Allocetraria ambigua (Bab.) Kurok. & Lai
Nomenclatural data
Bull. Nat. Sci. Mus. (Tokyo) B 17: 60, 1991. - Cetraria ambigua Bab., Hook. Journ. Bot. 4: 244, 1852. - Type: India, Bompras, Garhwal, Himalaya, alt. 16 000 ft., Strachey & Winterbottom, no. 6 (BM - lectotype, selected by D.D.Awasthi, 1980; seen - the type material also contains a small branch of A. stracheyi)
Morphology
Thallus suberect to erect foliose, forming 2-3 cm high tussocks, upper surface pale yellow, smooth or slightly rugose, with sparse concolorous rhizines; lobes comparatively wide (up to 3 mm), lobe margins and tips concave; pseudocyphellae marginal on the lower surface, in the form of small spots or fragmentary lines; upper cortex c. 30 µm, composed of 4-6 layers of cells, smaller near the surface; medulla always white, 120-160 µm.
Apothecia rare, marginal, with brown disc, up to 5 mm in diameter; exciple 30-35 µm thick; asci clavate, µm; ascospores broadly ellipsoid, 7-8 x c. 5 µm; pycnidia marginal to submarginal, immersed or on emergent projections, dark pigmented; pycnoconidia 12-14 x 0.5-1 µm.
Chemistry
Usnic acid (+/-) in the cortex; fatty acids (lichesterinic and protolichesterinic) in the medulla; secalonic acids (A and/or C) may also be present.
Remarks
Allocetraria ambigua is easily recognized on the broad lobes with rather narrow, concave apices (Fig.). Morphologically it is sometimes very similar to Flavocetraria nivalis and those two species also often grow together but the latter has wider and more reticulate lobes. More or less concave habit of lobes is a good character for separating it from Allocetraria stracheyi.
Ecology and distribution
The species is endemic to Himalaya growing on the ground in alpine areas.
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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