Life habit: lichenicolous, commensalistic or parasitic, non-lichenized Ascomata: when young, roundish, sub-spherical; upper sterile stromatic layer soon breaking along irregular slits giving the ascoma a verruculose appearance, 0.4-0.9 mm in diam.; mature ascomata regularly appearing aggregated in groups reaching 3(-4) mm in diam., as a result of concentric growth of one single ascoma in a later stage of development, epruinose exciple: closed, 30-40 µm laterally, 40-60 µm at base, K- hymenium: hyaline, pale brown to dark purplish brown, 110-120 µm, I+ persistent blue in upper and lower part, middle part sometimes I+ reddish only; subhymenium: pale brown, 20-30 µm; paraphysoids: 2-2.5 µm, apically indistinctly swollen asci: clavate, (4-)6(-8)-spored, 70-90 x 20-24 µm (Varia-type) ascospores: ellipsoid to oblong-ovoid, with ends rounded, 21-27(-29) x (7-)8-10 µm, 3-septate, straight, constricted at septa, surrounded by a thin gelatinous sheath, soon becoming covered in brownish granular warts (Parasitica-type) Pycnidia: immersed to subimmersed conidia: (5-)6-7 x 1.5(-2) µm, straight. Host and ecology: commensalistic or parasitic on thallus of corticolous Pertusaria species, including P. amara, P. epixantha, P. exalbescens and P. velata, and on Ochrolechia species, including O. androgyna and O. trochophora; in oak, pine, and shrub communities World distribution: North America, Europe, Canary Islands Sonoran distribution: southern California. Notes: This species is easily identified by its aggregated mature ascomata on host lichens of the genera Ochrolechia and Pertusaria, and the size of the 3-septate ascospores. Closely related lichenicolous species are O. glaucomaria which differs in having smaller ascomata (0.2-0.4 mm), 3-4-septate ascospores and a different host genus (Lecanora); Opegrapha pulvinata Rehm., known to occur on saxicolous members of the Verrucariales, has slightly smaller ascospores [up to 24(-26) x 7(-8) µm] which are pigmented in the spore wall, not in the perispore.