Placopyrenium trachyticum (Hazsl.) Breuss

in Nimis & Poelt, Studia Geobot., 7, suppl. 1: 183, 1987. Basionym: Endopyrenium trachyticum Hazsl. - Verh. Ver. f. Naturk., Pressburg, 5: 7, 1861.
Synonyms: Catapyrenium trachyticum (Hazsl.) R. Sant.; Dermatocarpon trachyticum (Hazsl.) Vain.; Placidiopsis trachytica (Hazsl.) Servít; Verrucula subcrustosa (Nyl.) J. Steiner
Distribution: N - Ven (Breuss 2009). Piem, VA (Piervittori & Isocrono 1999), Lig. C - Tosc, Sar. S - Camp, Pugl, Si (Nimis & al. 1996b).
Description: Thallus subcrustose-subsquamulose, areolate, the areoles (1-)2-5(-8) mm wide at maturity, more or less polygonal in shape to irregular and finely incised, the peripheral ones often somehow elongated, separated by wide cracks showing the black side-walls, the upper surface pale grey-brown, but usually whitish grey-pruinose, subdivided by dark lines in few to numerous (up to 30) small units; areoles attached by elongate, more or less twisted and irregularly swollen stipes which have a carbonaceous cortex and a pale interior. Upper cortex paraplectenchymatous, overlain by a thick epinecral later; medulla white, I-, without a black basal layer. Perithecia black, 0.2-0.3 mm across (in section), completely immersed in the squamules, 1-5(-10) per squamule, without an involucrellum. Exciple pale throughout, except around the dark ostiolar region; 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, broadly ellipsoid, (11.5-)13-20 x 5-7.5 µm. Photobiont chlorococcoid. Spot tests: Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on base-rich siliceous rocks. This species, frequently confused with P. fuscellum, extends more widely in the submediterranean belt than P. bucekii.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: extremely rare
Submediterranean belt: very rare
Padanian area: absent
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

Harrie Sipman – Source http://www.bgbm.fu-berlin.de/sipman/Zschackia/AegeanLichens/CaloplacaAC.htm - As Caloplaca oasis


Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P/Placopyrenium_trachyticum.htm
France, novembre 2015 - St Prejet Armandon - Haute-Loire


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne


Jacques Haine - Source: http://www.lichensmaritimes.org/index.php?task=fiche&lichen=835&lang=en
France, Argonne