Rhizocarpon ridescens (Nyl.) Zahlbr.

in Engler & Prantl, Natürl. Pflanzenfam., 1 ed.: 138, 1905. Basionym: Lecidea ridescens Nyl. - Flora, 64: 533, 1881.
Synonyms:
Distribution: N - Frl (Tretiach & Hafellner 2000), TAA (Lecid. Exs. 278: Hertel 1992b), Lomb (Dalle Vedove & al. 2004, Nascimbene 2006), Piem (TSB 33849). C - Tosc (TSB 15517).
Description: Thallus crustose, episubstratic, areolate, bright yellow to yellow-green, forming patches 2-10 cm in diam. Areoles 0.1-1 mm wide, 0.3-0.5 mm thick, strongly convex, dispersed on a black hypothallus, round, smooth, matt, with a 0.2-0.5 mm wide, maculiform, central soralium; individual soredia c. 50 µm wide. Cortex poorly differentiated, c. 40 µm thick; medulla white, I+ blue. Apothecia rare, lecideine, black, 0.5-1 mm across, more or less round, with a flat disc and a usually persistent proper margin. Proper exciple brownish red in outer part, K+ intensifying red; epithecium reddish brown, K+ reddish violet; hymenium colourless, 90-120 µm high; apical cells of paraphysoids clavate, transparent; hypothecium brown, 100-300 µm high, K-. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus, lacking an ocular chamber, Rhizocarpon-type. Ascospores submuriform, brown, ellipsoid, 20-30 x 12-16 µm. Photobiont chlorococcoid. Spot tests: medulla K-, C-, KC-, P+ yellow. Chemistry: cortex with rhizocarpic acid, medulla with psoromic acid.
Note: on iron-rich siliceous rocks, mostly under overhangs, near or above treeline; easily overlooked, being always sterile.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)
In underhangs rarely wetted by rain
Species of metal-rich rocks

Commonnes-rarity: (info)

Alpine belt: very rare
Subalpine belt: very rare
Oromediterranean belt: absent
Montane belt: absent
Submediterranean belt: absent
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: absent
Dry mediterranean belt: absent

pH of the substrata:

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(info)

Solar irradiation:

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Aridity:

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Eutrophication:

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Poleotolerance:

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Altitudinal distribution:

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Predictive model
Herbarium samples
Index Fungorum GBIF


P.L. Nimis CC BY-SA 04
TSB 41151



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (12311)
2003/03/17



Juri Nascimbene - CC BY-SA 4.0
Stelvio National Park, Reg. Trentino-Alto Adige Prov. Trento, Italy.
07.2005



Pier Luigi Nimis CC BY-SA 4.0
TSB 41148



Pier Luigi Nimis CC BY-SA 4.0
TSB 41148



Pier Luigi Nimis CC BY-SA 4.0
TSB 41150



Juri Nascimbene - CC BY-SA 4.0
Mt. Adamello (Alps), Italy
2006



Pier Luigi Nimis CC BY-SA 4.0
TSB 41151