Phylum Ascomycota Caval.-Sm. (1998) - sac fungi
   Subphylum Pezizomycotina O.E. Erikss. & Winka (1997)
     Class Sordariomycetes O.E. Erikss. & Winka (1997)
       Subclass Hypocreomycetidae O.E. Erikss. & Winka (1997)
         Order Hypocreales Lindau (1897)
           Genus Bulbithecium Udagawa & T. Muroi (1990), incertae sedis