Life habit: lichenized Thallus: immersed Apothecia: not pruinose, 0.6-0.9 mm tall, 6-11 times as high as the width of the stalk stalk: in longitudinal section dark brown, consisting of densely intertwined, sclerotized hyphae; outermost part: +hyaline, with pale hyphae and a thin sheet of gelatinous material at the surface, often with brownish or olivaceous tinge, or shiny black, 0.08-0.13 mm wide capitulum: 0.21-0.28 mm in diam., lens- or slightly bell-shaped exciple: upper part of exciple often slightly translucent, pale, formed as a continuation of stalk tissue, with isodiametric to slightly elongated and anti-clinally arranged, heavily sclerotized cells; hypothecium: flat or slightly convex asci: 44 x 4-5 µm, cylindrical, with uniseriate spores ascospores: semi-mature spores without ornamentation; mature spores: ellipsoid, 11-15 x 5-7 µm, with irregular ornamentation of small pustules (minutely warted) giving rise to dotted appearance in light microscope, sometimes with a few irregular cracks Spot tests: thallus K-, C-, KC-, P-; apothecia I- Secondary metabolites: none detected. Substrate and ecology: on wood, especially conifers and oaks, also decaying stumps and logs, in fringe areas of forests in moderate to rather strong light World distribution: Europe, North, Central and South America, and Australasia Sonoran distribution: Arizona and Channel Islands, California. Notes: Calicium abietinum is recognized by its immersed thallus, the non-pruinose apothecia and the rather large spores, that have an ornamentation of minute warts.