XVI International Botanical Congess

Aquatic ascomycetes share many morphological characters showing their adaptation to the aquatic environment. Convergent evolution of the common morphological characters was tested using ssrDNA sequences. Common morphological characters of aquatic ascomycetes such as sigmoidal ascospore shape, presence of ascospore appendages or gelatinous sheaths, deliquescent asci, presence of catenophyses and arrangement and shape of asci were mapped on phylogenetic trees of freshwater, marine and terrestrial ascomycetes. Most characters appear to have evolved in more than a single evolutionary line. Exceptions are the presence of catenophyses and some types of appendages that are found exclusively in the Halosphaeriales. Ascus deliquescence varies within species and across evolutionary lines.