Rhizocarpon ferax H. Magn.

Bot. Not., 101: 405, 1948.
Synonyms:
Distribution: N - TAA (Nascimbene 2005).
Description: Thallus crustose, episubstratic, yellow-green, to yellow-grey, areolate, usually delimited by a black prothallus, forming small patches 0.5-1 cm in diam, rarely up to 3 cm. Areoles 0.5-1 mm wide, usually scattered over a black hypothallus, rarely forming a continuous crust, mostly crescent-shaped around the apothecia, convex, smooth, dull. Cortex poorly differentiated, c. 40 µm thick; medulla white, I+ blue. Apothecia lecideine, black, 0.4-0.7 mm across, round to weakly angular, with a concave to flat disc, and a rather thick, persistent proper margin. Proper exciple brownish, K+ brownish red; epithecium greenish brown to green, K- or K+ intensifying green; hymenium colourless to greenish in upper part, 130-200 µm high; apical cells of paraphysoids clavate, transparent; hypothecium brownish, K-, 50-200 µm high. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus, lacking an ocular chamber, Rhizocarpon-type. Ascospores muriform, dark brown, ellipsoid 25-40(-54) x 14-18(-25) µm. Photobiont chlorococcoid. Spot tests: medulla K-, C-, KC-, P+ yellow. Chemistry: cortex with rhizocarpic acid, medulla with psoromic acid.
Note: on siliceous rocks near and above treeline, starting the life-cycle on other crustose lichens; probably more widespread in the Alps.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
paras crustose lichens

Commonnes-rarity: (info)

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

pH of the substrata:

12345

Solar irradiation:

12345

Aridity:

12345

Eutrophication:

12345

Poleotolerance:

0123

Altitudinal distribution:

123456


Predictive model
Herbarium samples

Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)