Allocetraria endochrysea (Lynge) Kärnefelt & A. Thell
Nomenclatural data
Nova Hedwigia 62: 507, 1996. – Dactylina endochrysea Lynge, Skr. Svalbard Ishavet (Oslo) 59, Suppl. 5: 62, 1933. – Type: China, Yunnan, Mt. Li Kiang, alt. 4 000 m, 1886, R. P. Delavay (H-NYL 35806 – holotype, O – isotype)
Typical characters. Thallus radial symmetric, slightly inflated, becoming arachnoid in the center. Medulla coloured (deep yellow to orange). Pycnidia emergent.
Contains usnic acid in the cortex and hybocarpone and secalonic acid B in the medulla. Literature data about medullary compounds are various – Follmann et al. (1968) mention dufourin and endochrysin; Kärnefelt & Thell (1996) add lichesterinic and protolichesterinic acids. The latest HPLC analysis by Elix established that in addition to usnic acid, hybocarpone (major) and secalonic acid B (minor) were present in our Tibetan specimen. Hybocarpone is a novel cytotoxic naphthazarin derivative which was recently described from Lecanora hybocarpa (Tuck.) Brodo (Ernst-Russell et al. 1999). Endochrysin is probably an older name for the complex of secalonic acids. Chemical structure and position of dufourin is uncertain (Culberson 1970).
The taxon was originally described by Lynge (1933) as a Dactylina because of its morphological similarity to D. madreporiformis. Both species were transferred to Allocetraria by Kärnefelt & Thell (1996), mainly on the basis of a very distinctive type of filiform pycnoconidia and the medullary chemistry. Apothecia have not previously been observed. Our single specimen was fertile; apothecia terminal, c. 2–5 mm in diameter, with a brown disc and rather thick thalline margin; mature asci not found. The species can be separated from A. madreporiformis by the coloured medulla.
Ecology and distribution
Endemic to the Himalayas; has been found in China in Sichuan and Yunnan provinces (Follmann et al. 1968; Wei 1991; Kärnefelt & Thell 1996). Not recorded from Tibet but most probably occurs there. Grows on soil at altitudes of 4000–4700 m.
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.