Further browsing, and I ran across this paper (pdf) identifying Pandora Viruses as Phycodnaviruses that infect phytoplankton.
N. Yutin and E. V. Koonin. Pandoraviruses are highly derived phycodnaviruses. DNA,
Another paper provides a glimpse into Phycodnaviruses as tiny giants that rule the world.
[published on the Plant Pathology Commons.]