Chrysothrix caesia (Flot.) Ertz & Tehler
Fungal Divers., 49: 53, 2011. Basionym: Coniangium caesium Flot. in Körb. - Syst. Lich. Germ.: 295, 1855.
Synonyms: Allarthonia caesia (Flot.) Zahlbr.; Arthonia caesia (Flot.) Körb.
Distribution: N - Frl.
Description: Thallus crustose-subleprose, thinly episubstratic, yellowish green to greyish-green, sometimes with a bluish hue, entrely powdery-granulose, poorly delimited, usually without a distinct prothallus, covered with very thin, acicular crystals in herbarium specimens. Apothecia rather rare, without a proper margin, more or less round, 0.2-0.4(-0.7) mm across, at first immersed in the thallus, with a dark brown to black, but densely bluish-grey pruinose, flat to slightly convex disc. Proper exciple poorly developed, very thin, reddish brown; epithecium reddish brown c. 10 μm high; hymenium colourless to yellowish brown, 60-75 μm high; paraphysoids rather thin, sparingly branched and anastomosing, not or only slightly thickened at apex; hypothecium dark red-brown, conical, up to 60 μm high. Asci 8-spored, broadly clavate to subglobose. Ascospores 3-septate, slightly constricte in the middle, more or less bacilliform, 15-22(-24) x 4-6 μm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ pale yellow, C-, KC- or KC+ pale yellow, P-, UV-. Chemistry: usnic acid in thallus, perhaps also zeorin.Note: a mild-temperate species also known from North America, found on the smooth bark of deciduous trees, especially Carpinus; often sterile and overlooked, being easily confused with species of Lepraria.
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: extremely rare
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: absent
Dry mediterranean belt: absent

Predictive model
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: extremely rare
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: absent
Dry mediterranean belt: absent

Predictive model