Noctebacteria

Noctebacteria are a monotypic genus of cyanobacteria found in Antarctica. They have both marine and freshwater subspecies. They also have a few terrestrial subspecies. They can only be found in deep water and lake bottoms in the sunny winter but they can be seen everywhere in the dark summer. 

They evolved from the Prochlorococcus genus. Prochlorococcus use sulfur instead of phosphorus to survive in nutrient-poor environments. Luckily for them the thawed Antarctica is full of sulfur from the glacial melt and Holocene extinction. So they migrated from the open ocean into the surface waters of Antarctica

Noctebacteria are built for low light due to their deep sea origins. They have adapted to the Antarctic cold and low light by developing the ability to absorb the light from the aurora australis. The most common colors from the aurora australis are red and green. The chlorophyll molecule found exclusively in noctebacteria, chlorophyll g, absorbs red and green wavelengths. The light reflected is blue-violet, making the algae appear a dark blue.