Systematics and evolutionary history of pyrenoid-bearing taxa in brown algae (Phaeophyceae)

In brown algae (Phaeophyceae), only a few taxa are reported to have plastids containing pyrenoids and this character has often been used for systematic delineation. Members of the Ectocarpales display large, stalked and exserted pyrenoids in their plastids, whereas the Scytothamnales, as well as the genera Asterocladon, Asteronema and Bachelotia, exhibit plastids arranged in a stellate configuration with pyrenoids embedded in the plastid stroma. The evolution of plastid characters has remained difficult to establish, especially because of a persistent lack of resolution in brown algal molecular phylogenies. Here, we generated a seven-locus dataset for a species-rich taxon sampling, to reassess phylogenetic relationships of pyrenoid-bearing brown algal taxa. Within the Ectocarpales, the relationships among families are clarified. The minute chordariacean genus Herponema is assigned to the family Acinetosporaceae. The systematic positions of two enigmatic genera are revised: Chordariopsis is assigned to the...