Discomycetes

Abstract

The Discomycetes are a heterogeneous assemblage of unitunicate Ascomycota that have been characterized by the production of open ascomata, apothecia. Although the apothecial ascomycetes have long been classified as the Discomycetes morphologically, such a classification today serves to segregate these fungi but does not reflect current knowledge of their relationships to one another or to the other members of the Ascomycota. The distinction among groups has been based on morphological and cytological studies and this information has led to a classification scheme that has generally been followed. Molecular phylogenetic studies using DNA sequence data have shown that the orders included here form several distinct and, in some cases, only distantly related lineages. Taking into account recent ideas, the Discomycetes, as treated here, include taxa that typically produce apothecia, but also those with closed ascomata such as the Erysiphales which are included here even though their affinities remain questionable. In all, 13 orders are included: Caliciales, Cyttariales, Erysipales, Gyalectales, Helotiales, Lichinales, Lecanorales, Mediolariales, Neolectales, Ostropales (including Graphidiales), Pezizales, Rhytismatales, and Triblidiales. In certain cases, the distinction between these orders is unclear; in other cases, the orders are heterogeneous and ultimately will need to be revised — a process that is only beginning at this time. These orders are remarkable in their variety of life histories, of ascus and ascomatal structure, and in associations with other organisms. The divide between the classification of lichenized and nonlichenized taxa has begun to narrow, but a complete and comprehensive classification has yet to be articulated.