Allocetraria flavonigrescens Thell & Randl.

Nomenclatural data
Typus: Nepal, Langtang Area, Pemdang Karpo, alt. 4620 m, G.& S. Miehe, 29.09.1986, no. 13 056 (GZU - holotypus)
Morphology
Thallus subfruticose to foliose, suberect to prostrate, up to 4 cm, irregularly branched; lobes narrow, convex, 1-3 mm broad, thick; upper surface pale yellow, lower surface brown to black, strongly wrinkled; rhizines and pseudocyphellae absent; upper cortex c. 30 µm, composed of 4-6 layers of cells, smaller near the surface; medulla white, 170-280 µm, composed of 3-4 layers of equal-sized cells.
Apothecia not seen; pycnidia marginal to laminal, immersed or on short projections, dark pigmented; pycnoconidia 12-17 x 0,5-1 µm.
Chemistry
Usnic acid in the cortex; an unknown fatty acid (but not of lichesterinic-protolichesterinic type, neither caperatic acid), and fumarprotocetraric acid in the medulla. An unknown violet pigment is also noticed.
Remarks
Ecology and distribution
This species often grows on the ground in the alpine tundra in Himalaya above 4000 m, occasionally at the base of shrubs. A. flavonigrescens is known till now from two localities in Nepal only.
Literature:
Randlane, T. & Saag, A. 1993. | Randlane, T. & Saag, A. 2004. | Randlane, T., Saag, A. & Obermayer, W. 2001. | Randlane, T., Saag, A. & Thell, A. 1997. | Thell, A., Randlane, T., Kärnefelt, I., Gao, X. & Saag, A. 1995.
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