Deuteromycetous

Deuteromycetous refers to fungi for which a sexual reproductive stage has not been observed. Historically, these organisms were grouped into a formal taxon called Deuteromycota or Fungi Imperfecti, on the basis of the absence of a known teleomorph. In many cases they reproduce asexually by conidia produced on conidiophores, sometimes also by budding, fragmentation, or mycelial reproduction, and they include a wide range of molds and yeasts. The deuteromycetous label is descriptive rather than phylogenetic, and does not reflect a natural clade.

With the advent of molecular systematics, many deuteromycetous fungi have been linked to established lineages within the Ascomycota or Basidiomycota once a sexual state was observed or inferred. Consequently, the formal group Deuteromycota has largely been abandoned in modern taxonomy; however, the term persists in clinical, industrial, and ecological contexts to refer to anamorphic forms or to the portion of a fungus's life cycle that has been observed experimentally. In practice, fungal species now typically receive a single name based on their teleomorph or holomorph when known, with the anamorph name used informally or as a synonym.

Examples of deuteromycetous organisms include many common molds and several human pathogens, such as species traditionally placed in genera like Trichophyton, Microsporum, and Alternaria, as well as yeasts that reproduce predominantly by budding. Understanding these organisms often requires considering both their reproductive biology and their molecular taxonomy.