Asteromassaria macrospora  

Anamorph: conidiomata acervular, 200-250 µm diam., subperidermal, brown, with a wall composed of dark thick-walled angular cells, dehiscing irregularly.  Conidiophores poorly developed, usually unbranched. Conidiogenous cells to 30 µm long and 3-3.5 µm diam., rarely proliferating or with 1-2 annellations. Conidia 100-190 x 12-15 µm, 7-  to 12-septate, narrowly fusiform, slightly to strongly curved, pale brown with the end cells almost hyaline, tapering gradually to the obtuse apex and truncate base.
Teleomorph: ascostromata perithecial, 500-800 µm diam., oblate to oblate-spherical, scattered or in small clusters of 2-5, initially immersed within the blackened host epidermis but becoming erumpent and often surrounded by triangular radiating bark fissures, the ostiolar region central, papillate, 100-200 µm tall. Ascostromatal wall 50-80 µm thick laterally, thinner above and around the ostiolar region, composed of outer layers of elongate to angular dark brown cells and an inner layer of flattened hyaline cells. Interascal tissue of narrow pseudoparaphyses, 1.5-2 µm diam., septate, branched and anastomosed, developing within a gelatinous matrix.  Asci 220-250 x 38-42 µm, clavate, very thick-walled, fissitunicate, with a short tapering base and a rounded apex with a conspicuous ocular chamber, not staining blue in iodine, 8-spored. Ascospores arranged biseriately, 40-56 x 14-20 µm, fusiform to fusiform-ellipsoidal, the ends obtuse to rounded, with a strongly constricted median to slightly submedian primary septum and two secondary septa (also constricted) dividing the primary cells ± equally, very thick-walled, at first hyaline and smooth-walled, becoming mid brown at maturity, surrounded by a very conspicuous gelatinous sheath 2-5 µm thick within the ascus, expanding greatly after discharge.