Lecanora laxa (Śliwa & Wetmore) Printzen

Bryologist, 104, 3: 395, 2001. Basionym: Lecanora varia subsp. laxa Śliwa & Wetmore - Bryologist, 103, 3: 486, 2000
Description: Thallus crustose, yellowish beige, usually endosubstratic, rarely consisting of a few slightly convex areoles. Apothecia lecanorine, 0.3-0.6 mm across, sparse to densely crowded, sessile and strongly constricted at base, with a beige to ochre, concave or rarely flat, whitish-pruinose disc and a thick, strongly prominent, flexuose, persistent thalline margin. Thalline exciple corticate, 40-120 µm wide laterally, 65-160 µm wide at base, the medullary hyphae with 1.5-2 µm thick lumina; cortex 10-30 µm wide laterally, 23-50 µm wide near base; epithecium ochre-brown, 6-13 µm high, finely granular, N-; hymenium colourless, 40-70 µm high; paraphyses simple or weakly branched, up to 1.5 µm thick at mid-level; hypothecium colourless to yellowish, 30-60 µm high. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 7-11 x 4-7 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC- or KC+ faintly yellow, P-. Chemistry: isousnic and usnic acids.
Note: a species described from California and also found on the mountains of Spain, mainly growing on acid bark and lignum, especially of conifers, frequently confused with L. varia; to be looked for in Italy.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual

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Altitudinal distribution:


Predictive model

Jason Hollinger – Public Domain
San Gabriel Peak, San Gabriel Mountains, Los Angeles Co., California, USA.

Curtis Randall Björk – CC BY-SA 4.0
British Columbia, Clearwater Valley Date: 2013-04-07 Corticolous, on young conifer trunk in mixed conifer-deciduous forest