Rhizocarpon petraeum (Wulfen) A. Massal.

Ric. Auton. Lich. Crost.: 102, 1852. Basionym: Lichen petraeus Wulfen - Schr. Ges. naturf. Fr. Berlin, 8: 89, 1787.
Synonyms: Buellia concentrica auct.; Lecidea carphina Ach.; Lecidea excentrica (Ach.) Röhl.; Lecidea petraea (Wulfen) Ach.; Rhizocarpon concentricum auct. non (Davies) Beltr.; Rhizocarpon excentricum (Ach.) Arnold; Rhizocarpon perlutum auct. non (Nyl.) Zahlbr.; Rhizocarpon petraeum f. albicans (Körb.) Jatta; Rhizocarpon petraeum f. dealbatum A. Massal.; Rhizocarpon petraeum f. lapicida A. Massal.; Rhizocarpon petraeum f. orbiculare A. Massal.; Rhizocarpon petraeum var. subconcentricum Körb.; Rhizocarpon subconcentricum (Körb.) Körb.; Rhizocarpon variegatum J. Steiner
Distribution: N - VG, Frl, Ven (Caniglia & al. 1999, Lazzarin 2000b), TAA (Nascimbene 2001b, 2003, 2005b, 2006c, Nascimbene & al. 2022), Lomb, Piem (Isocrono & al. 2004, Favero-Longo & al. 2004, 2006b), VA (Piervittori & Isocrono 1999, Isocrono & al. 2008, Favero-Longo & Piervittori 2009), Emil (Dalle Vedove & al. 2002, Fariselli & al. 2020), Lig. C - Tosc, Marc, Umb (Ravera & al. 2006), Laz, Abr (Nimis & Tretiach 1999), Sar (Rizzi & al. 2011, Giordani & al. 2013). S - Camp (Ricciardi & al. 2000, Aprile & al. 2003, 2003b, Nimis & Tretiach 2004), Pugl (Nimis & Tretiach 1999), Bas, Cal (Puntillo 1996), Si.
Description: Thallus crustose, cracked to slightly areolate towards the center, white to pale grey, sometimes delimited by a thin dark prothallus, forming orbicular patches to 5 cm diam. Areoles angular, flat to slightly convex, c. 0.5 mm wide. Apothecia lecideine, black, up to 1 mm across, often arranged in concentric circles, innate, angular to oval, with a first flat, then convex, rough, not pruinose disc and a persistent proper margin which is paler in colour and often tinged with blue or green, sometimes white-pruinose. Proper exciple dark blue-green in outer part, colourless to pale brown in inner part, K+ yellow, containing crystals; epithecium olive-brown, with crystals dissolving in K, K+ yellow; hymenium colourless, to 200 µm tall; paraphysoids slender, scarcely swelling at apex, without a strongly delimited pigmented cap; hypothecium dark brown, K-. Asci 8-spored slightly clavate, Rhizocarpon-type. Ascospores muriform, hyaline, sometimes pigmented when very old, 20-50 x 13-25 µm. Photobiont chlorococcoid. Spot tests: medulla K+ yellow, C-, KC-, P+ orange. Chemistry: stictic acid.
Note: a widespread, holarctic pioneer species of base-rich siliceous rocks, often found on roofing tiles and on slightly calciferous sandstone, with a wide altitudinal range.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Pioneer species

Commonnes-rarity: (info)

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

Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (29124)
2001/12/10



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (29124)
2001/12/10


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_R/Rhizocarpon_petraeum.htm
France


Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Joël Querellou - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Lostmarc'h


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Lostmarc'h


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Lostmarc'h


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Miche David - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Port Croix


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Pont Croix


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Pont Croix


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Pont Croix


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Pont Croix


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Pointe de Kerdra


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, Pointe de Dinan


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=169&lang=en
France, L'Aber


Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
SE-Europe; N-Cyprus; SE of Girne; Beşparmak Mountains; between Girne Kayasi and Armenian Monastery (Sourp Margar)


Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
SE-Europe; N-Cyprus; SE of Girne; Beşparmak Mountains; between Girne Kayasi and Armenian Monastery (Sourp Margar)


Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
SE-Europe; N-Cyprus; SE of Girne; Beşparmak Mountains; between Girne Kayasi and Armenian Monastery (Sourp Margar)


Ulrich Kirschbaum
Central Europe; Germany: Hesse. (Coll/ident: Eichler/Cezanne).