported in mitochondrial genomes of several green plants (Viridiplantae), most notably chlorophyte algae (Chlorophyta). However, as changes in codon recognition from one amino acid to another are more difficult to infer, such changes might have gone unnoticed in particular lineages with high evolutionary rates that are otherwise prone to codon reassignments. To gain further insight into the evolution of the mitochondrial genetic code in green plants, we have conducted an in-depth study across mtDNAs from 51 green plants (32 chlorophytes and 19 streptophytes). Besides confirming known stop-to-sense reassignments, our study documents the first cases of sense-to-sense codon reassignments in Chlorophyta mtDNAs. In several Sphaeropleales, we report the decoding of AGG codons (normally arginine) as alanine, by tRNA(CCU) of various origins that carry the recognition signature for alanine tRNA synthetase. In Chromochloris, we identify tRNA variants decoding AGG as methionine and the synonymous codon CGG as leucine. Finally, we find strong evidence supporting the decoding of AUA codons (normally isoleucine) as methionine in Pycnococcus. Our results rely on a recently developed conceptual framework (CoreTracker) that predicts codon reassignments based on the disparity between DNA sequence (codons) and the derived protein sequence. These predictions are then validated by an evaluation of tRNA phylogeny, to identify the evolution of new tRNAs via gene duplication and loss, and structural modifications that lead to the assignment of new tRNA identities and a change in the genetic code. [ABSTRACT FROM AUTHOR]

Many species belonging to the coccoid green algae genus Coelastrella are considered potential candidates for the large-scale production of natural pigments and biofuels. However, little is known about the structural, functional and molecular aspects of the chloroplast genomes (cpDNAs) of this genus. In the present study, the complete sequence of the cpDNA of strain FACHB-2138, which was further identified as Coelastrella saipanensis Hanagata based on morphological and molecular analyses, was elucidated. The 196 140 bp cpDNA sequence that was assembled as a circular map was found to possess the typical quadripartite structure. The two identical copies of 11 897 bp inverted repeat (IR) sequences were separated from one another by single copy regions. The large single copy region (LSC) was 104 949 bp, whereas the small single copy region (SSC) was 67 397 bp. The cpDNA encoded a total of 96 unique genes, which included 67 protein-coding genes, three rRNA genes and 26 tRNA genes. A total of 19 group I introns were annotated in this genome. Comparative analyses with three species from the family Scenedesmaceae showed C. saipanensis had a slightly expanded genome, higher GC content and less skewed distribution of its genes between the two DNA strands than that of the other three species. The cpDNA data deduced from the present study helps to expand our present understanding of plant systematics and phylogenetic reconstruction, and identify the possible biotechnological applications of the species belonging to the studied taxa. [ABSTRACT FROM AUTHOR]

We describe the plastome of Jenufa minuta, a unicellular green alga whose precise relationship with the Sphaeropleales (Chlorophyceae) remains uncertain. This 206,680-bp genome contains 100 conserved genes, 11 of which exhibit 16 group I and seven group II introns. We discovered a trans-spliced group II intron in the rpl32 gene of J. minuta and its orthologs in all Sphaeropleales and several Chlamydomonadales; this is the first time this intron is documented. As in the mitochondria of J. minuta, the UGA codon is decoded as tryptophan. To our knowledge, this is the second report of a variant genetic code in plastids. [ABSTRACT FROM AUTHOR]

We sampled the first mitogenomes from a novel lineage of the Chlorophyceae that is sister to Sphaeropleales. Although the Jenufa perforata (27,180 bp) and Jenufa minuta (41,488 bp) mitogenomes differ markedly in size, gene order and intron content, their repertoires of conserved genes are essentially identical. Their rRNA genes display the same fragmentation patterns as their counterparts in Sphaeropleales. Their tRNA gene complements include two ancestral genes shared with Oedogoniales and Chaetophorales (Chlorophyceae) as well as a derived gene for a tRNA species decoding UGA as tryptophan. This noncanonical genetic code differs from those previously reported for Sphaeropleales. [ABSTRACT FROM AUTHOR]

In this study, the chloroplast genome of Hariotina reticulata was fully sequenced and compared to other Sphaeropleales chloroplast genomes. It is 210,757 bp larger than most Sphaeropleales cpDNAs. It presents a traditional chloroplast structure, and contains 103 genes, including 68 protein-coding genes, six rRNA genes and 29 tRNA genes. The coding region constitutes of 43% of the whole cpDNA. Eighteen introns are found in 11 genes and six introns are unique for Hariotina. 11 open reading frames are identified among these introns. The synteny between Hariotina and Acutodesmus cpDNAs is in general identical, while within Sphaeropleales order, high variability in cpDNA architecture is indicated by general high DCJ distances. Ankyra judayi exhibits the greatest dissimilarity in gene synteny to the others and share some unique gene clusters with Treubaria triappendiculata. The phylogenomic analyses show that A. judayi is clustered with Treubariaceae species and sister to Chlorophyceae incertae sedis and other Sphaeropleales species. The monophyly of Sphaeropleales is rejected. [ABSTRACT FROM AUTHOR]

Premise of the Study: Phylogenomic analyses across the green algae are resolving relationships at the class, order, and family levels and highlighting dynamic patterns of evolution in organellar genomes. Here we present a within‐family phylogenomic study to resolve genera and species relationships in the family Hydrodictyaceae (Chlorophyceae), for which poor resolution in previous phylogenetic studies, along with divergent morphological traits, have precluded taxonomic revisions. Methods: Complete plastome sequences and mitochondrial protein‐coding gene sequences were acquired from representatives of the Hydrodictyaceae using next‐generation sequencing methods. Plastomes were characterized, and gene order and content were compared with plastomes spanning the Sphaeropleales. Single‐gene and concatenated‐gene phylogenetic analyses of plastid and mitochondrial genes were performed. Key Results: The Hydrodictyaceae contain the largest sphaeroplealean plastomes thus far fully sequenced. Conservation of plastome gene order within Hydrodictyaceae is striking compared with more dynamic patterns revealed across Sphaeropleales. Phylogenetic analyses resolve Hydrodictyon sister to a monophyletic Pediastrum, though the morphologically distinct P. angulosum and P. duplex continue to be polyphyletic. Analyses of plastid data supported the neochloridacean genus Chlorotetraëdron as sister to Hydrodictyaceae, while conflicting signal was found in the mitochondrial data. Conclusions: A phylogenomic approach resolved within‐family relationships not obtainable with previous phylogenetic analyses. Denser taxon sampling across Sphaeropleales is necessary to capture patterns in plastome evolution, and further taxa and studies are needed to fully resolve the sister lineage to Hydrodictyaceae and polyphyly of Pediastrum angulosum and P. duplex. [ABSTRACT FROM AUTHOR]

The genus Coelastrum Nägeli (Sphaeropleales; Scenedesmaceae) is a diverse genus of green algae with potential biotechnical applications. A sound understanding of its phylogeny will be a useful tool for predicting the distribution of traits that may enhance its utility, and may lead to a better understanding of its evolution and ecology. Here we present the plastome of Coelastrum microporum . Our exemplar was isolated from Gull Lake, Michigan and the complete plastome as assembled was 169,961 bp in length. The plastome contained 104 genes of which 68 were protein-coding genes (CDSs), 27 tRNA genes and three rRNA genes. The GC content of the plastome was 31.2%. The maximum likelihood phylogeny suggested that C. microporum was the sister group to a clade of single exemplars of three other genera in the Scenedesmaceae ( Tetradesmus , Pectinodesmus and Coelastrella )., Competing Interests: The authors report that there is no conflict of interest involved., (© 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Cette étude fournit de nouvelles connaissances sur les préférences écologiques Pediastrum, plus c´est la premiere description detaillee des populations naturelles et des cultures au Mexique. Elle fournit des informations sur l'ultrastructure et les conditions environnementales de Pediastrum sensu lato dans en endroits dans le centre du pays. Ce genre (Hydrodictyaceae, Chlorophyceae) n'a pas une origine monophyletique plutot a ete divisé en cinq genres : Lacunastrum, Monactinus, Parapediastrum, Pseudopediastrum et Stauridium. Les spécimens étudiés ont été recueillies entre Octobre 2009 et Novembre 2013. Les microscopes optique et electronique ont revele la presence de sept especes. Parmi cellesci, Monactinus simplex, Pediastrum duplex, Pseudopediastrum boryanum et Stauridium tetras ont une distribution dans le monde entier. Au lieu de cela, Monactinus simplex var. echinulatum, M. simplex var. sturmii et Pediastrum simplex var. clathratum ont été enregistrées comme des taxa rares. La distribution des especes en examinant la litterature de 1841-2015 a signalé l'existence de 23 taxa dans 17 états du Mexique, où les états de Mexique, Veracruz et Michoacan avec plusieurs especes. L'analyse Canonicale des Correspondances a montre que les relations entre les especes et les conditions environnementales des taxons rares sont liées à des températures élevées, des sites bien oxygénés et des conditions eutrophes. This study gives new insights into ecological preferences of the Pediastrum genus as well as the first detailed description of its natural populations and cultures in Mexico. This artile provides information on the ultrastructure and environmental conditions of Pediastrum sensu lato at six locations in the center of Mexico. This genus (Hydrodictyaceae, Chlorophyceae) does not have a monophyletic origin; rather, it has been divided into the following five genera: Lacunastrum, Monactinus, Parapediastrum, Pseudopediastrum and Stauridium. The study specimens were collected between October 2009 and November 2013. Light and scanning electron microscopy revealed the presence of seven species. Of these, Monactinus simplex, Pediastrum duplex, Pseudopediastrum boryanum and Stauridium tetras have worldwide distribution. By contrast, Monactinus simplex var. echinulatum, M. simplex var. sturmii and Pediastrum simplex var. clathratum were found to be rare taxa. The species distribution as determined by literature review of articles from 1841 to 2015 registered the presence of 23 taxa in 17 Mexican states, namely, Mexico City, Veracruz and Michoacan which were the sites with the largest numbers of species. Canonical correspondence analyses showed that the relationships between the species and the environmental conditions of the rare taxa are related to well-oxygenated, high temperature and eutrophic conditions. [ABSTRACT FROM AUTHOR]

This article focuses on a detailed morphological and molecular analysis of the microscopic green alga Pediastrum alternans as it exhibits ambiguous morphology, questionable phylogenetic position and scattered distribution. The species, originally described from lakes close to the Baltic Sea in Denmark, was recently renamed Pseudopediastrum alternans based on rDNA sequencing of one culture from Namibia. In the present study, the African culture was morphologically and genetically compared with a culture identified as Ps. alternans from a coastal lake from northern Poland and a culture of Ps. boryanum var. longicorne from southern Poland. Conventional measurements, statistical and geometric morphometric analyses of the number of cells in coenobia, cell shape and size and wall ornamentation showed significant differences in the morphology of the three cultures. The analyses supported the phylogenetic distinction of the cultures based on rDNA and chloroplast DNA sequencing. Cultures of Pseudopediastrum alternans from Africa and Poland were not monophyletic. The African culture was moderately supported in a clade that could potentially represent a new species of Pseudopediastrum; whereas, the Polish culture formed a distinct lineage that was sister to some Ps. boryanum strains. The third culture, identified as Ps. boryanum var. longicorne, was nested within Ps. boryanum, as expected based on its morphology. Additional morphological comparison between the cultures and the iconotype showed that the Polish culture fits the description of Ps. alternans; whereas, the African one is so different from the iconotype that it cannot be called Ps. alternans. Analysis of plasticity of the Polish culture showed that its morphology is rather stable under varying nutrient and salinity conditions, and the culture cannot be misidentified as other Pseudopediastrum species. [ABSTRACT FROM AUTHOR]

Earlier and more recent history of the relationship between the desmid genera Acutodesmus and Tetradesmus (Sphaeropleales, Chlorophyta) is discussed. It is pointed out that current taxonomic treatments are using the name Acutodesmus (Hegewald) Tsarenko, which dates as a genus only from 2001. Taxonomic treatments are now including in Acutodesmus A. wisconsinensis, which is the type species of the earlier generic name Tetradesmus of G. M. Smith (1913). Because of the priority of Tetradesmus, ten taxa are transferred to that genus. [ABSTRACT FROM AUTHOR]

We characterized the complete sequence of the mitochondrial genome of the freshwater green algal strain YC001, known as 'Ettlia sp.', which is of great interest for biofuel production. The size of the mitogenome was 52,489 base pairs (bp), with 49.0% GC content. It consisted of 49 mitochondrial genes typical of the Chlorophyceae, including 16 protein-coding genes, 27 transfer RNA genes and six ribosomal RNA genes as well as three introns within cox1 (6832 bp), rnlA (1805 bp) and cob (1107 bp). We determined that YC001 is a species of Coelastrella on the basis of molecular phylogenetic analyses and microscopic observations. A unique feature of this mitogenome is the presence of three different types of inverted repeats between tmh and tml and between nadA and cox1 as well as the presence of orfl7555, and one additional copy of the trnM gene, all of which enable a comparison with an available sister taxon, Acutodesmus obliquus. [ABSTRACT FROM AUTHOR]

Background: The variability in gene organization and architecture of green algal mitochondrial genomes is only recently being studied on a finer taxonomic scale. Sequenced mt genomes from the chlorophycean orders Volvocales and Sphaeropleales exhibit considerable variation in size, content, and structure, even among closely related genera. However, sampling of mt genomes on a within-family scale is still poor and the sparsity of information precludes a thorough understanding of genome evolution in the green algae. Methods: Genomic DNA of representative taxa were sequenced on an Illumina HiSeq2500 to produce 2×100 bp paired reads, and mitochondrial genomes were assembled and annotated using Geneious v.6.1.5. Phylogenetic analysis of 13 protein-coding mitochondrial genes spanning the Sphaeropleales was performed. Results: This study presents one of the first within-family comparisons of mt genome diversity, and is the first to report complete mt genomes for the family Hydrodictyaceae (order Sphaeropleales). Four complete mt genomes representing three taxa and four phylogenetic groups, Stauridium tetras, Pseudopediastrum boryanum, and Pediastrum duplex, range in size from 37,723 to 53,560 bp. The size variability is primarily due to intergenic region expansion, and intron content is generally low compared with other mt genomes of Sphaeropleales. Conclusions: Certain gene rearrangements appear to follow a phylogenetic pattern, and with a more thorough taxon sampling genome-level sequence may be useful in resolving systematic conundrums that plague this morphologically diverse family. [ABSTRACT FROM AUTHOR]

A new species of the chlorophycean genus Desmodesmus, D. baconii, was described based upon analyses of the morphology of the coenobia and DNA sequences from the nuclear ribosomal 18S RNA gene and the internal transcribed spacer region. Desmodesmus baconii was unusual in that it possessed two rows of spines only on the terminal cells. This species was easily distinguished from other Desmodesmus taxa with two rows of spines by the point symmetry of the coenobia and the lack of rows of spines on median cells of four-celled coenobia. Spines tapered from prominent incurved spines near one pole to small spines at the opposite pole. Median cells and the pole of terminal cells opposite the large spines had two or three short spines. Cell sizes were slightly larger for two-celled (4.2-6.7 μm × 1.6-2.9 μrn) than for four-celled coenobia (3.2-6.5 μm × 1.2-4.5 μm). Results of analyses of DNA sequence data indicated that D. baconii, although a member of the monophyletic genus Desmodesmus, was not closely allied with any other Desmodesmus taxon. Desmodesmus baconii was isolated from hypereutrophic Lake Chicot in Arkansas, USA, and is not known from any other location [ABSTRACT FROM AUTHOR]

Five green algal taxa rarely occurring in the world were found in subalpine lakes of the High Tatra Mountains in Poland. These are Actinastrum gracillimum G.M. Sm. var. elongatum (G.M. Sm.) Fott, Monoraphidium tatrae (Hindák) Hindák, Pediastrum braunii Wartm. in Wartm. et Schenk, Scotiella tuberculata Bourr. var. tuberculata and Thelesphaera olivacea (Beck-Mannag.) Fott. The taxa are described and illustrated with light micrographs and drawings. A review of their distribution in the world is presented. [ABSTRACT FROM AUTHOR]

The Chlorophyceae (sensu Mattox and Stewart) is a morphologically diverse class of the Chlorophyta displaying biflagellate and quadriflagellate motile cells with varying configurations of the flagellar apparatus. Phylogenetic analyses of 18S rDNA data and combined 18S and 26S rDNA data from a broad range of chlorophycean taxa uncovered five major monophyletic groups (Chlamydomonadales, Sphaeropleales, Oedogoniales, Chaetophorales, and Chaetopeltidales) but could not resolve their branching order. To gain insight into the interrelationships of these groups, we analyzed multiple genes encoded by the chloroplast genomes of Chlamydomonas reinhardtii P. A. Dang. and Chlamydomonas moewusii Gerloff (Chlamydomonadales), Scenedesmus obliquus (Turpin) Kütz. (Sphaeropleales), Oedogonium cardiacum Wittr. (Oedogoniales), Stigeoclonium helveticum Vischer (Chaetophorales), and Floydiella terrestris (Groover et Hofstetter) Friedl et O’Kelly (Chaetopeltidales). The C. moewusii, Oedogonium, and Floydiella chloroplast DNAs were partly sequenced using a random strategy. Trees were reconstructed from nucleotide and amino acid data sets derived from 44 protein-coding genes of 11 chlorophytes and nine streptophytes as well as from 57 protein-coding genes of the six chlorophycean taxa. All best trees identified two robustly supported major lineages within the Chlorophyceae: a clade uniting the Chlamydomonadales and Sphaeropleales, and a clade uniting the Oedogoniales, Chaetophorales, and Chaetopeltidales (OCC clade). This dichotomy is independently supported by molecular signatures in chloroplast genes, such as insertions/deletions and the distribution of trans-spliced group II introns. Within the OCC clade, the sister relationship observed for the Chaetophorales and Chaetopeltidales is also strengthened by independent data. Character state reconstruction of basal body orientation allowed us to refine hypotheses regarding the evolution of the flagellar apparatus. [ABSTRACT FROM AUTHOR]

Ultrastructural analyses of the flagellar apparatus suggested that Sphaeroplea, Atractomorpha, the Hydrodictyaceae, and the Neochloridaceae, all of which produce biflagellate motile cells with directly opposed (DO) basal bodies, are allied in an order Sphaeropleales. Recent studies of 18S rDNA sequence data supported an alliance of the DO group, but no data from Sphaeroplea and its allies were included. This investigation presented a test of the phylogenetic hypothesis suggested by the flagellar apparatus evidence using sequence data from the nuclear-encoded small-subunit rDNA (18S) and large subunit rDNA (26S) genes, combined with additional taxon sampling. Results from phylogenetic analyses weakly supported monophyly of biflagellate DO taxa and indicated that pyrenoids with cytoplasmic invaginations are present in numerous distinct lineages. Analysis of both molecular data sets supported a class Chlorophyceae comprised of at least six major groups that generally correspond to currently recognized orders or families: Chaetophorales, Chae- topeltidales, Chlamydomonadales, Sphaeropleales, Sphaeropleaceae, and Oedogoniales. In addition, Cylindrocapsa, Elakatothrix, Treubaria, and Trochiscia formed a seventh chlorophycean clade that is new to science. This investigation demonstrated that the 26S rDNA gene provides more phylogenetic signal, per unit sequence, than the 18S rDNA gene and that combined analysis yields topologies with more robust support than independent analysis of either data set. [ABSTRACT FROM AUTHOR]

Komárek has recently reviewed the various species assigned to the green algal genus Neochloris Starr ( Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus, Ettlia. Watanabe & Floyd, unaware of Komárek's work, also reviewed the species of Neochloris and distributed them among three genera- Neochloris, Chlorococcopsis gen. nov., and Parietochloris gen. nov.-on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class. [ABSTRACT FROM AUTHOR]

RESUMO Os parques públicos de Goiânia apresentam importância socioambiental para a cidade, no entanto pouco se conhece sobre a sua qualidade e biodiversidade aquática. O presente estudo é focado nas Chlorophyceae e Trebouxiophyceae (Chlorophyta) em um lago de parque urbano localizado no município de Goiânia, GO, durante um curto período de chuva e de seca. As coletas foram realizadas semanalmente durante agosto de 2007 e janeiro de 2008, em três estações de amostragem, de acordo com as técnicas usuais para análises florísticas. Foram identificados 25 táxons infragenéricos: 16 Sphaeropleales, seis Chlorellales, um Chlamydomonales, um Chlorococcales e um táxon de Trebouxiophyceae de posição incerta. Pandorina morum, Lacunastrum gracillimum, Desmodesmus intermedius var. acutispinus e Pachycladella komarekii são registradas pela primeira vez para o Estado de Goiás.

Background: Comparative studies of chloroplast genomes (plastomes) across the Chlorophyceae are revealing dynamic patterns of size variation, gene content, and genome rearrangements. Phylogenomic analyses are improving resolution of relationships, and uncovering novel lineages as new plastomes continue to be characterized. To gain further insight into the evolution of the chlorophyte plastome and increase the number of representative plastomes for the Sphaeropleales, this study presents two fully sequenced plastomes from the green algal family Hydrodictyaceae (Sphaeropleales, Chlorophyceae), one from Hydrodictyon reticulatum and the other from Pediastrum duplex ., Methods: Genomic DNA from Hydrodictyon reticulatum and Pediastrum duplex was subjected to Illumina paired-end sequencing and the complete plastomes were assembled for each. Plastome size and gene content were characterized and compared with other plastomes from the Sphaeropleales. Homology searches using BLASTX were used to characterize introns and open reading frames (orfs) ≥ 300 bp. A phylogenetic analysis of gene order across the Sphaeropleales was performed., Results: The plastome of Hydrodictyon reticulatum is 225,641 bp and Pediastrum duplex is 232,554 bp. The plastome structure and gene order of H. reticulatum and P. duplex are more similar to each other than to other members of the Sphaeropleales. Numerous unique open reading frames are found in both plastomes and the plastome of P. duplex contains putative viral protein genes, not found in other Sphaeropleales plastomes. Gene order analyses support the monophyly of the Hydrodictyaceae and their sister relationship to the Neochloridaceae., Discussion: The complete plastomes of Hydrodictyon reticulatum and Pediastrum duplex , representing the largest of the Sphaeropleales sequenced thus far, once again highlight the variability in size, architecture, gene order and content across the Chlorophyceae. Novel intron insertion sites and unique orfs indicate recent, independent invasions into each plastome, a hypothesis testable with an expanded plastome investigation within the Hydrodictyaceae., Competing Interests: The authors declare there are no competing interests.