Species of Diaporthe (Diaporthaceae, Diaporthales) associated with Alnus nepalensis leaf spot and branch canker diseases in Xizang, China

<i>Alnusnepalensis</i> is an important tree species in the Himalayas with significant ecological and economic roles. During disease surveys in Xizang, China, we observed leaf spot and branch canker symptoms on this tree. Fungal isolates associated with these diseases were collected and identified based on morphological characteristics and phylogenetic analysis of ITS, <i>cal</i>, <i>his3</i>, <i>tef1</i>, and <i>tub2</i> sequences. As a result, <i>Diaporthealnicola</i> <b>sp. nov.</b> and <i>D.amygdali</i> were identified from the leaf spots, while <i>D.linzhiensis</i> was identified to be associated with the cankered branches. This study identifies pathogenic species from alder trees, providing a foundation for future disease management and forest health research.