Arthonia excentrica Th. Fr.

K. Svenska Vetensk.-Akad. Handl., 7, 2: 46, 1867.
Synonyms: Allarthonia excentrica (Th. Fr.) Zahlbr.; Arthonia albinula Nyl.
Distribution: N - Emil (Tretiach & al. 2008, Brackel 2016, Fariselli & al. 2020).
Description: Thallus inapparent, not lichenized, developing on the thalli of leprose lichens. Apothecia arthonioid, immarginate, dark purplish brown when dry, rounded, flat to finally convex, 0.1-0.3 mm across, at first partially immersed in the host thallus. Proper exciple poorly developed; epithecium dark reddish brown; hymenium colourless to pale yellowish brown, 50-60 µm high; paraphysoids branched and anastomosing, the apical cells brown-capped, c. 3 µm wide; hypothecium brownish, K+ olive-brown. Asci 8-spored, broadly clavate, semi-fissitunicate, with a large apical dome, a distinct ocular chamber, and a K/I + blue part near the apex of the ocular chamber, Arthonia-type. Ascospores (1-)3-septate (both 1- and 3-septate spores sometimes occurring together in the same ascus), hyaline, 12-15(-17) x (3-)3-5(-6.5) µm. Photobiont absent. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a non-lichenised lichenicolous fungus growing on Lepraria-species; probably more widespread, but largely overlooked.
Growth form: Lichenicolous fungus
Reproductive strategy: mainly sexual
paras Lepraria spp.

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: absent
Dry mediterranean belt: absent


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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