Pycnidia: immersed to erumpent, black, subglobose, (20)30-50(-60) µm in diam.; wall: composed of dark brown cells 3-5 µm in diam. conidiogenous cells: (3.5-)4-5(-6) x (2-)3-3.5(-4) µm conidia: brown to dark brown, simple, subglobose, basally not distinctly truncate, verruculose, 23.5(-4) µm long. Hosts: Lichenoconium erodens is very common on Lecanora (mainly apothecia of L. conizaeoides) and Parmelia s. l. species, especially saprotrophic over decaying lichen tissues, also on a variety of other genera, like Cladonia, Evernia, Hypogymnia and Pertusaria; in Arizona once in the apothecia of Phacopsis over Punctelia subrudecta World distribution: Europe, North and South America Sonoran distribution: known from one locality in Arizona. Notes: Lichenoconium erodens is easily distinguished from all other members of the genus by the overall smaller dimensions of its pycnidia, conidiogenous cells and conidia. It is frequently found growing together and intermixed with Lichenoconium lecanorae, and can mostly be identified macroscopically by its pycnidial size. Lichen thalli are often first damaged or killed by another fungus (e.g., Athelia arachnoidea, Lichenoconium lecanorae), and subsequently invaded by L. erodens.