Slideshow image
Lecanora thallophila H. Magn.
Family: Lecanoraceae
Lecanora thallophila image
Bruce Ryan  
Life habitat: lichenicolous Thallus: within substrate, not visible Apothecia: occurring singly, constricted at base, concave, cup-like when young and flat when mature, 0.5-2.7 mm in diam. disc: shades of yellow or pale greenish yellow, smooth, slightly pruinose margin: paler than the disc, prominent or even with disc, smooth, uniform, not or slightly flexuose, epruinose, without a parathecial ring amphithecium: present, with widely scattered algae in the medulla but reaching top of margin and forming a continuous algal layer (120-170 µm thick) below hypothecium, with medullary tissues composed of loose, thick hyphae filled by coarse, brown granules (pol+, insoluble in K, soluble in N -allophana-type?), corticate; cortex: distinctly delimited, slightly thicker at the base than at the sides, 45-50 µm wide laterally and 50-70 µm wide at base, transparent (cortical granules absent), cellular (composed of pseudoparenchyma), not gelatinous parathecium: hyaline, c. 25 µm thick, with periclinal hyphae c. 4 µm wide and lumina c. 1 µm wide epihymenium: hyaline, granular (pol+), granules coarse, superficial, soluble in K and N (chlarotera-type?) hymenium: hyaline, c. 60 µm tall; paraphyses: highly branched and anastomosing, thick, not expanded or pigmented, coherent in K; subhymenium: hyaline, indistinct; hypothecium: hyaline, clear, composed of prosoplectenchyma, without granules, 30-45 µm thick asci: clavate, 4-8-spored ascospores: hyaline, simple, ellipsoid, 8.9-11.8 x 4.5-5.9 µm Pycnidia: not seen Spot tests: apothecial margin K+ persistently yellow, C-, KC+ gold, P-; disc K+ yellow, C+ yellow, KC+ yellow to orange, P-; apothecia UV negative Secondary metabolites: unknown (Rf 6-7, brown spot - Rf like atranorin, but color similar to usnic acid). Substrate and ecology: parasitic on thallus of Dermatocarpon americanum World distribution: western North America Sonoran distribution: known from two localities in Grand Canyon National Park, Arizona. Notes: This lichenicolous species is characterized by distinctly yellow and quite large apothecia (up to 2.7 mm in diam.). Although the species was considered by the author (H. Magnusson) as belonging to L. dispersa group, it does not seem to be related with that group due to the presence of isousnic acid and location of amphithecial granules mostly in algal-containing part of amphithecium.