The Colletotrichum gigasporum species complex

In a preliminary analysis, 21 Colletotrichum strains with large conidia preserved in the CBS culture collection clustered with a recently described species, C. gigasporum, forming a clade distinct from other currently known Colletotrichum species complexes. Multi-locus phylogenetic analyses (ITS, ACT, TUB2, CHS-1, GAPDH) as well as each of the single-locus analyses resolved seven distinct species, one of them being C. gigasporum. Colletotrichum gigasporum and its close allies thus constitute a previously unknown species complex with shared morphological features. Five of the seven species accepted in the C. gigasporum species complex are described here as novel species, namely C. arxii, C. magnisporum, C. pseudomajus, C. radicis and C. vietnamense. A species represented by a single sterile strain, namely CBS 159.50, was not described as novel species, and is treated as Colletotrichum sp. CBS 159.50. Furthermore, C. thailandicum is reduced to synonymy with C. gigasporum.