Morphological and macromolecular characterization of Hypocrea schweinitzii and its Trichoderma anamorph

Abstract

Morphological, cultural, and isozyme analyses were used to determine variation in the Trichoderma anamorph of Hypocrea schweinitzii, a presumably unequivocal species of Trichoderma, and to assess whether the anamorph of H. schweinitzii can be assigned to T. longibrachiatum, T. reesei or T. pseudokoningii. The results of these studies indicate that H. schweinitzii comprises at least three distinct and taxonomically separable holomorph taxa that coincide with the geographical origin of the collections. The name H. schweinitzii can be applied to Northern Hemisphere and H. jecorina to tropical American collections; while taxonomically distinct, no name was given to a Chinese collection. The holomorphs of H. schweinitzii, H. jecorina, and the Chinese collection showed little intraspecific variation in morphology of the teleomorph or anamorph, or in cultural and isozyme characters. They exhibited no more variation than was noted in the ex type cultures of the named Trichoderma species. None of the named Trichoderma species coincided with any of the Hypocrea species studied. It is concluded that Trichoderma species in general can be narrowly defined but that morphology alone might not suffice to allow the identification of species. The synonymy of T. reesei under T. longibrachiatum is not supported by morphological and cultural observations and by isozyme data and it is therefore not accepted.

Key Words:

• Ascomycetes
• Hypocreales
• Hypocrea
• Trichoderma
• taxonomy