A novel double-stranded RNA (dsRNA) virus, which was provisionally named Arthrocladiella mougeotii endornavirus (AmEV), was isolated from Arthrocladiella mougeotii, the phytopathogenic fungus infecting Lycium chinense in Beijing, China. The genome of AmEV is 11,683 nucleotides in length with a 5' and 3' non-coding region of 16 and 50 nt, respectively, as well as a single 11,617-nt long open reading frame potentially encoding a putative protein of 3,871 amino acids with conserved Helicase and RNA-dependent RNA polymerase (RdRp) domains. Phylogenetic analysis based on the the amino acid sequence of the RdRp showed that AmEV is most closely related to Erysiphe cichoracearum endornavirus (EcEV).