Leotiomyceta represents all the filamentous ascomycete fungi (Pezizomycotina), excluding the classes Pezizomycetes and Orbiliomycetes. It is well supported in several studies comparing DNA sequences in fungi.[1][2] It has originally been proposed as a superclass[3] but later was proposed as a rankless taxon for any well supported group above class (together with Saccharomyceta, Dothideomyceta, and Sordariomyceta[4]). Rankless taxa do not strictly follow the rules for taxonomic classifications in plants and fungi (ICBN) and therefore these names are informal, although they appear to reflect natural groups.