Plectomycetidae

Plectomycetidae is an informal grouping of fungi within the Ascomycota phylum. This classification is primarily based on morphological characteristics, specifically the formation of cleistothecia, which are globose, closed ascocarps. The asci are typically produced within these structures, and they contain the ascospores. Plectomycetidae is not a recognized formal taxonomic rank within the modern phylogenetic classification of fungi, which relies heavily on molecular data. Instead, it represents a collection of diverse fungal orders that share the convergent evolutionary trait of cleistothecial development.

Fungi traditionally placed within Plectomycetidae exhibit a wide range of ecological roles, including saprotrophic, parasitic, and symbiotic relationships. Many are found in soil, on decaying organic matter, or associated with plants and animals. Some well-known genera that were historically considered part of Plectomycetidae include Aspergillus and Penicillium, both of which are important in biotechnology and medicine, as well as in causing spoilage and disease. Other examples include Eurotium, Talaromyces, and Neosartorya.

The study of Plectomycetidae has been historically significant in mycology, contributing to our understanding of fungal reproductive structures and their diversity. However, modern phylogenetic analyses have revealed that the cleistothecial ascocarp has evolved independently multiple times across different fungal lineages. Therefore, the group is considered polyphyletic, meaning it does not represent a single, shared evolutionary ancestor. As such, Plectomycetidae is largely superseded by more precise classifications based on genetic relationships.