Rhizocarpon atroflavescens Lynge

Lich. Novaya Zemlya: 141, 1928.
Synonyms: Rhizocarpon atroflavescens subsp. pulverulentum (Schaer.) Runemark; Rhizocarpon chiastomerum Lettau; Rhizocarpon geographicum var. contiguum f. calcicolum Anzi; Rhizocarpon pulverulentum (Schaer.) Räsänen
Description: Thallus crustose, episubstratic, rimose-areolate, yellowish white to white, finely pruinose, forming 2-5 cm patches delimited by a bluish grey, but white-pruinose prothallus, the areoles contiguous, forming a more or less continuous crust, 0.3-1.5 mm wide, irregularly subdivided by numerous cracks, more or less flat. Cortex without a distinct structure, 40-75 µm thick; medulla white, I+ deep blue. Apothecia frequent, lecideine, but sometimes appearing almost lecanorine, being often surrounded by the areoles, arising between the areoles, rounded, 0.3-1(-1.5) mm across, with a black, slightly concave to flat, epruinose disc and a very thin, sometimes finally excluded proper margin. Proper exciple brownish red, K+ purple-red; epithecium reddish brown, K+ purple-red; hymenium colourless, 90-150 µm high; paraphysoids strongly coherent, richly branched and anastomosing, the apical cells clavate; hypothecium brown, 100-300 µm high, K-. Asci 8-spored, clavate, fissitunicate, with a well-developed tholus that is K/I- in lower part and K/I+ blue near the apex, lacking an ocular chamber, Rhizocarpon-type. Ascospores (1-)3(-4)-septate, rarely submuriform and with a 1(-2) transverse septa (with 4-10 cells in optical view), soon becoming dark green to brown, ellipsoid, (18-)23-32(-38) x (9-)12-16(-20) µm, halonate. Photobiont chlorococcoid. Spot tests: medulla K-, C-, KC-, P- or P+ yellow. Chemistry: cortex with rhizocarpic acid; medulla with variaqble amounts of psoromic acid.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
paras Pertusaria

Commonnes-rarity: (info)

Alpine belt: rather common
Subalpine belt: rather rare
Montane belt: absent
Dry submediterranean belt: absent
Humid submediterranean belt: absent
Padanian area: absent

pH of the substrata:

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Altitudinal distribution:

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Rarity

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Predictive map

P.L. Nimis CC BY-SA 04
TSB 25197


P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (25197)
2001/11/30


Source: https://nhm2.uio.no/typephotos/lichens/typephotoS.php?f=O-L-001253d_s.jpg
RUSSIA: Nov. Semlja: Nordenfor indløpet til Mashigin fjord, 1921.08.23, Lynge, B. - HOLOTYPE