Arthonia clemens (Tul.) Th. Fr.

K. Svenska Vetensk.-Akad. Handl., n. ser. 7, 2: 46, 1867. Basionym: Phacopsis clemens Tul. - Ann. Sc. Nat. Bot., ser. 3, 17: 124, 1852.
Synonyms: Arthonia vagans var. lecanorina Almq.; Coniangium clemens (Tul.) Stein; Conida clemens (Tul.) A. Massal.
Distribution: N - Ven, TAA (Hafellner 1995b, Nascimbene & al. 2004), Lomb (Fleischhacker & al. 2016 ), Piem (Isocrono & al. 2004).
Description: Thallus inapparent, not lichenized, the hyphae developing inside the apothecial discs of Rhizoplaca-species. Apothecia arthonioid, immersed in those of the host, more or less round, to 2 mm across, with a black, often marginally paler, slightly convex disc, without a distinct proper margin. Exciple poorly developed, not evident; epithecium olive-brown, 15-20 µm high; hymenium colourless, 25-35 µm high, I+ red, K/I+ blue; paraphysoids branched, the apical cells enlarged, to 3 µm wide; hypothecium colourless, c. 20 µm high. Asci 8-spored, broadly clavate to subglobose, semi-fissitunicate, with a large, non-amyloid apical dome, and a distinct ocular chamber, Arthonia-type. Ascospores 1-septate, hyaline, obovate, one cell larger and longer, 10-14 x 4-7 µm, without an epispore. Photobiont absent. Spot tests: K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a holarctic lichenicolous fungus growing in the apothecia of Rhizoplaca chrysoleuca, very much confused with other species in Italy (see note on A. galactinaria). Records from other hosts than Rhizoplaca are not reported here.
Growth form: Lichenicolous fungus
Substrata: rocks
Reproductive strategy: mainly sexual
paras Rhizoplaca

Commonnes-rarity: (info)

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

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model
Herbarium samples

Serge Poumarat - Source:
France, session AFL Pyrénées-Orientales - 2012