During the study of the lichen biota of Sakhalin Island, Arthonia phaeobaea was identified basing of morphological and anatomical data. This is the first record of this rare saxicolous coastal lichen in Asia and Russia; the species was previously recorded only in Central and Northern Europe (including Arctic) and North America. The species is characterized by its thin, smooth, brown-gray continuous thallus without lichen compounds, usually with numerous black pycnidia and small, black, rounded to elongated, weakly convex apothecia, dark brown epithecium K–, pale hypothecium, colorless, (2)3–4 cross-septate ascospores constricted centrally and usually with unequal cells, hyaline conidia, narrowly ellipsoid or oblong. The maritime distribution of the species has been noted. The differences from other coastal saxicolous Arthonia species in a global scale, as well as saxicolous Arthonia, known in Russia, are discussed. Keywords: biogeography, coastal lichens, new records, Russian Far East, Sakhalin Island.