A morphological and molecular perspective of Trichoderma viride: Is it oneor two species?

Trichoderma (Aseomycetes, Hypocreales) strains that have warted conidia are traditionally identified as T, viride, the type species of Trichoderma, Ho wever, two morphologically distinct types of conidial warts (I and II) have been found. Because each type corresponds to a unique mitochondrial DNA pa ttern, it has been questioned whether T, viride comprises more than one spe cies. Combined molecular data (sequences of the internal transcribed spacer 1 [ITS-1] and ITS-2 regions and of part of-the 28S rRNA gene along with re sults of restriction fragment length polymorphism analysis of the endochiti nase gene; and PCR fingerprinting), morphology, physiology, and colony char acteristics distinguish type I and type II as different species. Type I cor responds to "true" T, viride, the anamorph of Hypocrea rufa, Type II repres ents a new species, T. asperellum, which is, in terms of molecular characte ristics, close to the neotype of T. hamatum.