Thalloidima candidum (Weber) A.Massal.

Ric. Auton. Lich. Crost.: 96, 1852.. Basionym: Lichen candidus Weber - Spicil. Fl. Goett.: 193, 1778.
Synonyms: Biatorina candida (Weber) Jatta; Lecidea candida (Weber) Ach.; Psora candida (Weber) Hoffm.; Toninia candida (Weber) Th. Fr.
Distribution: N - VG, Frl, Ven (Nascimbene & Caniglia 2003c, Nascimbene 2005c, 2008c, Thor & Nascimbene 2007, Nascimbene & Marini 2007), TAA (De Benetti & Caniglia 1993, Nascimbene & al. 2006, 2022, Nascimbene 2008b), Lomb (Gheza 2019, Ravera & al. 2022), Piem (Clerc & al. 1999, Isocrono & al. 2003), VA (Piervittori & Isocrono 1999), Emil (Fariselli & al. 2020), Lig. C - Tosc (Benesperi 2006, Tretiach & al. 2008), Marc (Nimis & Tretiach 1999), Umb (Nimis & Tretiach 1999, Ravera & al. 2006), Laz, Abr (Nimis & Tretiach 1999, Caporale & al. 2016, Gheza & al. 2021), Mol (Nimis & Tretiach 1999, Caporale & al. 2008, Genovesi & Ravera 2014). S - Camp (Garofalo & al. 1999, 2010, Aprile & al. 2003, 2003b, Nimis & Tretiach 2004), Pugl (Nimis & Tretiach 1999), Bas, Cal (Puntillo 1996), Si (Nimis & al. 1996b, Grillo 1998, Grillo & Caniglia 2004).
Description: Thallus squamulose, forming regular, up to 4 cm wide rosettes. Squamules up to 5 mm in diam., more or less scattered and round when young, later adjacent to slightly imbricate, the marginal ones slightly elongated and more or less radiating, the central ones round and convex. Upper surface white, entirely covered in a farinose pruina, dull, smooth; lower surface pale brown to black. Upper cortex 30-60 µm thick, with crystals of calcium oxalate; medulla white, with crystals; lower cortex often with a grey, K+ violet pigment, usually without crystals. Apothecia frequent, lecideine, round, to 2 mm across, remaining flat and marginate, black but densely pruinose. Proper exciple dark grey in the outer rim, reddish brown within, the pigmented parts K+ and N+ violet; epithecium grey, K+, N+ violet; hymenium colourless; paraphyses simple or sparingly branched and anastomosing in upper part, thin-walled, the apical cell distinctly swollen and covered by a gelatinous pigment cap; hypothecium reddish brown. Asci 8-spored, clavate to cylindrical-clavate, the apical dome K/I+ dark blue with a pale, conical-pointed apical cushion (axial mass), the wall I-, but the thin outer gel I+ blue, Bacidia-type. Ascospores: 1-septate, hyaline, fusiform, 15-24 x 3-4 µm. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: thallus without lichen substances, Sedifolia-grey pigment in apothecia.
Note: a mainly southern, incompletely holarctic species found on steeply inclined surfaces and in fissures of calciferous rocks, chiefly limestone and dolomite, often on cyanobacteria or cyanobacterial lichens when young, with a wide altitudinal range.
Growth form: Squamulose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)
On otherwise dry surfaces with short periods of water seepage after rain

Commonnes-rarity: (info)

Alpine belt: rather rare
Subalpine belt: rather common
Oromediterranean belt: rather rare
Montane belt: rare
Submediterranean belt: rather rare
Padanian area: absent
Humid submediterranean belt: rather 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

Walter Obermayer CC BY-SA 4.0 - Source: Lichens of Noricum - http://lichens-of-noricum.uni-graz.at/


Einar Timdal - Source: http://nhm2.uio.no/lav/web/index.html - CC BY-NC



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



Felix Schumm CC BY-SA 4.0
[16614], Germany, Baden-Württemberg, Alb-Donau-Kreis, zwischen Altheim und Gerstetten an südexponierten Kalkfelsen im Hungerbrunnental, 48.59616° N, 10.03926° E, 545 m. Leg. et det. Schumm 25.08.2010



P.L. Nimis CC BY-SA 04
TSB 22510



P.L. Nimis CC BY-SA 04
TSB 35290


Walter Obermayer CC BY-SA 4.0 - Source: Lichens of Noricum - http://lichens-of-noricum.uni-graz.at/



P.L. Nimis CC BY-SA 04
TSB 37956


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_T/Textes_T2/Thalloidima_candidum.htm
France, rocher calcaire fissuré - session AFL 2005 - Lozère


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1306&lang=en
France, Provence, Drôme Remuzat