Eight Colletotrichum species, including a novel species, are associated with areca palm anthracnose in Hainan, China

Colletotrichum is one of the most important genera of plant-pathogenic fungi affecting numerous species, particularly tropical and subtropical crops and fruit trees. In this study, forty-three strains of Colletotrichum were isolated from areca palm leaves with anthracnose symptoms in eleven areca palm plantations in eight counties of Hainan, China. Based on the morphology, phylogenetic analysis of six loci (ITS, ACT, CHS-1, GAPDH, TUB2 and ApMat) and pathogenicity tests, eight Colletotrichum species were distinguished, comprising five previously known species (C. cordylinicola, C. fructicola, C. gloeosporioides, C. siamense and C. tropicale), one unidentified species of Colletotrichum and a new species, C. arecicola, in the gloeosporioides species complex and C. karstii in the boninense species complex. Colletotrichum siamense was the most common species found in areca palm in Hainan, followed by C. arecicola. Pathogenicity tests showed that all the eight species could cause anthracnose symptoms on areca palm leaves using a wound inoculation method and that the isolates from the gloeosporioides species complex caused larger lesions than the isolates from the boninense species complex. Further research is needed to understand the epidemiology of these pathogenic species on areca palm in order to develop management strategies.