Plagiostoma apiculatum  

Anamorph: referred to Diplodina microsperma (Johnst.) B. Sutton by Meijia et al. (2011), though that name has also been applied to P. convexum.
Teleomorph: stroma absent. Ascomata perithecia, 350-500 µm diam. and 250-350 µm high, globose to oblate, immersed in bark tissues, solitary, scattered, slightly raising the substratum surface, the ostiole slightly protruding through a sometimes radiating crack, and surrounded by a narrow black ring, the included area usually becoming completely black. Neck 150-250 µm tall, central to eccentric, straight to oblique, usually surrounded by an expanded discoid plug of melanized tissue to ca 300 µm diam. Interascal tissue not seen. Asci 61-85 x 12.5-16.5 µm, ellipsoidal-clavate, evanescent at the base and thus usually appearing ± sessile, thin-walled, not fissitunicate, the apex rounded with a well-developed refractive subapical ring ca 3 µm diam. and 1 µm thick, not staining in iodine, 8-spored. Ascospores arranged biseriately, 15.5-17.5 (-18.5) x 4.5-6 µm, cylindric-ellipsoidal, often slightly curved, usually with one end rounded to obtuse and the other obtuse, slightly constricted at the usually ± median septum, rather thin-walled, hyaline, smooth, without a gelatinous sheath or appendages.