Three new species of Colletotrichum (Glomerellales, Glomerellaceae) associated with walnut (Juglans regia) anthracnose from China

<i>Colletotrichum</i> species are significant pathogens of various economic plant hosts worldwide. In this study, 45 <i>Colletotrichum</i> isolates were obtained from symptomatic walnut leaves of walnut anthracnose in Shaanxi and Sichuan Provinces. In conjunction with morphological evidence and multi-gene phylogenetic analyses of internal transcribed spacer (ITS), actin (<i>act), chitin synthase 1 (chs1), glyceraldehyde-3-phosphate dehydrogenase (gapdh</i>) and beta-tubulin (<i>tub2</i>) sequences support the introduction of three new species, namely <i>Colletotrichumcordae</i>, <i>C.guangyuanense</i> and <i>C.juglandium</i>. Five species of <i>Colletotrichum</i> were identified to be <i>C.fioriniae</i> of the <i>C.acutatum</i> species complex, <i>C.karsti</i> of the <i>C.boninense</i> species complex, <i>C.gloeosporioides</i>, <i>C.mengyinense</i> and <i>C.siamense</i> of the <i>C.gloeosporioides</i> species complex. The three new species are described and illustrated in this paper and compared with taxa in the <i>Colletotrichumgloeosporioides</i> species complex. The current results improve the understanding of <i>Colletotrichum</i> species causing walnut anthracnose in China.