FOURIER-TRANSFORM RAMAN MICROSCOPY OF THE APOTHECIA OF CHROODISCUS-MEGALOPHTHALMUS (MULL. ARG.) VEZDA AND KANTVILAS

The lichen Chroodiscus megalophthalmus still attached to its siliceous substratum has been studied using FT-Raman microscopy. White deposits in the margins of the apothecia were identified as calcium oxalate mo nohydrate. White crystalline material at the apothecial disk surface a nd outer surface of the prominent wart-like protuberances is clearly i dentifiable and shows the presence of crystalline calcium oxalate mono hydrate only. However, within the hymenium and below the surface of th e wart-like protuberances, there is a mixture of calcium oxalate mono- and di-hydrates with a preponderance of the dihydrate. It is tentative ly suggested that calcium oxalate has a metabolic role in regulating w ater within the thallus and as a deterrent to grazing invertebrates.