Traditionally, most of its members were included in the
loculoascomycetes, which is not part of the currently accepted classification.[4] This indicates that several traditional morphological features in the class are not unique and DNA sequence comparisons are important to define the class.[5]
The designation loculoascomycetes was first proposed for all fungi which have
ascolocular development.[6] This type of development refers to the way in which the
sexual structure, bearing the sexual spores (
ascospores) forms. Dothideomycetes mostly produce flask-like structures referred to as
pseudothecia, although other shape variations do exist (e.g. see structures found in
Hysteriales). During ascolocular development pockets (
locules) form first within the vegetative cells of the fungus and then all the subsequent structures form. These include the
asci which, superficially, have a thicker outer layer through which a thinner inner layer ‘bursts’, like a jack-in-a-box to release the spores. These asci are therefore referred to as
bitunicate (superficially, two layers) or
fissitunicate (referring to spore release). After several
DNA sequence comparisons it is now clear that another group of fungi which share these characteristics are distantly related. These are the
"black yeasts" in subclass
Chaetothyriomycetidae (
Eurotiomycetes).[7] This means that loculoascomycetes did not constitute
a natural group.
^LoBuglio KF, Berbee ML, Taylor JW (1996). "Phylogenetic origins of the asexual mycorrhizal symbiont Cenococcum geophilum Fr. and other mycorrhizal fungi among the ascomycetes". Molecular Phylogenetics and Evolution. 6 (2): 287–94.
doi:
10.1006/mpev.1996.0077.
PMID8899729.