Species delimitations and taxonomic groupings within the Fossombroniineae have traditionally relied on variations in spore wall architecture and consequently, many decriptors of spore wall morphology have been published. In most studies spores have been described on the basis of features resolved at the level of optical microscopy. With the increased resolution of SEM, many of the early descriptors are no longer applicable. For example, the epithet of Fossombronia foveolata Lindb. presumably described a foveolate distal spore wall surface, which in more recent times has been described by various other authors as reticulate, areolate, or even alveolate. To resolve the inconsistencies in spore wall terminology, we have compiled representative SEM micrographs of both distal and proximal spore wall architectures, prepared as part of a worldwide monograph of the Fossombroniineae. A variety of modern and classical treatments of pollen and spore morphology were consulted to identify the most appropriate descriptor for each of the major architectural patterns found in the group. These results are presented as a photo atlas, in which ten major distal face architectural designs are recognized. While there is less variation in proximal face designs, the systematically significant features of this face will also be presented.

Key words: Fossombroniineae, liverwort spores, spore wall architecture, terminology