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Lepraria diffusa (J.R. Laundon) Kukwa |
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Nomenclatural data
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Ann. Bot. Fennici 39(3): 226 (2002); type: Finlandia, Oulu, Paltamo, Melalahti, Viilonkallio, 11. Oct. 1959, A. J. Huuskonen & L. Heikkinen (BM—holotypus). Leproloma diffusum J.R Laundon, Lichenologist 21(1): 16 (1989).—Lepraria diffusa var. chrysodetoides (J.R. Laundon) Kukwa, Ann. Bot. Fennici 39(3): 226 (2002).—Leproloma diffusum var. chrysodetoides J. R. Laundon, Lichenologist 21(1): 18 (1989).
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Morphology
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Thallus crustose, leprose, with powdery, rarely slightly cottony appearance; greenish white, sometimes greenish yellow with occasional orange-yellow patches; medium to thick, soft, firmly attached to the substrate; shape irregular; margin diffuse, rarely delimited, lobes absent; cortex absent; medulla present, usually thick, sometimes thin, white; hypothallus sometimes present, weakly developed, whitish grey to brownish; areoles absent; squamules absent; thallus surfaces without soredia rarely present, medulla exposed but only in small patches or fissures, soredia abundant, coarse, up to 100 µm in diam., rather loosely packed; projecting hyphae sometimes present, short; isidia-like structures absent. Photobiont green, coccoid, up to 15 µm in diam.
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Chemistry
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4-oxypannaric acid 2-methylester, 4-oxypannaric acid ± (minor to trace), pannaric acid methylester ± (trace), pannaric acid 2- methylester ± (trace), pannaric acid ± (trace) and other dibenzofurans ± in traces (see Elix & Tønsberg 2006), rarely also atranorin and/or roccellic acid or very rarely rangiformic acid (Baruffo et al. 2006). K– or + yellow slowly becoming orange, C– or + yellow, KC– or + yellow, Pd+ reddish orange.
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Remarks
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L. eburnea, L. lobificans may have similar morphology but do not produce dibenzofuranes. L. diffusa var. chrysodetoides was subsumed within var. diffusa by Kukwa (2006b). It was described based on yellow pigment by Laundon (1989) but detection of this is problematic, and the substance, possibly the diagnostic dibenzofurane itself, appears to be present also in main variety (Kukwa 2006b). L. vouauxii produces dibenzofuranes and is sometimes also morphologically similar. However, L. diffusa is more powdery, with less or no patches with exposed medulla, contains 4-oxypannarix acid 2-methylester as major substance. Sometimes L. leprolomopsis, L. eburnea, L. lobificans L. nivalis, L. nylanderiana and L. vouauxii may be morphologically similar to L. diffusa, see the discussion under L. leprolomopsis.
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Ecology and distribution
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Substrate and ecology: mosses on calcareous rock, calcareous rock, rarely bark or soil; mostly shaded and sheltered places. Distribution: Asia, Europe, North America.
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