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 or squamulose, upper surface: dull gray-purplish or copper red, smooth upper cortex: paraplectenchymatous medulla: indistinctly separated from ±diffuse photobiont layer photobionts: primary one a chlorococcoid green alga, secondary photobiont absent lower cortex: absent Ascomata: absent or present, apothecial, laminal on thallus, orbicular or lingulate, immersed to semi-immersed, margin indistinct, with thalloid rim ascomata ontogeny: hemiangiocarpous, forming pycnoascocarps from ascogonia beneath pycnidia exciple: hyaline, epithecium: pale red or pale brown hymenium: hyaline, paraphyses: robust, distinctly septate, moniliform, sparingly branched and anastomosing; apical cells: c. 5 µm wide, reddish pigmented; hypothecium: hyaline asci: lecanoralean, rostrate, wall thick, inner wall layers with a amyloid collar, 8-spored ascospores: hyaline, simple, falcate to allantoid; 7-17 µm long, 2-7.5 µm wide, with a thin wall Conidiomata: pycnidial, laminal, immersed conidia: globose or ellipsoid, c. 3 x 1 µm Secondary metabolites: none detected Geography: Northern Hemisphere in arid, semi-arid and warm temperate regions Substrate: siliceous rock. Notes: Recent molecular studies (Schultz and Büdel, unpublished) revealed that Harpidium rutilans and Euopsis pulvinata do not belong to the Lichinaceae but form a separate clade. As a consequence, it is proposed to re-establish the family Harpidiaceae.