Placopyrenium fuscellum (Turner) Gueidan & Cl. Roux

in Navarro-Rosinés & al., Bull. Soc. Linn. Prov., 58: 174, 2007. Basionym: Lichen fuscellus Turner - Trans. Linn. Soc. London, 7: 90, 1804.
Synonyms: Lithocia fuscella (Turner) A. Massal.; Verrucaria fuscella (Turner) Winch; Verrucaria fuscella var. crassa Garov.; Verrucaria fuscella var. subviridula Garov.; Verrucaria glaucelloides Hepp; Verrucaria glaucina sensu Zetterst. et auct. p.p non Ach.; Verrucaria glaucina var. caeruleoalba B. de Lesd.; Verrucaria glaucina var. furva Hue; Verrucaria glaucina var. griseoatra (Kremp.) J. Steiner; Verrucaria glebulosa Nyl.; Verrucaria griseoatra (Kremp.) Servít; Verrucula fuscella (Turner) J. Steiner
Distribution: N - VG, Frl (TSB 2206), Ven (Breuss 2009), TAA, Lomb, Piem (Isocrono & al. 2004), VA (Piervittori & Isocrono 1999), Emil (Breuss 2009, Fariselli & al. 2020), Lig (Giordani & al. 2016). C - Tosc (Breuss 2009), Paoli & al. 2014b), Marc (Nimis & Tretiach 1999), Umb (Ravera & al. 2004, 2006b, Genovesi 2011), Laz (Pietrini & al. 2008, Genovesi & al. 2011), Abr (Nimis & Tretiach 1999, Gheza & al. 2021), Mol (Garofalo & al. 1999, Nimis & Tretiach 1999), Sar (Rizzi & al. 2011, Giordani & al. 2013). S - Camp (Garofalo & al. 1999, Aprile & al. 2003b, Nimis & Tretiach 2004), Pugl (Garofalo & al. 1999, Nimis & Tretiach 1999), Cal, Si (Grillo 1998, Grillo & Caniglia 2004, Caniglia & Grillo 2005, 2006).
Description: Thallus crustose, episubstratic, well developed, areolate, 0.25-0.8 mm thick, often forming small, up to c.1 cm wide patches, but individual thalli often coalescing to cover larger surfaces, the areoles angular to elongated at margins, 0.3-1.4 x 0.7-1.8 mm, often divided into smaller units by dark lines, the thallus becoming cracked into 0.6-2 mm wide, mature areoles; upper surface pale grey, usually pruinose, the margins and the sides dark brown to black. Cortex poorly defined, paraplectenchymatous, the cell walls with a brown pigment, overlain by an up to 6 μm thick epinecral layer; medulla densely pigmented. Perithecia black, laminal, 1-10(-30) per areole, immersed, the apex 0.06-0.1 mm diam., flat to slightly convex. Involucrellum absent; exciple colourless to pale brown in lower part, brown in upper part, the pigmented parts K+ darker brown or greenish brown; hamathecium of periphyses and periphysoids, interascal filaments absent; hymenial gel hemiamyloid, I+ red (I+ blue at very low concentrations of I), K/I+ blue. Asci 8-spored, clavate, I-, fissitunicate, the wall thickened above with an indistinct ocular chamber, Verrucaria-type. Ascospores 1-celled, hyaline, oblong-ellipsoid, (11.5-)13-17(-20.5) x 4.5-6(-7.5) μm. Pycnidia very rare, laminal, multilocular, Dermatocarpon-type. Conidia simple, hyaline, bacilliform, c. 4.5 x 1.2 μm. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on steeply inclined calciferous rocks (mainly limestone and dolomite), often on Verrucaria nigrescens; a polymorphic taxon in need of revision. For further details see Nimis (1993: 739) and Orange (2013b).
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
paras on Bagliettoa and Verrucaria when young
Poorly known taxon in need of further study

Commonnes-rarity: (info)

Alpine belt: rare
Subalpine belt: rather common
Oromediterranean belt: rather rare
Montane belt: common
Submediterranean belt: very common
Padanian area: very rare
Humid submediterranean belt: very common
Humid mediterranean belt: rather common
Dry mediterranean belt: rather 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 (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placopyrenium_fuscellum.htm
France, session AFL 2015 dans le Lot


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placopyrenium_fuscellum.htm
France, session AFL 2015 dans le Lot


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_3/Placopyrenium_fuscellum.htm
France, session AFL 2015 dans le Lot


Zschacke, H. (1934) Epigloeaceae, Verrucariaceae und Dermatocarpaceae. In: Dr. L. Rabenhorst‘s Kryptogamen-Flora, Band 9, Abt. 1, Teil 1. Akademische Verlagsgesellschaft, Leipzig, 695 pp. - Public Domain


G. Gibelli, in S. Garovaglio, 1865 Tentamen Dispositionis Methodicae Lichenum In Longobardia Nascentium. Mediolanum
as Verrucaria glaucina


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


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=lichens&lettre=P&lang=en
France, Sainte Anne la Palud


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=lichens&lettre=P&lang=en
France, Sainte Anne la Palud


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=lichens&lettre=P&lang=en
France, L'Aber


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=lichens&lettre=P&lang=en
France, L'Aber


Michel David - Source: http://www.lichensmaritimes.org/index.php?task=lichens&lettre=P&lang=en
France, Croozn, L'Aber


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


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


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=lichens&lettre=P&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; Buffavento Castle (and surroundings)


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; Buffavento Castle (and surroundings)


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; Buffavento Castle (and surroundings)