Ultraestructura de la exina en ejemplares carboníferos de Lundbladispora (Lícofíta), La Rioja, Argentina

Abstract

The cavate microspore Lundbladispora, found in Carboniferous strata of the Tupe Fonnation, La Rioja province,Argentina, has a two layered exine. The outer thick spongylayer has extemal minute perforations and sculptural elements: its ultrastructure is alveolar. The inner layer is thin, continuous, often detached from the outer spongy layer. Spores are strongly compressed and so are the spaces between sporopollenin muri of outer layer. Exine compact areas are the result of fossilization. Comparing with fossil laxa, Lundbladispora resembles more the mesozoic Densoisporites: it has been found in the heterosporous cone Skilliostrobus from the Australian Permian and Triassic strata. Considerations are made about the probable function of the spongy exine as related to the paleonvironments and post-glacial climatic régime that characterized the late Carboniferous of the Paganzo Basin ..