Trichoderma: systematics, the sexual state, and ecology.

Area of Science:

• Mycology
• Fungal Taxonomy
• Molecular Phylogenetics

Background:

• The fungal genus Trichoderma has a complex taxonomic history with numerous described species.
• Several species of Hypocrea have been linked to unnamed Trichoderma anamorphs, complicating classification.
• Morphological characters alone are insufficient for accurate species delimitation in Trichoderma.

Purpose of the Study:

• To chart the development of genus and species concepts in Trichoderma.
• To investigate the phylogenetic relationship between Trichoderma and Hypocrea.
• To propose a unified nomenclature for the congeneric Trichoderma/Hypocrea complex.

Main Methods:

• Phylogenetic analyses incorporating 83 taxa of Trichoderma and their teleomorphs, Hypocrea spp.
• Molecular phylogenetic analyses using DNA-based characters (translation-elongation factor EF-1alpha and internal transcribed spacer rDNA).
• Review of existing taxonomic literature and species descriptions.

Main Results:

• Phylogenetic analyses demonstrate that Trichoderma and Hypocrea are congeneric.
• Sexual and asexual lineages within the complex are not independent.
• Molecular data has revealed more species than recognized by morphology alone.
• New species of Trichoderma continue to be discovered in diverse ecological niches.

Conclusions:

• A single generic name, preferably Trichoderma, should be adopted for the Trichoderma/Hypocrea complex.
• DNA-based characters are indispensable for modern fungal species identification.
• Further exploration of new niches and geographic locations will yield more undescribed Trichoderma species.