Diorygma archeri

Diorygma archeri has a flat thallus that is usually white or grayish-green in color and up to 800 μm thick. The outer layer of the lichen (the pseudocortex) is distinct, reaching up to 30 μm. The algal layer is well-developed and about 50–60 μm thick. The inner layer, the medulla, is white and thick, with crystals scattered throughout it.^[2]

The fruiting bodies of the lichen, called ascomata, are numerous and can vary in shape, with some being short and curved while others are more branched. They are covered by a brownish or reddish-brown layer that is surrounded by a raised, irregular margin. The hymenium, which is the part of the ascomata that contains the spores, is hyaline and can be seen to be violet-blue when treated with certain chemicals. The spores themselves are oval to elliptic in shape, multicellular, and range in size from 150 to 255 x 53 to 85 μm.^[2]

Diorygma archeri contains protocetraric acid, a lichen product that can be detected using thin-layer chromatography.^[2]

Diorygma archeri is comparable to Diorygma pruinosum, but the two differ in several ways. Specifically, D. archeri has a thick, distinctly corticate body that is grayish-green in color and contains a well-developed medulla. The apothecial disc of D. archeri is only slightly open, and its proper exciple is not carbonized. Additionally, Diorygma archeri has larger ascospores than D. pruinosum.^[2]