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Lepraria rigidula (de Lesd.) Tønsberg |
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Nomenclatural data
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Sommerfeltia 14: 205 (1992); type: United Kingdom, Scotland, Perth, Pitlachry, byside of R. Tummel, Jun. 1914, J. McAndrew (E—holotypus). Crocynia rigidula de Lesd., in Hue, Bull. Soc. Bot. France 71: 331 (1924).
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Morphology
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Thallus crustose, leprose, with cottony to powdery appearance; whitish grey to pale bluish grey; usually thick, soft, lax, not very firmly attached to the substrate; shape irregular, small to large, fused patches can be several dm in diam.; margin diffuse, lobes absent; cortex absent; medulla sometimes present, poorly to well developed, lax, white; lower surface absent; prothallus absent; areoles absent; squamules absent; soredia abundant, mostly fine, sometimes coarse, up to 60(-100) µm in diam., loosely or very loosely packed; wall usually distinct; projecting hyphae present, very long or long at least on some soredia, up to 120 µm; consoredia sometimes present, up to 300 µm in diam.; isidia-like structures absent. Photobiont green, coccoid, up to 20 µm in diam.
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Chemistry
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Atranorin and nephrosteranic acid. Very rarely unidentified anthraquinones have been found (Flakus & Kukwa 2007). K– or + faint yellow, C–, KC–, Pd–.
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Remarks
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Several species can contain atranorin and fatty acids, see discussion under L. jackii. L. rigidula is unique among them in having lax cottony thallus, loosely packed soredia, very long projecting hyphae, and containing a rare fatty acid, nephrosteranic acid. L. rigidula was regarded as a synonym of L. alpina (sub nomine Leproloma cacuminum by Laundon (1992), but was resurrected as a separate species by Tønsberg (1992).
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Ecology and distribution
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Substrate and ecology: mainly tree bark, also mosses on various substrata, rarely rock, soil or wood, very rarely lichens; shaded but usually open situations. Distribution: Asia, Europe, North Africa, North America.
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