Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life habit: lichenized Thallus: crustose, placodioid, subfruticose, gelatinous when wet surface: blackish, smooth or uneven, sometimes granulose anatomy: ecorticate, homoiomerous, fan-shaped or paraplectenchymatous hyphal arrangement photobionts: primary one a filamentous (Rivulariaceae) or chroococcoid cyanobacterium, secondary photobiont absent Ascomata: apothecial, laminal on thallus or terminal, orbicular, immersed to sessile, margin indistinct to prominent, with thin thalloid rim, sometimes evanescent ontogeny: hemiangiocarpous, forming pycnoascocarps from ascogonia beneath pycnidia ascoma anatomy: exciple: hyaline, faintly yellowish-brown to brownish; epithecium: brownish yellow; hypothecium hyaline to faintly yellowish-brown asci: prototunicate, wall thin, nonamyloid, 8-spored ascospores: simple, ellipsoid to broadly ellipsoid; 8-24 x 5-13 µm; walls: thin, hyaline Conidiomata: pycnidial, laminal, immersed conidia: ellipsoid, c. 3 x 1 µm Secondary metabolites: not detected Geography: world wide in arid to humid regions Substrate: calcareous and siliceous rocks. Notes: The filamentous nature of the cyanobiont is often hard to observe, and it seems likely that single celled cyanobacteria may also occur. Psorotichia and Lemmopsis are very similar in external appearance, but they differ in the type of ascoma ontogeny and possess more robust paraphyses.