Family Scenedesmaceae Research Articles

Chodatodesmus australis sp. nov. (Scenedesmaceae, Chlorophyta) from Antarctica, with the emended description of the genus Chodatodesmus, and circumscription of Flechtneria rotunda gen. et sp. nov.

The family Scenedesmaceae is a taxonomically complicated group due to its simple morphology, high phenotypic plasticity, and the presence of cryptic taxa. Over the years several taxonomic revisions, based on molecular data, affected the family. Here, we describe a new scenedesmacean species from Antarctica, Chodatodesmus australis, based on phylogenetic analyses of data from nuclear (ITS2 spacer, 18S rDNA), and plastid (rbcL, tufA) markers. Morphological (LM and SEM) and ultrastructural (TEM) observations, carried out both on the holotype of C.australis and on the generitype of Chodatodesmus, allow us to emend the original generic description of this genus. Our molecular and phylogenetic data also reveal the existence of a new monotypic genus, Flechtneria, inside the family Scenedesmaceae and lead to the taxonomic reassignment of some microalgal strains available in International Culture Collections to new taxa. Of the considered genomic regions, the tufA gene was the easiest to amplify and sequence and it showed the highest phylogenetic signal, even if the number of sequences already available for this marker in the public databases was considerably lower than for the other chosen loci. The rbcL gene also provided good phylogenetic signal, but its amplification and sequencing were generally more problematic. The nuclear markers gave lower phylogenetic signals, but the 18S rDNA allowed distinction at the genus level and the ITS2 spacer had the advantage that secondary structures could be considered in the analyses. The use of more than one molecular locus is suggested to obtain reliable results in the characterization of scenedesmacean strains.

Scenedesmaceae (Chlorophyta, Chlorophyceae) de duas áreas do Pantanal dos Marimbus (Baiano e Remanso), Chapada Diamantina, Estado da Bahia, Brasil

RESUMO de duas áreas do Pantanal dos Marimbus (Baiano e Remanso), Chapada Diamantina, Estado da Bahia, Brasil). Este estudo trata do estudo taxonômico da família Scenedesmaceae do Pantanal dos Marimbus, Área de Proteção Ambiental Marimbus-Iraquara, Chapada Diamantina, Bahia, Brasil. As amostras provenientes do perifíton e do plâncton foram coletadas em duas áreas do Pantanal dos Marimbus (Baiano e Remanso), durante o período seco (abril, junho e agosto de 2011) e o período chuvoso (outubro, dezembro de 2011 e fevereiro de 2012). São descritos 27 táxons, dos quais 18 são adições a flora ficológica da Bahia.

Characterization of five fresh water microalgae with potential for biodiesel production

Microalgae biodiesel feedstocks have been investigated by numerous research groups to overcome dependence on fossil fuels. This study describes a detailed characterization of five freshwater microalgae strains of the family Scenedesmaceae, based on cell wall ultrastructure, ITS-2 sequence and secondary structure analysis, as well as the estimation of biodiesel properties from fatty acids produced before and after N-limitation. Characterization permitted the reclassification of SCRE-1 and SCRE-2 strains into the subgenus Scenedesmus; DSRE-1 and DSRE-2 strains into the subgenus Desmodesmus; and CORE-1 strain into the genus Coelastrum. Transesterification of fatty acids of the five strains was performed before and after N-limitation, and seven important biodiesel quality parameters were predicted by applying selected correlations. These parameters were then compared to the corresponding specifications in the American and European biodiesel standards. N-limitation promoted higher yields of biomass (up to 3.5 times) and lipids (up to 4.1 times) in all strains under study. Moreover, it was found that SCRE-2 was the only biodiesel that met all estimated parameters of the more stringent European standard before N-limitation. This was also true for DSRE-1 and DSRE-2 biodiesels after limitation, with the exception of their oxidative stability parameter, whose values met the limit of the American but not the European standard.

Classification of crucigenoid algae: phylogenetic position of the reinstated genus Lemmermannia, Tetrastrum spp. Crucigenia tetrapedia, and C. lauterbornii (Trebouxiophyceae, Chlorophyta)(1).

The subfamily Crucigenioideae was traditionally classified within the well-characterized family Scenedesmaceae (Chlorophyceae). Several morpho-logical revisions and questionable taxonomic changes hampered the correct classification of crucigenoid species resulting in a high number of synonymous genera. We used a molecular approach to determine the phylogenetic position of several Tetrastrum and Crucigenia species. The molecular results were correlated with morphological and ontogenetic characters. Phylogenetic analyses of the SSU rDNA gene resolved the position of Tetrastrum heteracanthum and T.staurogeniaeforme as a new lineage within the Oocystis clade of the Trebouxiophyceae. Crucigenia tetrapedia, T.triangulare, T.punctatum, and T.komarekii were shown to be closely related to Botryococcus (Trebouxiophyceae) and were transferred to Lemmer-mannia. Crucigenia lauterbornii was not closely related to the other Crucigenia strains, but was recovered within the Chlorella clade of the Trebouxiophyceae.

Criptógamos do Parque Estadual das Fontes do Ipiranga, São Paulo, SP: algas, 30: Chlorophyceae (família Scenedesmaceae)

Levantamento florístico dos representantes da família Scenedesmaceae (Chlorophyceae) do Parque Estadual das Fontes do Ipiranga, São Paulo, Brasil. Doze gêneros (Crucigenia, Crucigeniella, Desmodesmus, Didymogenes, Dimorphococcus, Pseudodidymocystis, Pseudotetrastrum, Scenedesmus, Tetrachlorella, Tetrallantos, Tetrastrum e Westella), 47 espécies e 11 variedades que não são as típicas de suas respectivas espécies foram identificadas. O gênero representado pelo maior número de táxons foi Desmodesmus, com 16 espécies e sete variedades que não são as típicas de suas respectivas espécies. Vem a seguir Scenedesmus com 14 espécies e quatro variedades igualmente não típicas. As espécies que ocorreram no maior número de ambientes foram: Desmodesmus communis, D. denticulatus var. linearis, D. intermedius var. acutispinus, Pseudodidymocystis fina, Scenedesmus obliquus var. dimorphus, S. acunae e S. obtusus, por ocorrerem em três localidades cada uma.

Hylodesmus singaporensis gen. et sp. nov., a new autosporic subaerial green alga (Scenedesmaceae, Chlorophyta) from Singapore

The algal flora of subaerial habitats in the tropics remains largely unexplored, despite the fact that it potentially encompasses a wealth of new evolutionary diversity. Here we present a detailed morphological and molecular characterization of an autosporic coccoid green alga isolated from decaying wood in a natural forest in Singapore. Depending on culture conditions, this alga formed globular to irregularly oval solitary cells. Autosporulation was the only mode of reproduction observed. The cell periphery was filled with numerous vacuoles, and a single parietal chloroplast contained a conspicuous pyrenoid surrounded by a bipartite starch envelope. The cell wall was composed of a thick inner layer and a thin trilaminar outer layer, and the cell surface was ornamented with a few delicate ribs. Phylogenetic analyses of 18S rRNA gene sequences placed our strain in the family Scenedesmaceae (Sphaeropleales, Chlorophyceae) as a strongly supported sister branch of the genus Desmodesmus. Analyses of an alternative phylogenetic marker widely used for the Scenedesmaceae, the ITS2 region, confirmed that the strain is distinct from any scenedesmacean alga sequenced to date, but is related to the genus Desmodesmus, despite lacking the defining phenotypic features of Desmodesmus (cell wall with four sporopolleninic layers ornamented with peculiar submicroscopic structures). Collectively, our results establish that we identified a novel, previously undocumented, evolutionary lineage of scenedesmacean algae necessitating its description as a new species in a new genus. We propose it be named Hylodesmus singaporensis gen. et sp. nov. A cryopreserved holotype specimen has been deposited into the Culture Collection of Algae of Charles University in Prague, Czech Republic (CAUP) as CAUP C-H8001.

Pectodictyon, a New Genus in the Family Scenedesmaceae

Pectodictyon, a New Genus in the Family Scenedesmaceae

Coronastrum: A New Genus of Algae in the Family Scenedesmaceae

American Journal of BotanyVolume 25, Issue 9 p. 692-694 Article CORONASTRUM: A NEW GENUS OF ALGAE IN THE FAMILY SCENEDESMACEAE R. H. Thompson, R. H. Thompson Department of Botany, University of Kansas, Lawrence, KansasSearch for more papers by this author R. H. Thompson, R. H. Thompson Department of Botany, University of Kansas, Lawrence, KansasSearch for more papers by this author First published: 01 November 1938 https://doi.org/10.1002/j.1537-2197.1938.tb12836.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume25, Issue9November 1938Pages 692-694 RelatedInformation