PSEUDONEOCHLORIS MARINA(CHLOROPHYTA), A NEW COCCOID ULVOPHYCEAN ALGA, AND ITS PHYLOGENETIC POSITION INFERRED FROM MORPHOLOGICAL AND MOLECULAR DATA

Abstract

Ultrastructural and molecular sequence data were used to assess the phylogenetic position of the coccoid green alga deposited in the culture collection of the University of Texas at Austin under the name of Neochloris sp. (1445). This alga has uninucleate vegetative cells and a parietal chloroplast with pyrenoids; it reproduces by forming naked biflagellate zoospores. Electron microscopy revealed that zoospores have basal bodies displaced in the counterclockwise absolute orientation and overlapped at their proximal ends. Four microtubular rootlets numbering 2 and 2/1 are alternatively arranged in a cruciate pattern. A system I fiber extends beneath each d rootlet and a system II fiber (rhizoplast) originates from each basal body and extends peripherally along each d rootlet. These features differ substantially from those of the three genera, Ettlia (Komárek) Deason et al., Neochloris (Starr) Deason et al., and Parietochloris Watanabe et Floyd, all of which were previously accommodated in the single genus Neochloris Starr. Sequence data from the nuclear small subunit ribosomal RNA gene were obtained and compared with published green algal sequences. Results from the ultrastructural and sequence data support the placement of Neochloris sp. (The Culture Collection of Algae at the University of Texas at Austin [UTEX] no. 1445) in the Ulvophyceae. This isolate is described as Pseudoneochloris marina, gen. et sp. nov. in the Ulotrichales, Ulvophyceae.

THE GREEN ALGAL GENUSCLONIOPHORAREPRESENTS A NOVEL LINEAGE IN THE ULVALES: A PROPOSAL FOR CLONIOPHORACEAE FAM. NOV.1

“…traversing thylakoids, as do many members of Ulvales (Hori 1973, Lokhorst and Star 1980, Watanabe et al 2000; this type of pyrenoid is absent from Chaetophorales (Lokhorst et al 1984). Phylogenetic analyses do not reveal affinity of Cloniophora specimens to any currently recognized ulvalean family for which DNA sequences are available.…”

PHYLOGENETIC RELATIONSHIPS AMONG STREPTOPHYTES AS INFERRED FROM CHLOROPLAST SMALL AND LARGE SUBUNIT rRNA GENE SEQUENCES1

“…Low resolution of these classes has proved to be a recurrent feature of phylogenetic reconstructions based on nuclear SSU rDNA sequences (e.g. Watanabe et al 2000); however, unlike the latter sequences, the combined chloroplast SSU and LSU rDNA sequences strongly support the monophyly of the Streptophyta and Chlorophyta. Resolution of all green plant lineages will require the analysis of additional gene markers and perhaps of complete organelle genome sequences; moreover, structural characteristics of organelle genomes such as gene order and intron content may prove to be helpful.…”

Phylogeny and Molecular Evolution of the Green Algae

“…For example, strains conforming to the morphological circumscription of the genera Neochloris, Characium and Planophila have been found in all three classes (Watanabe & Floyd, 1989;Lewis et al, 1992;Watanabe et al, 2000;Friedl & O'Kelly, 2002). Similarly, species of the coccoid genus Chlorococcum and the filamentous genus Uronema were present in the Chlorophyceae as well as the Ulvophyceae (Watanabe et al, 2001;Krienitz et al, 2003;Leliaert et al, 2009a).…”