Species of Colletotrichum are commonly found in many plant hosts as pathogens, endophytes and occasionally saprobes. Twenty-two Colletotrichum strains were isolated from three Dendrobium species - D.cariniferum, D.catenatum and D.harveyanum, as well as three unidentified species. The taxa were identified using morphological characterisation and phylogenetic analyses of ITS, GAPDH, ACT and ß-tubulin sequence data. This is the first time to identify endophytic fungi from Dendrobium orchids using the above method. The known species, Colletotrichumboninense, C.camelliae-japonicae, C.fructicola, C.jiangxiense and C.orchidophilum were identified as fungal endophytes of Dendrobium spp., along with the new species, C.cariniferi, C.chiangraiense, C.doitungense, C.parallelophorum and C.watphraense, which are introduced in this paper. One strain is recorded as an unidentified species. Corn meal agar is recommended as a good sporulation medium for Colletotrichum species. This is the first report of fungal endophytes associated with Dendrobiumcariniferum and D.harveyanum. Colletotrichumcamelliae-japonicae, C.jiangxiense, and C.orchidophilum are new host records for Thailand.
Keywords: Colletotrichum; Dendrobium; Endophytic fungi; multi-loci; new species.