The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of unicellular algae found in freshwater and moist terrestrial environments,[1][2] less common today than they were during the Proterozoic.
[1] Along with red algae[1] and cyanobacteria, they harvest light via phycobilisomes, structures consisting largely of phycobiliproteins.
Together with red algae and Viridiplantae (green algae and land plants), glaucophytes form the Archaeplastida – a group of plastid-containing organisms that may share a unique common ancestor that established an endosymbiotic association with a cyanobacterium.
[4] The internal phylogeny of the glaucophytes and the number of genera and species varies considerably among taxonomic sources.
[4] As of March 2022[update], AlgaeBase divided glaucophytes into only two groups, placing Cyanophora in Glaucocystales rather than Cyanophorales (however the entry was dated 2011).