FINE-STRUCTURE OF ASCOSPOROGENESIS IN CERATOCYSTIOPSIS-PROTEAE

The development and ultrastructure of the ascoma, asci, and ascospores in Ceratocystiopsis proteae were studied and compared with that of ot her genera in Ceratocystis sensu lato. Ascospore delimitation commence d with the formation of double delimiting membranes in the ascus as is true in other species in Ceratocystis s.l. The ascospore wall develop ed between these membranes. In contrast with three wall layers observe d in other species, only two wall layers were observed in C. proteae. Falcate sheaths previously reported in light-microscopic studies were not observed. The falcate appearance of ascospores may be ascribed to the adherence of a matrix to the outermost wall layer during ascospore s release. Differences between this species and others in Ceratocystis s.l. illustrate the problems that can arise from the use of single mo rphological characteristics in the taxonomy of this group. It is accor dingly suggested that the genus Ceratocystiopsis requires taxonomic re vision.