Cyanobacteria have a number of properties, such as the ability to photosynthesize and fix nitrogen, which contribute to their survival in the harsh climatic conditions of the White Sea coast, which makes them attractive to organisms of various kingdoms for creating associations. In this paper, we studied such cohabitations with the moss Hylocomium splendens and the three-component lichen Nephroma arcticum. Using light and scanning electron microscopy, elongated ellipsoid, less often spherical, primordia of cyanobacteria were found on the surface of moss shoots. For the lichen, the location of cyanobacteria in cephalodia inside the thallus is shown, and for the first time, microscopic observation revealed the division of the phycobiont layer into upper and lower parts. In both types of associations, mucopolysaccharides were noted using ruthenium red staining. Genetic diversity analysis of moss- and lichen-associated cyanobacteria based on the V4 fragment of the 16S rRNA gene revealed the presence of representatives of the families Nostocaceae, Tolypotrichaceae, and Leptolyngbyaceae on the moss surface, while only representatives of the family Nostocaceae were noted for the lichen. Six amplicone sequence variants of Nostoc sp. were noted for cyanobacterial cohabitations with moss, while only one was found for the lichen, and it was found among moss associates. The present study suggests that long-term cohabitation of cyanobacteria with fungi in lichen thallus serves as a reservoir of symbiotic cyanobacterial strains capable of infecting moss shoots. It has been established that identical cyanobacterium may be present in cohabitation with mosses and fungi in the same biotope. Keywords: closely related cyanobionts, cyanobacterial localization, Hylocomium splendens, moss-cyanobacterium association, Nephroma arcticum, 16S rRNA gene metabarcoding.