Lecanora densa (Śliwa & Wetmore) Printzen

Bryologist, 104, 3: 394, 2001. Basionym: Lecanora varia subsp. densa Śliwa & Wetmore - Bryologist, 103, 3: 486, 2000
Description: Thallus crustose, episubstratic, consisting of 0.1-0.4 mm wide, convex areoles, yellowish beige or ochraceous, sometimes with an ash-grey to dark grey prothallus. Apothecia lecanorine, round to irregular in outline, sessile and constricted at base, 0.3-0.6 mm across, with a beige to orange-brown, mostly flat, dull, pruinose disc, and a weakly prominent, homogeneously coloured, persistent thalline margin. Thalline exciple corticate, 60-120 µm thick laterally, 65-130 µm thick near the base, the cortex 5-20 µm thick laterally, 35-65 µm thick near the base, the hyphae with 1.5-2.5 µm wide lumina, the medullary part rich in algae; proper exciple thin, colourless; epithecium ochre-brown to orange-brown, 7-18 µm high, with many small yellow-brown granules soluble in K; hymenium colourless to yellowish, 40-65 µm high; paraphyses simple or sparingly branched and anastomosing, c. 1 µm thick at mid-level, the apical cells 1.5-2 µm wide; hypothecium colourless in upper part, pale yellow in lower part, 40-60 µm high. Asci 8-spored, clavate, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 8-11 x 4-6 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC- or KC+ pale yellow, P+ bright yellow, UV+ dull orange. Chemistry: usnic, psoromic and 29-O-demethylpsoromic acids.
Note: this species is known from several localities in the Iberian Peninsula, growing on the bark of conifers, mainly Pinus, between 800 and 2500 m; it should be looked for also in Italy, where it could have been confused with L. varia.
Growth form: Crustose
Substrata: bark
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

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Altitudinal distribution:


Predictive model

Curtis Randall Björk – CC BY-SA 4.0
Washington State, Spokane County, near Rosalia Date: 2009-07-09 Photographed from specimen (Björk 19110, UBC) on twigs of Pinus ponderosa in savanna