Pleopsidium chlorophanum (Wahlenb.) Zopf

     Thallus crustose, bordered, with convex areoles, strongly lobed at the margin by smooth and shiny lobes, yellow, bright yellow, lime yellow a little green. Apothecia generally numerous, lecanorins, 0.5-1.5 mm in diameter, at first sunk into the thallus then a little sessile, disc flat then convex, shiny, yellow-brownish, concolor rim not persistent. Simple, elliptical, colorless spores, 100 to 200 per asci, 3-4 x 1.5-2 µm according to the literature, 4-5 (6) x 1.5-2 µm according to our measurements. Photobiont: chlorococcal. No color reactions to the usual reagents. Mountain and saxicolous species occuring from the vertical faces sheltered from the rain of siliceous rocks often rich in iron. N.B. Easy to confuse with Pleopsidium flavum, the apothecia of which have a concave or plane disc and a sharp and persistent rim.