Chaenotheca sphaerocephala Nádv.

Ann. Mycol. 40, 1/2: 134, 1942
Description: Thallus crustose, episubstratic, finely granular (granules 0.4-0.6 mm) or of verrucose granules (0.12-0.15 mm), ecorticate. Apothecia stalked, pin-like, the stalk 1.1-1.5 mm high, 0.04-0.11 mm thick, black but often covered in a thin, greyish pruina formed by a layer of ruptured surface hyphae. Capitula spherical, 0.3-0.4 mm across, with a poorly developed, up to 30 µm thick exciple which only surrounds the bare of the capitulum as a collar, sometimes missing. Mazaedium well-developed, brown, without crystalline pruina, but the lower side of the capitulum sometimes appears white-pruinose due to pale hyphae projecting from the exciple; hypothecium broadly obconical, with a strongly convex to hemispherical upper surface. Asci cylindrical, ellipsoid or irregular, formed in chains, dissolving early, with 1- or 2-seriate ascospores. Ascospores 1-celled, brown to pale brown, globose, 3-4.5 µm wide, the wall smooth or with irregular fissures. Photobiont trebouxioid, the cells < 10 µm diam. Spot tests: thallus K-, C-, KC-, P- or P+ yellowish(-orange), UV+ white. Chemistry: thallus with barbatic and obtusatic acids, rarely with squamatic acid.
Note: described from South America, this species is widespread in temperate and cool-temperate areas of the Southem Hemisphere, rare in the Northern Hemisphere, in Europe being known from a few localities scattered from Scandinavia to the montane belt of the Central Alps (Switzerland), in very shaded localitites at bases of old trunks. To be looked for in Italy.
Growth form: Crustose
Substrata: bark
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

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Predictive model

Curtis Randall Björk - CC BY-SA 4.0
Glacier National Park, Beaver Valley, British Columbia, Canada, on decaying toothed polypores on trunks of Tsuga heterophylla in antique rain forest