Diplotomma pharcidium (Ach.) M. Choisy

Bull. mens. Soc. linn. Soc. Bot. Lyon, 19: 156, 1950. Basionym: Lecanora pharcidia Ach. - Syn. Meth. Lich.: 147, 1814.
Synonyms: Buellia alboatra var. athroa (Ach.) Th. Fr.; Buellia pharcidia (Ach.) Malme; Diplotomma athroum (Ach.) Kernst.; Diplotomma zaboticum Körb.; Lecanora pharcidia Ach.; Lecidea parasema var. athroa Ach.
Distribution: N - Emil (Fariselli & al. 2020).
Description: Thallus crustose, episubstratic, rather thick, areolate to verrucose-areolate, whitish to rarely pale brown, sometimes delimited by a dark prothalline line. Medulla white, not amyloid, I-. Apothecia black, lecideine, epruinose or slightly pruinose, 0.3-1(-1.5) mm across, initially immersed, then slightly prominent, with a black, flat to convex disc, a thick proper margin, and a pseudothalline margin particularly evident in young apothecia. Proper exciple brown in outer part, colourless to pale brown in inner part, of radiating hyphae; epithecium brown; hymenium colourless, K/I+ blue; paraphyses simple, c. 2 μm wide at base, slightly capitate and to 3 μm thick at apex; hypothecium brown. Asci 8-spored, clavate, with a thick apex, amyloid, with a distinct axial mass, Bacidia-type. Ascospores 3-septate, sometimes with a single longitudinal septum, brown, ellipsoid, 14-25 x 8-11 µm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C- KC-, P-. Chemistry: without lichen substances.
Note: mostly on the smooth bark of deciduous trees, much more rarely on lignum, at relatively low elevations. According to Roux & coll. (2014) this is a good species, differing from D. alboatrum in the larger apothecia with a thick margin. The Italian sample, identified by H. Sipman, was collected by V.J. Grummann near the Beach of Savio, on Platanus.
Growth form: Crustose
Substrata: bark
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

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


pH of the substrata:

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Solar irradiation:

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Eutrophication:

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Poleotolerance:

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Altitudinal distribution:

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