ASCOSPORE ULTRASTRUCTURE OF PLEOSPORA-GAUDEFROYI (PLEOSPORACEAE, LOCULOASCOMYCETES, ASCOMYCOTINA)

Ascospore and spore appendage ultrastructure in Pleospora gaudefroyi i s described. Ascospore walls comprise a three-layered mesosporium with in which electron-dense bodies (melanin?) are deposited in two layers (W2, W3), a tripartite episporium (W4), and an outer mucilaginous shea th (exosporium?). The electron-dense inclusions in the mesosporium are compared with those in the conidia of Altenaria brassicicola and asco spores of Carbosphaerella leptosphaerioides. In the unitunicate marine Ascomycetes, ascospores with a sheath are uncommon, whereas in the Lo culoascomycetes many species have such ascospores. The sheath in P. ga udefroyi is compared with those of Paraliomyces lentiferus, Massarina thalassiae, and Massarina armatispora (all Loculoascomycetes).