A COMPARATIVE-STUDY ON STRUCTURE AND FUNCTIONALITY OF ASCI IN SPECIESOF RHIZOCARPON (LECANORALES, ASCOMYCETES)

A comparative study concerning about twenty species of Rhizocarpon rev ealed, that the genus has a uniform major type of ascus, but shows dif ferences in the amyloid structures of the tholus. These differences ar e considered to be due to functional adaptations in the context of asc us dehiscence and ascospore release. In order to maintain the function ality of oligosporic asci, the enlargement of spores is compensated by modified amyloid tholus structures. It is mainly the ascospore size, that influences tholus and especially the cap heights. The mean values of the ratio between these two variables ('cap index') significantly differ between species with octosporic and those with oligosporic asci . This interdependence is being proven by statistical means.