A positive-sense single-stranded RNA mycovirus was isolated from Morchella sextelata strain ZY-1 and designated as "Morchella sextelata endornavirus 1" (MsEV1). The complete genome of MsEV1 was found to be 16,589 nucleotides (nt) in length and to contain a single large open reading frame (ORF) encoding the viral proteins PRK00409, transmethylase, DEXDc, helicase, and RdRP in a polyprotein of 5,477 amino acids. Phylogenetic analysis based on RdRP nucleotide sequences revealed that this endornavirus is a member of the genus Betaendornavirus in the family Endornaviridae.