DISCOMYCETES: the apothecial representatives of the phylum Ascomycota

Abstract

© 2017, School of Science. Discomycetes are an artificial grouping of apothecia-producing fungi in the phylum Ascomycota. Molecular-based studies have revealed that the discomycetes can be found among ten classes of Ascomycota. The classification of discomycetes has been a major challenge due to the lack of a clear understanding of the important morphological characters, as well as a lack of reference strains. In this review, we provide a historical perspective of discomycetes, notes on their morphology (including both asexual and sexual morphs), ecology and importance, an outline of discomycete families and a synoptical cladogram of currently accepted families in Ascomycota showing their systematic position. We also calculated evolutionary divergence times for major discomycetous taxa based on phylogenetic relationships using a combined LSU, SSU and RPB2 data set from 175 strains and fossil data. Our results confirm that discomycetes are found in two major subphyla of the Ascomycota: Taphrinomycotina and Pezizomycotina. The taxonomic placement of major discomycete taxa is briefly discussed. The most basal group of discomycetes is the class Neolectomycetes, which diverged from other Taphrinomycotina around 417 MYA (216–572), and the most derived group of discomycetes, the class Lecanoromycetes, diverged from Eurotiomycetes around 340 MYA (282–414). Further clarifications based on type specimens, designation of epitypes or reference specimens from fresh collections, and multi-gene analyses are needed to determine the taxonomic arrangement of many discomycetes.