Anamorph: Neomarssoniella juglandis (Lib.) U. Braun (1991). Conidiomata acervular, 70-200 µm diam, developing between the host cuticle and epidermis. Conidiogenous cells 5-7 x 2-3 µm, proliferating percurrently. Conidia 18-24 x 3-4 µm, curved with tapered ends (crescent-shaped), hyaline, smooth, 1-septate. A microconidial morph may also be present, with cylindrical aseptate conidia 6-12 x ca 1 µm according to Monod (1983).
Teleomorph: Stromata absent. Ascomata 170-300 µm diam, the neck central, 150-250 x ca 50 µm and straight. Peridium 15-30 µm thick, composed of 4-5 layers of cells. Interascal tissue absent. Asci 45-60 x 8-14 µm, 8-spored. Ascospores 19-23 x ca 3.5 µm, narrowly ellipsoidal-fusiform, with somewhat pointed ends, straight, septum median, without appendages, each cell containing 2-3 guttules or numerous small inclusions.