Three new terms are here proposed […]. They are: (1) ‘phycobiont’, applicable to an alga in association with a fungus in the formation of a lichen […]. Phycobiont may also be applied to the algae associated with Cycas, Gunnera, Blasia, etc.
Scott, G.D. (1957). Lichen terminology. Nature 179, 486-487: 486; 487.
the term phycobiont should no longer be applied to blue-green symbionts since the combining from “phyco-” refers to algae which in this case is inappropriate. I propose the following terminology to solve this problem: Photosynthetic symbionts of lichens should together be referred to as photobionts (antonym is mycobionts); the blue-green symbionts should be renamed cyanobionts or bactobionts; the green algal and other algal symbionts should continue to be referred to as phycobionts.
Ahmadjian, V. (1982). Holobionts have more parts. International Lichenological Newsletter 15(2), 19.