Phylum Ascomycota Caval.-Sm. (1998) - sac fungi
   Subphylum Pezizomycotina O.E. Erikss. & Winka (1997)
     Class Sordariomycetes O.E. Erikss. & Winka (1997)
       Subclass Xylariomycetidae O.E. Erikss. & Winka (1997)
         Order Xylariales Nannf. (1932)
           Family Clypeosphaeriaceae G.Winter (1886) see Family Xylariaceae Tul. & C.Tul. (1861)
             Genus Crassoascus Checa, Barrasa & A.T. Martínez (1993)