The easiest way to identify Trichoderma species is to use sequencing of ITS and EF1alpha genes. First you amplify ITS and EF using universal primers. Clone or directly sequence the amplicon. Later on take the help from barcoding website to look for species. you can use NCBI as well but some time the sequence submitted are not validated.
As for as morphology is considered, it is difficult either at mycelial or at conidal level. You should have expertise in mycology then only it is possible . If you want to do species identification then try IARI, New Delhi (Dr. Pratiba Sharma) the current HOD of Division of Plant Pathology. Still while publishing you may have to use PCR technology as proof.