Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Life habit: lichenized Thallus: thin, smooth, continuous surface: whitish, mat Ascomata: lirelliform, straight to often flexuous, immersed to erumpent, 0.5-3(-4) x 0.2-0.3 mm, simple, more rarely branched, scattered or contiguous; disc a slit or narrowly exposed, often covered by a very thin layer of whitish pruina exciple: widely open below the hymenium, dark brown, K+ olivaceous, 25-60 µm wide hymenium: 110-140 µm tall, I+ red; epihymenium pale brown; hypothecium pale to dark brown, 5-18 µm; paraphysoids richly branched, anastomosed, 1-1.5 µm wide asci: clavate to cylindric-clavate, 8-spored, 80-110 x 18-21 µm (between Varia-type and Vulgata-type) ascospores: oblong to elongate-fusiform, 28-40 x (4-)5-6.5(-7) µm, 8-9-septate, hyaline, becoming dark brown when over-mature probably due to a pigmentation of the wall (septa darker); perispore hyaline, 1.5 µm wide Pycnidia: not observed Spot tests: thallus P-, K-, KC-, C-, UV- Secondary metabolites: none detected. Substrate and ecology: epiphytic in a mangrove World distribution: Africa (Tanzania) and Mexico Sonoran distribution: Baja California Sur (one locality W of Ciudad Constitucion). Notes: The description above is based on the Sonoran specimen. Opegrapha graphidiza Nyl. is very close to O. subgraphidiza and differs mainly by the I+ persistently blue reaction of the hymenium. The external appearance of those species reminds the genus Graphis. Further studies on this species group, mainly present in tropical areas, are required.