Abstract
Members of Cryptosporella are well-known as common endophytes, and occasionally, as pathogens on a narrow range of hosts in Betulaceae, Tiliaceae and Ulmaceae. Two fresh specimens associated with canker and dieback of Betula platyphylla were made in Beijing, China in 2015. Morphological and multi-gene, combined, phylogenetic analyses (ITS, tef1-α and β-tub) support these speciemens as a distinct and new species of Cryptosporella, from a unique host, Betula platyphylla. Cryptosporella platyphylla sp. nov. is introduced with an illustrated account and differs from similar species in its host association and multigene phylogeny.