Rhizocarpon viridiatrum (Wulfen) Körb.

Syst. Lich. Germ.: 262, 1855. Basionym: Lichen viridiater Wulfen in Jacquin - Coll. Bot., 2: 186, 1788.
Synonyms: Buellia viridiatra (Wulfen) H. Olivier; Diplotomma viridiatrum (Wulfen) Jatta; Lecidea viridiatra (Wulfen) Ach.; Rhizocarpon subtile Runemark
Distribution: N - VG, Ven, TAA (Nascimbene & al. 2022), Lomb, Piem (Isocrono & al. 2004, Favero-Longo & al. 2015), VA (Piervittori & Isocrono 1999), Emil (Fariselli & al. 2020), Lig. C - Tosc (Lastrucci & al. 2009), Marc (Nimis & Tretiach 1999), Laz, Sar (Brackel & Berger 2019). S - Camp, Cal (Puntillo 1996), Si (Nimis & al. 1996b, Grillo & Caniglia 2004, Iacolino & Ottonello 2006, Brackel 2008b).
Description: Thallus crustose, greenish yellow, often growing on other crustose lichens, immersed in the host thallus or areolate, usually 0.5-2 cm across, rarely larger, usually without a distinct prothallus. Areoles round to angular, plane to strongly convex, 0.3-1.2 mm diam., smooth, epruinose. Cortex 20-40 µm thick; medulla white to yellowish in upper part, I-, K/I+ very faintly violet Apothecia lecideine, round or angular, 0.4-1 mm across, with a black, weakly to strongly convex, epruinose disc and a black, often finally excluded proper margin. Cortex cells of the proper exciple reddish brown, K+ reddish violet; epithecium brown, K+ red, granular; hymenium colourless, 85-140 µm tall; paraphysoids strongly conglutinated, richly branched and anastomosing, clavate at apex; hypothecium brown, K-. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus, lacking an ocular chamber, Rhizocarpon-type. Ascospores submuriform, dark brown to almost black, ellipsoid, (12-)15-28(-32) x 7-13(-16) µm. Photobiont chlorococcoid. Spot tests: medulla K+ yellow, C-, KC-, P-. Chemistry: rhizocarpic acid (major) and unidentified fatty acids.
Note: on basic siliceous rocks with optimum in dry-warm areas, sometimes on roofing tiles, starting the life-cycle on other crustose lichens (Aspicilia s.lat., Lecidea s.lat. and Tremolecia atrata), with a wide altitudinal range.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
paras crustose lichens

Commonnes-rarity: (info)

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

pH of the substrata:

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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

Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Mougau



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (9367)
2001/12/01


Joel Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=782&lang=en
France, Commana
with Clauzadeana macula


Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Mougau


Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Mougau


Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Mougau



P.L. Nimis CC BY-SA 04
TSB 9367


Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Mougau


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Port Manech


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Port Manech


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Corse, Bastia


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=704&lang=en
France, Port Manech