Placidium rufescens (Ach.) A. Massal.

Sched. Crit., 6: 114, 1856. Basionym: Endocarpon rufescens Ach. - Lichenogr. Univ.: 304, 1810.
Synonyms: Catapyrenium lachneum subsp. rufescens (Ach.) Clauzade & Cl. Roux; Catapyrenium rufescens (Ach.) Breuss; Dermatocarpon rufescens (Ach.) Th. Fr.; Dermatocarpon rufopallens (Nyl.) Zahlbr.; Dermatocarpon terrigenum Tomin; Endocarpon rufopallens Nyl.; Endopyrenium rufescens (Ach.) Körb.; Endopyrenium rufopallens (Nyl.) Müll. Arg.
Distribution: N - VG, Frl (Brackel 2013), Ven, TAA (Nascimbene & al. 2022), Lomb, Piem (Clerc & al. 1999, Isocrono & al. 2003), VA (Piervittori & Isocrono 1999), Emil (Nimis & al. 1996, Fariselli & al. 2020), Lig. C - Tosc (Brackel 2015), Umb (Genovesi & al. 2001, Ravera & al. 2006), Laz (Nimis & Tretiach 2004, Di Pietro & al. 2022), Abr (Brackel 2015), Mol (Nimis & Tretiach 1999, Caporale & al. 2008, Genovesi & Ravera 2014), Sar. S - Camp (Aprile & al. 2002, 2003b, Nimis & Tretiach 2004, Garofalo & al. 2010), Pugl, Si (Ottonello & al. 1994, Nimis & al. 1996b, Grillo 1998, Caniglia & Grillo 2001, 2005, 2006, Grillo & al. 2002, 2009, Grillo & Caniglia 2004, Merlo 2004b, Cataldo & Minissale 2013, 2015).
Description: Thallus squamulose to subfoliose, reddish brown, dull to somewhat shiny, the squamules large, to 15 mm wide, 0.3-0.6 mm thick, rounded at tips, with a mostly up-turned, undulate margin bearing black, knotty pycnidia; lower surface pale to dark brown, often blackening in central parts, attached by colourless, (5.5-)6-7.5(-8) μm thick rhizohyphae which are absent at margins. Upper cortex paraplectenchymatous, 40-80 μm thick, with an epinecral layer of variable thickness; medulla prosoplectenchymatous, of 3-5 μm thick, elongated cells; lower cortex clearly delimited from the medulla, 38-138 μm thick, of irregularly arranged, 8-23 μm wide, rounded to angular cells. Perithecia frequent, laminal, broadly pyriform, immersed in the squamules, up to 0.5 mm across, without involucrellum. Exciple pale throughout; paraphyses absent, substituted by periphyses measuring 40-60 x 3.5-5 μm. Asci 8-spored, cylindrical, thin-walled, non-amyloid and without an ocular chamber, 80-100 x 12-17(-21) μm. Ascospores 1-celled, hyaline, thin-walled, ellipsoid, uniseriately arranged in the asci, (14-)15-20(-22) x (6-)7-10(-11) μm. Pycnidia multilocular, Dermatocarpon-type, marginal, usually abundant, prominent and knob-like, black. Conidia oblong-ellipsoid to subcylindrical, 3-5 x 1.3-2.3 μm. Photobiont chlorococcoid (Myrmecia). Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a Mediterranean to (mainly) mild-temperate, holarctic lichen found on vertical seepage tracks of calcareous rocks, almost always with colonies of cyanobacteria, more rarely on plant debris, calciferous soil, terricolous or epilithic bryophytes.
Growth form: Squamulose
Substrata: rocks, soil, terricolous mosses, and plant debris
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
On otherwise dry surfaces with short periods of water seepage after rain

Commonnes-rarity: (info)

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


A. Moro; Owner: Department of Life Sciences, University of Trieste
Sicilia, TP, Segesta, presso i templi
2008.04.05



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (32334)
2001/12/08



A. Moro; Owner: Department of Life Sciences, University of Trieste
Sicilia, TP, Segesta, presso i templi
2008.04.05



A. Moro; Owner: Department of Life Sciences, University of Trieste
Sicilia, TP, Segesta, presso i templi
2008.04.05



Andrea Moro; Owner: Department of Life Sciences, University of Triedte
Italy, Friuli Venezia Giulia, Trieste, Trieste Karst, Rocca di Monrupino
20/02/2017



Andrea Moro; Owner: Department of Life Sciences, University of Triedte
Italy, Friuli Venezia Giulia, Trieste, Trieste Karst, Rocca di Monrupino
20/02/2017


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P/Placidium_rufescens.htm
France, session AFL 2010 - Hérault


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P/Placidium_rufescens.htm
France, session AFL 2010 - Hérault


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


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


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


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


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


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


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


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1123&lang=en
France, Provence, Gambois


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1123&lang=en
France, Provence, Gambois


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1123&lang=en
France, Provence, Gambois


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1123&lang=en
France, Provence, Gambois


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1123&lang=en
France, Provence, Gambois


Bernard Bouffinier - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=1123&lang=en
France, Provence, Gambois


Naira Sargsyan - Institute of Botany A. Takhtajyan, Yerevan CC BY-SA 4.0
Armenia