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: inconspicuous or immersed, indeterminate Ascomata: 0.6-2.5 x 0.1-0.3 mm, simple or branched, adnate, scattered or aggregated, with a thin slit-line disc, becoming slightly widened when old, epruinose exciple: closed, 25-40 µm laterally, 40-70 µm at base, K- hymenium: 55-75 µm, I+ reddish; subhymenium: pale brown, 25-40 µm, I+ reddish; paraphysoids: to 1 µm wide asci: cylindric-clavate, 45-50 x 11-13 µm (Vulgatatype) ascospores: fusiform to somewhat clavate, 15-18 x 4-4.5(-5) µm, 3(-4)-septate, straight to slightly curved, with a thin gelatinous sheath, wall thin and not swollen at septa (Calcarea-type) Pycnidia: immersed to subimmersed conidia: 5-6 x 0.8-1 µm, straight Spot tests: thallus K-, C-, KC-, P- Secondary metabolites: none detected. Substrate and ecology: on bark and wood World distribution: coastal, central California Sonoran distribution: not yet known but expected in the northern part of the range. Notes: The shape and size of its ascomata and ascospores suggest close affinities with O. atra, but O. erosa differs in having a K- exciple and asci of the vulgata-type.