Arthothelium spectabile A. Massal.

Flot. ex A. Massal., Ric. Auton. Lich. Crost.: 54, 1852.
Distribution: N - Ven (Grube & Giralt 1996, Lazzarin 2000b), Lomb (Valcuvia & Truzzi 2007, 2007b). C - Laz, Abr, Sar (Rizzi & al. 2011, Di Nuzzo & al. 2022). S - Pugl, Si.
Description: Thallus crustose, mostly endosubstratic, effuse, greyish white to greenish grey, with or without a dark prothallus, the thalline hyphae I+ blue. Apothecia arthonioid, rounded to angular, up to 2 mm across, level with thallus, with a flat to slightly convex, black, epruinose, rough disc, without a distinct proper margin. Epithecium pale to dark reddish brown, often with bark fragments, K+ reddish; hymenium patchily brownish, up to 150 µm high, I+ red, K/I+ blue, K+ faintly green; paraphysoids branched and anastomosing, sinuous, c. 0.5-1.5 µm thick, the apices without a brown cap; hypothecium brownish, c. 50 µm high, with bark fragments, K+ faintly green. Asci 8-spored, subglobose, semi-fissitunicate, with a large apical dome and a distinct ocular chamber, lacking K/I+ blue structures. Ascospores muriform, with 5-7 transverse septa and 1-3 longitudinal septa in each transverse segment, hyaline, ellipsoid, 26-37 x 12-15 µm. Photobiont trentepohlioid. Spot tests: thallus K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a temperate-suboceanic lichen found on the smooth bark of deciduous trees in ancient forests. It is included in the Italian red list of epiphytic lichens as “Vulnerable” (Nascimbene & al. 2013c).
Growth form: Crustose
Substrata: bark
Photobiont: Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)

Commonnes-rarity: (info)

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

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model

P.L. Nimis CC BY-SA 4.0
TSB 10724

Zahlbruckner A. 1926. Lichenes (Flechten). In: Engler A. (ed.): Die natürlichen Pflanzenfamilien. 2nd ed., vol 8, W. Engelmann, Leipzig, 270 pp.

Redinger, K. (1938) Arthoniaceae, Graphidaceae . In Kryptogamen-Flora von Deutschland, Österreich und der Schweiz. Band 9, 2 Abt., Part 1 (G. L. Rabenhorst, ed.): 181–404. Leipzig: Borntraeger

P.L. Nimis CC BY-SA 4.0
TSB 10724