CYTOLOGY OF THE ASCUS IN ACHAETOMIUM GLOBOSUM AND A. LUTEUM

The cytology of the ascus in Achaetomium globosum and A. luteum was studied using BAC (butanol-acetic acid-chromic acid, 3:2:1) fixative and propiono-iron-haematoxylin stain. Ascus initial is the binucleate penultimate cell of the crozier. In A. luteum pachytene chromosomes are very long, easily countable, and the nucleolar organizer is clearly distinct. In general, divisions I and III stages are prominent in both the species studied, while division II stages are less frequent. Division IV starts during the delimitation of ascospores and continues in the mature ascospores. The chromosome number as counted from metaphase III configurations in A. globosum and pachytene configurations in A. luteum is 7 (n=7).