Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: squamulose to granulose, 1-2 (-4) µm in diam. (granules: 0.1-5 mm diam.), somewhat gelatinous, translucent when moistened squamules: up to 200 µm thick, with an irregular outline, homoiomerous, often concave when young; margins: downcurved in older thalli upper surface: blackish or brownish upper cortex: absent medulla: with predominantly anticlinally arranged hyphae; cells: 6-7 µm in diam.; cyanobacteria distributed throughout lower cortex: sometimes present in juvenile squamules at the margins; cells: 3-5 µm thick Apothecia: one to several per squamule; disc: dark red, up to 1.7 mm in diam., urceolate, flat or convex; exciple: 20-60 µm thick; hymenium: 115-150 µm tall; subhymenium: 20-35 µm thick asci: cylindrical to obovoid; walls: I+ intensely blue (with hymenial gelatin becoming secondarily brownish); 8-spored ascospores: simple, ellipsoid to fusiform, 14-18 (-26) x (4.5-) 6-10.5 µm Pycnidia: immersed conidia: fusiform, 2.5-3.5 x 1-1.5 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: usually on soil, sometimes on soil over acidic rocks, occasionally in calcareous areas World distribution: North America, Europe, southern Africa and Australasia Sonoran distribution: broadly distributed in the study area, Arizona, California, Baja California, Baja California Sur and Sonora. Notes: In general H. lutosa has a more northerly distribution (to areas well north of the Sonoran Desert) than the other species.