Circinaria gibbosa (Ach.) A. Nordin, Savić & Tibell

Mycologia, 102: 1346, 2010. Basionym: Urceolaria gibbosa Ach. - Meth. Lich.: 144, 1803.
Synonyms: Aspicilia gibbosa (Ach.) Körb.; Circinaria gibbosa (Ach.) A. Nordin, Savic & Tibell; Lecanora gibbosa (Ach.) Nyl.
Distribution: N - TAA, Lomb, Piem.
Description: Thallus crustose, episubstratic, verrucose-areolate, yellowish grey to bluish-grey, sometimes delimited by a dark prothallus. Areoles 0.6-1 mm wide, usually rounded, convex, developing on a dark hypothallus; medulla white, filled with crystals, opaque, I-. Apothecia lecanorine-aspicilioid, 0.3-0.6 mm across, immersed, usually 1 per areole, with a black, epruinose, flat disc, and a very thin, persistent, often split thalline margin. Excipulum poorly developed, to 25 µm wide; epithecium olive green to olive-brown, N+ green, K+ brown; hymenium colourless, 120-150(-185) µm high, I+ blue or sometimes partly turning yellow-green; paraphyses in lower part 1.7-2.5 µm thick, in upper part slightly branched and anastomosing, submoniliform, to 3.5 µm wide at tips; hypothecium colourless, I+ blue. Asci (6-)8-spored, cylindrical-clavate, the thin outer coat K/I+ blue, the wall and apical dome K/I-. Ascospores 1-celled, hyaline, broadly ellipsoid to subglobose, 20-26 x 12-14(-18) µm. Pycnidia partially immersed, with a black, punctiform ostiole. Conidia filiform, 6-8 x c. 1 µm. Photobiont chlorococcoid. Spot tests: cortex K-, C-, KC-, P-; medulla K+ yellow turning red (crystals), but only after pretreatment with HCl. Chemistry: aspicilin, medulla with norstictic acid in low concentrations.
Note: on siliceous rocks wetted by rain in the mountains. The epithet gibbosa was frequently used by European authors for C. caesiocinerea, so that the presence of this northern species in the Alps is dubious.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

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


pH of the substrata:

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Eutrophication:

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Poleotolerance:

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Altitudinal distribution:

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Author: Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php