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Lepraria aurescens Orange & Wolseley |
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Nomenclatural data
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Lichenologist 37(3): 247 (2005); type: Thailand, Chiang Mai Province, Doi Suthep, 18°48'N, 99°56'E, 25 Nov. 1991, P. A. Wolseley & B. Aguirre-Hudson 5001 (BM—holotypus).
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Morphology
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Thallus crustose, leprose; pale grey to pale yellowish grey; usually thin, c. 200 µm; margin diffuse, rarely partly weakly delimited, rim always absent, lobes absent; cortex absent; medulla absent; hypothallus present in places, brown, well developed, forming a loose weft; areoles absent; squamules absent; soredia abundant to sparse in few places, then dark tomentum visible between soredia, fine to medium, 40-100 µm in diam.; surface covered by weft of colourless hyphae; projecting hyphae usually absent, but present on marginal or solitary granules, long, projecting downwards, to 150(-300) µm, mostly dark, grey-brown; isidia-like structures absent. Photobiont green, coccoid.
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Chemistry
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Thamnolic acid. K+ bright yellow, C–, KC–, Pd+ orange-yellow.
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Remarks
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L. nigrocincta is morphologically similar in fine granules, abundant weft of dark hyphae and sometimes yellowish colour; L. atrotomentosa also develops dark hypothallus. L. nigrocincta differs in producing divaricatic acid, L. atrotomentosa has blue-grey thallus with small lobes, contains lecanoric acid, zeorin, atranorin.
Species producing thamnolic acid include L. aurescens, L. nylanderiana, L. pulchra, L. umbricola. L. aurescens has usually thin pale grey to yellowish thallus with brown well developed hypothallus, diffuse margin. L. nylanderiana has usually thick whitish thallus with well developed greyish hypothallus, delimited margin, contains roccellic acid. L. pulchra has thin whitish to pale bluish grey thallus with whitish medulla, delimited margin with a rim, characteristic very short projecting hyphae on soredia. L. umbricola has usually thin green thallus with predominantly no medulla or hypothallus, diffuse margin.
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Ecology and distribution
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Substrate and ecology: bark, sheltered places, dry forest. Distribution: Thailand.
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