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Sarcogyne arenosa (Herre) Knudsen & Standley
Family: Acarosporaceae
[Acarospora arenosa Herre]
Sarcogyne arenosa image
Thallus: chasmolithic to epilithic and then distinct and irregularly fertile, forming a continuous crust covering a meter or more on sandstone but indistinct and areoles becoming scattered in small groups on loose or crumbling substrates; c. 1 mm wide or less areoles: (if distinct) surface: brown to gray or white, uneven, subcorticate, c. 10 µm thick medulla: prosoplectenchymatous, interlaced into the substrate algal layer: ±80 µm thick beneath apothecia and forming a variable stratum in the thallus and extending into the substrate; cells: up to 12 µm wide Apothecia: one per areole, abundant, erupting from areole, raised above the thallus, round, 0.4-1.2 mm across disc: black (reddish black when wet), uniform (in one specimen compressed), plane to convex, rough, epruinose to lightly pruinose (small scattered crystals) margin: black to light brown, almost excluded in some specimens amphithecium: absent though shreds of thallus may cling as a veil or ring (sometimes white) to emergent apothecia with a proper exciple or appearing as thalline margin true exciple: (20-)40-60 µm thick, with radiating hyphae, externally black to dark brown, internally orange-red to brown to hyaline, often in gradations towards hymenium epihymenium: dark reddish brown to yellow, 10-30 µm thick, conglutinate hymenium: yellow-brown to orange, ±hyaline in thin section, 70-100 µm tall; paraphyses: septated, upper segments sometimes becoming constricted at septa, conglutinated, basally c. 2 µm wide, apically expanded up to 4 µm wide subhymenium: hyaline, 10-40 µm thick hypothecium: hyaline or black, 10-100µm thick asci: clavate, 70-80 x 15-17 µm, 100+-spored ascospores: hyaline, simple, ellipsoid, 3.5-4.9 x 1-1.5 µm Pycnidia: not observed Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on sandstone, granite, carbonaceous rock, and decomposing granite mixed with soil World distribution: western North America (throughout California) Sonoran distribution: southern California. Note: Sarcogyne arenosa is uncommon but widespread in California. It appears to be closely related to S. regularis