A revision of the genus Trichoderma. I. Section Longibrachiatum sect. nov.

Abstract

Variation in strains assignable to the Trichoderma longibrachiatum Rifai and T. pseudokoningii Rifai species aggregates was studied. Morphological similarities allow their assignment to one section in Trichoderma, sect. Longibrachiatum, characterized and differentiated from other species of Trichoderma by the sparsely branched conidiophores having a high proportion of solitary phialides. Cultural characteristics include very rapid growth and the production of characteristic bright yellow-green pigments visible in the colony reverse. Two new species are described in the section: Trichoderma citrinoviride Bissett has ellipsoidal conidia smaller than in the other species and conidiophore branching similar to that in T. pseudokoningii; Trichoderma atroviride Bissett has relatively large, ellipsoidal conidia and a very sparse branching system with curved or sinuous conidiophores, branches, and phialides.