STIGMIDIUM LECIDELLAE SP-NOV AND NOTES ON THE GENUS STIGMIDIUM (NON-LICHENIZED LICHENICOLOUS FUNGI, ASCOMYCETES)

Stigmidium lecidellae Triebel, Roux et Le Coeur sp.nov., a mild pathog enic lichenicolous fungus growing on the apothecia of Lecidella elaeoc hroma (Ach.) M. Choisy is described in detail and compared with other species of Stigmidium that grow on the apothecia of the host. The stai ning of parts of cell walls with cresyl blue is constant at species le vel and, therefore, is taxonomically relevant in the genus Stigmidium. The dye also allows to distinguish some ultrastructural details of th e vegetative hyphal cells, asci, and ascospores. Among the fungi speci es growing on the apothecia of lichens, three groups are distinguished on the basis of their hamathecial structure, one of which should be e xcluded from the genus Stigmidium and included in the genus Spharellot hecium. A key to the determination of the species is presented.