Microthyrium ilicinum  

Mycelium superficial, abundant, composed of much-branched pale yellow hyphae ca 1.5 µm broad with numerous swollen cells up to 3 µm connected to the subcuticular haustoria.
Anamorph: not known.
Teleomorph: ascomata thyriothecia, to 270 µm diam., amphigenous, circular, scattered but often confluent. Upper wall composed of radiating rows of pale brown quadrilateral cells 2-4 x 3-5 µm, scarcely darkened at the centre, with the marginal cells divided and elongated to form a slight fringe. Ostiole 8-10 µm diam. Interascal tissue absent. Asci 36-56 x 8-9 µm, cylindrical to narrowly pyriform with a thickened rounded apex, fissitunicate, 8-spored. Ascospores arranged biseriately, 11-14 x 2.5-3.5 µm, ellipsoidal to narrowly clavate, straight, 1-septate, the upper cell slightly longer and broader than the lower cell, hyaline, smooth, with several small guttules disappearing at maturity, with three or four apical horizontally radiate cilia ca 10 µm long.