Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Life habit: lichenized Thallus: crustose, areolate, 20-50 mm in diam., attached by the whole lower surface; prothallus: usually evident, black, marginal and between the areoles areoles: rounded to angular, contiguous surface: brown to dark brown, plane, smooth, without isidia or soredia photobiont: primary one a chlorococcoid green alga, secondary one absent Ascomata: apothecial, indistinct, orbicular, immersed, 0.1-0.2 mm in diam. disc: black, dull, plane, epruinose; margin: indistinct exciple: grayish brown peripherally, hyaline internally, up to 90 µm wide marginally, with c. 5 µm wide hyphae, with photobiont cells epihymenium: gray-green to yellowish brown, 7-10 µm thick hymenium: hyaline, 20-40 µm tall, I-; paraphyses: distinctly branched and anastomosing, c. 2 µm wide below, (2.5-)3-4 µm wide apically; hypothecium: hyaline or brownish yellow asci: lecanoral, with a thickened wall apically, tholus amyloid and with wide, axial body divergent towards apex, 30-40 x 10-11 µm, 8-spored ascospores: hyaline, simple, ellipsoid, 7-14 µm x 3-6 µm; wall: thin and smooth Conidiomata: not seen Spot tests: cortex and medulla K-, C-, KC-, P- Secondary metabolites: an unknown ß-orcinol depsidones. Substrate: non-calciferous rock in high mountains Geography: throughout Europe, southwestern North America, Japan, and Australasia Sonoran distribution: Arizona and Sonora. Notes: Clauzadeana macula is characterized by its small, immersed apothecia, its hyaline hypothecium and short hymenium. Due to its small size, it is often overlooked.