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, emarginate, black, rounded, flat to finally convex, usually veru small, 0.1-0.35 mm across, at first partially immersed in the host thallus. Proper exciple poorly developed; epithecium pale brown, of subhorizontally arranged parpahysoids; hymenium colourless to brownish with a greenish hue, 35-50 µm high, I+ red, K/I+ blue; paraphysoids branched and anastomosing, the apical cells brown-capped with intracellular pigment, 3-4 µm wide; hypothecium brown, 7-10 μm high. Asci 8-spored, broadly obpyriform, 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, 32-43 x 18-21 μm. Ascospores 1-septate, not constricted at septum, with unequal cells, hyaline, ellipsoid to oblong, 11-15(-17) x (3-)4-5(-5.5) µm, the wall I+ red. 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
Substrata: rocks, bark, and lignum
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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Predictive model
Index Fungorum GBIF

United States National Herbarium - Smithsonian (US:Lichens) - Collector: R. Santesson & R. Moberg Number: P2821 Date: 1981-02-17 Locality: Peru, Pasco, Pasco, ca. 3 km SE of Cerro de Pasco. -10.7 -76.25 - CC BY-NC 3.0 - Source: Consortium of Lichen Herbaria (2023) http//:lichenportal.org/portal/index.php. Accessed on December 15.