Data from: Organellar phylogenomics inform systematics in the green algal family Hydrodictyaceae (Chlorophyceae) and provide clues to the complex evolutionary history of plastid genomes in the green algal Tree of Life.

Premise of the study: Phylogenomic analyses across the green algae are
resolving relationships at the class, order and family levels, and
highlighting dynamic patterns of evolution in organellar genomes. Here we
present a within-family phylogenomic study to resolve genera and species
relationships in the family Hydrodictyaceae (Chlorophyceae), for which
poor resolution in previous phylogenetic studies, along with divergent
morphological traits, have precluded taxonomic revisions. Methods:
Complete plastome sequences and mitochondrial protein-coding gene
sequences were acquired from representatives of the Hydrodictyaceae using
Next-Generation sequencing methods. Plastomes were characterized and gene
order and content were compared with plastomes spanning the
Sphaeropleales. Single-gene and concatenated-gene phylogenetic analyses of
plastid and mitochondrial genes were performed. Key results: The
Hydrodictyaceae contain the largest sphaeroplealean plastomes thus far
fully sequenced. Conservation of plastome gene order within
Hydrodictyaceae is striking compared with more dynamic patterns revealed
across Sphaeropleales. Phylogenetic analyses resolve Hydrodictyon sister
to a monophyletic Pediastrum, though the morphologically distinct P.
angulosum and P. duplex continue to be polyphyletic. Analyses of plastid
data supported the neochloridacean genus Chlorotetraëdron as sister to
Hydrodictyaceae, while conflicting signal was found in the mitochondrial
data. Conclusions: A phylogenomic approach resolved within-family
relationships not obtainable with previous phylogenetic analyses. Denser
taxon sampling across Sphaeropleales is necessary to capture patterns in
plastome evolution, and further taxa and studies are needed to fully
resolve sister lineage to Hydrodictyaceae and polyphyly of Pediastrum
angulosum and P. duplex.