ITALIC 8.0

Rhizocarpon drepanodes Feuerer

Ber. bayer. bot. Ges., 49: 67, 1978.

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Description: Thallus crustose, episubstratic, bright yellow-green, dull, areolate, forming 0.5-3(-5) cm wide patches, usually delimited by a black prothallus, the areoles 0.5-1.2(-1.5) mm wide, strongly convex, widely scattered over a black hypothallus, mostly crescent-shaped around the apothecia, smooth. Cortex poorly differentiated, c. 40 µm thick; medulla white, I+ blue. Apothecia lecideine, black, 0.4-0.8 mm across, round to weakly angular, with a concave to flat disc and a rather thick, persistent proper margin. Proper exciple brownish, K+ purple-red; epithecium greenish brown, K- or K+ intensifying green; hymenium colourless to greenish in upper part, 140-160 µm high; paraphysoids coherent, branched and anastomosing, the apical cells clavate; hypothecium brownish, K-. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus that is K/I- in lower part and K/I+ blue near the apex, lacking an ocular chamber, Rhizocarpon-type. Ascospores muriform, with (26-)30-34(-48) cells visible in optical view, dark brown, ellipsoid 28-54 x 15-25 µm, halonate when young. Photobiont chlorococcoid. Spot tests: medulla K-, C-, KC-, P+ yellow-orange. Chemistry: cortex with rhizocarpic acid, medulla with psoromic acid.

Note: similar to Rh. ferax in the thallus with scattered, convex, roundish to lunulate areoles with laterally attached apothecia, but ascospores larger and with a higher number of cells in optical view; on steep rock faces and under overhangs of siliceous rocks, in upland areas. Widespread in Europe, including the Alps. According to Roux & Coll. (2025), however, all of the records from the French Alps are either very dubious or refer to specimens of R. lecanorinum with a medulla reacting P+ yellow. To be looked for in the Italian Alps.

Growth form: Crustose

Substrata: rocks

Photobiont: green algae other than Trentepohlia

Reproductive strategy: mainly sexual

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Altitudinal distribution:

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Predictive model

Detail from: https://gzu.jacq.org/GZU000286030

GZU000286030 - T. Feuerer Date 1977-08-14 Location France Label Flora von Frankreich - Dep. Haute Garonne, Pyrenäen, Südende des Vallee du Lis S Bagneres de Luchon, am Aufstieg zur Pic Sarnes ; Alt. 1500 m Habitat kleine Steilwand am Weg, E-Exposition, schattig