[Diploschistes actinostoma var. caesioplumbeus (Nyl.) J. Steiner, more]
Thallus: rimose-areolate; areoles: 0.4-1.5 mm in diam., plane, thin or thick upper surface: gray to dark gray, smooth, shiny or dull, epruinose Ascomata: perithecioid, immersed, up to 1.6 mm in diam., disc: blackish, plane; proper exciple: up to 70 Ám thick; hymenium: 130-170 Ám high asci: subclavate, 4-8-spored ascospores: muriform, brown, broadly ellipsoid, 28-45 x 12-25 Ám; transverse septa 4-9, longitudinal septa 2-5 per transverse segment Pycnidia: not seen Spot tests: K-, C+ red, KC-, P-, UV- Secondary metabolites: lecanoric acid (major) and diploschistesic and orsellinic acids (both minor). Substrate and ecology: on siliceous rocks World distribution: temperate Europe, Mediterranean area, and western North America Sonoran distribution: locally abundant in mountainous areas of Arizona, Baja California and Baja California Sur, California, Chihuahua, Sinaloa and Sonora at 650-2300 m, also occurring at the coast in Baja California and California. Notes: Diploschistes caesioplumbeus is characterized by the relatively large ascospores, the perithecioid ascomata, and the dark grayish thallus. It may be confused with the morphologically similar D. actinostomus which has smaller spores.