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Cephaleuros is a subaerial green alga widely distributed in tropical and subtropical regions. In this study, we investigated the taxonomy of Cephaleuros in southern China. Eight morphospecies (C. virescens, C. karstenii, C. expansus, C. drouetii, C. diffusus, C. tumidae-setae, C. lagerheimii and C. parasiticus) were identified according to previous descriptions, among which C. karstenii was the most frequently recorded. Subsequently, molecular phylogeny of Cephaleuros was inferred from 18S rDNA, ITS rDNA, 28S rDNA and rbcL sequences. Cephaleuros was subdivided into nine clades based on ITS analysis, which were recovered in phylogenies of two concatenated datasets (18S+ITS+28S and 18S+ITS+28S+rbcL). Molecular analyses revealed that Cephaleuros was composed of two main lineages, with one lineage comprising mostly samples of C. karstenii and C. virescens and the other comprising other species. The molecular phylogenies were not congruent with conventional morphological classifications, although some clades were distinguished by one or more diagnostic features. While the morphological features used to distinguish Cephaleuros spp were not reliable, the rbcL gene proved to be a good marker for identification of Cephaleuros. The ITS2 secondary structure prediction model showed that Cephaleuros spp have one ring structure with four helices, with Helix III being the longest without a branch in clades 3, 5 and 8. The present study represents the most detailed taxonomic assessment of Cephaleuros available to date. Further taxonomic research incorporating samples from the type locality is necessary for the reassessment of C. virescens. [ABSTRACT FROM AUTHOR]

The green algal genus Oncosaccus, endemic to China, has previously been classified in Chlamydomondales (Chlorophyceae). In the present study, two green algal specimens from west China were identified as Oncosaccus tetrasporoides due to their unique colonial form with numerous cells embedded in a thick gelatinous envelope without perforations and pseudocilia. Molecular data from two nuclear loci (18S rDNA and ITS) were used to test the hypothesised membership of this taxon. The molecular data clearly showed that Oncosaccus did not have close affinities to the Chlamydomondales, but instead belonged to the order Chaetopeltidales in the family Chaetopeltidaceae, and had a close relationship with Chaetopeltis and Pseudulvella. The ultrastructure of Oncosaccus tetrasporoides resembled Chaetopeltis and Pseudulvella, and adjacent cells lacked plasmodesmata, and the pyrenoid matrix was traversed by a cytoplasmic channel instead of the thylakoid membrane were present. This morphology supported the molecular data and confirmed this group's placement in the Chaetopeltidales. The present study expanded our understanding of the morphological features of green algae, particularly those of the poorly studied Chaetopeltidales. Nonetheless, a phylogenetic re-evaluation based on large samples in conjunction with molecular analyses is needed. [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]