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Clavascidium umbrinum (Breuss) Breuss
Family: Verrucariaceae
[Catapyrenium umbrinum Breuss,  more]
Clavascidium umbrinum image
Thallus: squamulose squamules: 2-4 mm wide, 200-300 µm thick, roundish or slightly lobed, upper surface: medium to dark brown, dull upper cortex: paraplectenchymatous, 20-50 µm thick, medulla: ± filamentous with hyphae divided into a varying number of spherical cells, with a conspicuous brown basal layer of more densely aggregated spherical cells, lower cortex: no true developed lower surface: pale or blackish; rhizohyphae: brown, 4-5.5 µm in diam.; also attached with a few additional brown rhizines Perithecia: broadly pyriform, up to 0.4 mm broad, with blackish brown walls asci: clavate, c. 50-70 x 15-25 µm ascospores: biseriate, ellipsoid, 13-17 x 6-8 µm Pycnidia: laminal, immersed conidia: oblong-ellipsoid, 3-4.5 x 1.5 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on soil World distribution: scattered in Europe and North America where most records are from the periphery of the Great Plains Sonoran distribution: rarther rare in Arizona, California, Chihuahua and Baja California. Notes: Characteristic features of the species are its brown basal layer (of varying thickness) and dark perithecial walls. The thallus is rather thin and fragile.