Allocetraria stracheyi (Bab.) Kurok. & Lai

Nomenclatural data
Bull. Nat. Sci. Mus. (Tikyo) B 17: 62. - Evernia stracheyi Bab., Hook., Journ. Bot. 4: 244, 1852. - Type: India, Kumaon, Gori River, alt. 4700 ft., Strachey & Winterbottom (H-NYL-36055, lectotype; seen).
Platysma everniellum Nyl., Memoir. Soc. Imp. Scienc. Natur. Cherbourg 5: 100, 1857 (based on Evernia stracheyi Bab.). - Cetraria everniella (Nyl.) Krempelh., Verhandl. Zool.-bot. Gesellsch. Wien 18: 315, 1868.
Cetraria potaninii Oxn., Journ. Cycle Bot. l’Akad. Sci. d’Ukraine: 168, 1933. - Allocetraria potaninii (Oxn.) Randl. & Saag, Mycotaxon 44:492, 1992. - Type: China, Tibet, Montes Kamenses, inter stats. Tasso et Pen-cza mu, Tassa-schanj, Potanin, 31.05.1893 (KW, holotype; seen).
Thallus prostrate to suberect foliose, up to 5 cm, upper surface pale yellow, smooth; lower surface pale yellow to brown, wrinkled, with sparse marginal rhizines; lobes convex, comparativly thick; upper and lower cortex c. 30 µm, composed of 3-5 layers of cels, smaller near the surface; medulla white to orange, 200-230 µm thick.
Apothecia rare, marginal, with brown disc, up to 5 mm in diameter; exciple µm thick; mature asci extremely rare, clavate, µm; ascospores c. 5 x 5 µm; pycnidia marginal, immersed or on emergent projections, dark pigmented; pycnoconidia 12-14 x 0.5-1 µm.
Usnic acid in the cortex; fatty acids (lichesterinic and protolichesterinic) and secalonic acids (A and C) together with other related pigments (e.g. endocrocin) in the medulla.
The species is somewhat similar to A. ambigua but differs in having more narrow, plane or convex lobes with a wrinkled lower surface. Oxner (1933) described Cetraria potaninii on material from Tibet. He indicated that the type was preserved in Leningrad (LE). It was not present there lately and feared therefore that the type material was destroyed during the second world war. Fortunately it was found in Kiew (KW) and kindly sent to us. After having studied the material, we have to consider this species as a synonym to Allocetraria stracheyi.
Ecology and distribution
A. stracheyi has a rather wide distribution. It is terricolous in the alpine tundra (above 3000 m) in India, Nepal, China, Taiwan and Mongolia.
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.