DISCOVERY OF THE GENUS RADIITHECA BROUSMI CHE ET-AL IN THE SARRE-LORRAINE COALFIELD (FRUCTIFICATION OF FILICOPHYTA) AND THE ULTRASTRUCTURALFEATURES OF THE GENUS MICRORETICULATISPORITES

A specimen of the fern fructification Radiitheca BROUSMICHE et al., up to now only known in the Pilsen coalfield (Czech Republic), has been discovered in the late Westphalian D strata of the Sarre Lorraine coal field. Relationships between Radiitheca dobranyana BROUSMICHE et al. a nd Pecopteris waltonii CORSIN are discussed both on paleobotanical and palynological basis. TEM study of the Microeticulatisporites (KNOX) P OTONIE & KREMP macerated from the French and Czech specimens led to th e characterization of the unique layer of the, spore-wall that is the exospore. This investigation has shown: (1) that the ultrastructural f eatures of the spores from both localities are perfectly similar, (2) the nature of the bodies occurring in each lumen that were called ''pu stules'' in Brousmiche et al. (3) and that the lack of these ones is o nly due to preservation or maceration bias. A comparison of the exospo re ultrastructure with that of main groups of living ferns suggests cl ose affinities between the genus Radiitheca and the Gleicheniaceae.