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The Oedogoniales comprises the genera Oedogonium, Oedocladium and Bulbochaete which include more than 600 described species. However, only two chloroplast genome sequences have been reported to date, and little is known about the evolutionary relationships between these genera or their infrageneric classification. This group is economically important in astaxanthin production and the energy sector. We examined four Oedocladium strains from different locations in China. One was identified as O. prescottii, and the morphology and molecular data for the other three strains suggested that they were O. carolinianum. Our chloroplast (cp) genome sequences of O. prescottii (FACHB-2452) and O. carolinianum (FACHB-2453) were compared with previously reported Oedogoniales cp genomes. The cp genome of O. carolinianum FACHB-2453 was of similar size, structure and composition to that of O. carolinianum UTEX LB 1686, apart from two missing group I introns in the genes psbA and psbD. O. prescottii showed more differences with regard to genome size, structure, number of genes and introns, and repeats than the other Oedogoniales cp genomes. The inverted repeats (IRs) region of the O. prescottii cp genome had a 10-kb contraction. Synteny analysis of the four cp genomes showed a high degree of syntenic conservation in general; however, some structural variation at genus level was observed in Oedocladium. In phylogenetic analyses of Oedocladium using sequences of 18S rDNA, ITS and 59 cp protein-coding genes, species were placed on two separate branches within the Oedogonium clade, indicating that Oedocladium is a paraphyletic group. [ABSTRACT FROM AUTHOR]

Members of the Watanabea clade of Trebouxiophyceae are genetically diverse and widely distributed in all kinds of habitats, especially in most terrestrial habitats. Ten new strains of terrestrial algae isolated from the tropical rainforest in China, and four published strains were investigated in this study. Morphological observation and molecular phylogenetic analyses based on the 18S, ITS, rbcL, and tufA genes were used to identify the new strains. Four previously described species were reinvestigated to supplement molecular data and autospores' morphological photographs. The phylogenetic analyses based on 18S only, the concatenated dataset of 18S and ITS, as well as the concatenated dataset of rbcL and tufA, showed the same phylogenetic positions and relationships of these new strains. According to the phylogenetic analysis and morphological comparisons results, we described these 10 strains as four new members within the Watanabea clade, Polulichloris yunnanensis sp. nov., Polulichloris ovale sp. nov., Massjukichlorella orientale sp. nov., and Massjukichlorella minus sp. nov., and two known species, Massjukichlorella epiphytica, and Mysteriochloris nanningensis. Additionally, we provide strong evidence proving that Phyllosiphon, Mysteriochloris, Polulichloris, and Desertella all reproduce through unequal sized autospores. [ABSTRACT FROM AUTHOR]

Two unidentified foliicolous algal strains were isolated from living Ficus leaves in a tropical rainforest of China. Morphological, ultrastructural, and molecular phylogenetic investigations of these strains indicated that they differ from each other but cluster together and represent a new lineage of Trebouxiophyceae in the Choricystis/Botryococcus clade. These strains had similar morphologies with solitary, fusiform, and slightly asymmetrical vegetative cells, a basal stalk, and smooth cell walls. Cells contained a single parietal chloroplast with a pyrenoid surrounded by several starch sheaths and penetrating thylakoids. Asexual reproduction occurred in both strains through the splitting of the mother cell wall into two autospores. Phylogenetic analysis based on 18S, ITS and rbcL showed the two strains as a distinct branch in the Choricystis/Botryococcus clade of the Trebouxiophyceae. Here, we describe the two strains as the new genus, Obliquicauda gen. nov., and two new species, Obliquicauda inflata sp. nov. and Obliquicauda apiculata sp. nov. [ABSTRACT FROM AUTHOR]

The colonial volvocine algae span the full range of organizational complexity, from four-celled species to multicellular species, and this group of algae is often used for the study of evolution. In recent years, many organelle genomes have been sequenced using the application of next generation sequencing technology; however, only a few organelle genomes have been reported in colonial volvocine algae. In this study, we determined the organelle genomes of Eudorina elegans and Eudorina cylindrica and analysed the organelle genome size, structure and gene content between these volvocine species. This provided useful information to help us understand the composition of colonial volvocine organelle genomes. Based on the chloroplast genome protein-coding genes, we conducted a phylogenomics analysis of the volvocine algae. The result revealed an unexpected phylogenetic relationship, namely, E. elegans is more closely related to Pleodorina starrii than to E. cylindrica. The substitution rate of volvocine algae was then calculated based on organelle genome protein-coding genes; our analysis suggested the possibility that the two Eudorina species may be under similar evolutionary pressure. Lastly, the synteny analysis of the mitochondrial genome showed that gene arrangements and contents are highly conserved in the family Volvocaceae, and the synteny analysis of the chloroplast genome indicated that the genus Eudorina may have experienced genomic changes. [ABSTRACT FROM AUTHOR]

Abstract: The Parachlorella clade was put forward as a group within the family Chlorellaceae in 2004. Recent molecular analyses have revealed that Dictyosphaerium morphotype algae form several independent lineages within the Parachlorella clade, and new genera and species have been established. In this study, we focus on the diversity of Dictyosphaerium morphotype algae within the Parachlorella clade, based on 42 strains from China. We used combined analyses of morphology and molecular data based on SSU and internal transcribed spacer region (ITS) rDNA sequences to characterize these algae. In addition, the secondary structure of ITS2 was compared to delineate new lineages. Our results revealed high phylogenic diversity of Dictyosphaerium morphotype algae, and we describe five distinct lineages. We examined the morphological features of these five lineages, and morphological differences are difficult to find compared with other Dictyosphaerium morphotype algae. The five distinct lineages were not described as new genera currently. We lastly discuss the taxonomic problems regarding the Dictyosphaerium morphotype within the Parachlorella clade, and possible solutions are considered. [ABSTRACT FROM AUTHOR]