Mellitosporium hysterinum  

Anamorph: not known.
Teleomorph: stromata absent. Ascomata apothecia, erumpent through the substratum and splitting open to reveal the hymenium; (700-) 900-1400 x 400-600 µm when fully mature, discoid and widely elliptical, the long axis usually parallel to the wood grain, black and leathery in appearance with an irregular raised margin, grey laterally where the host tissues cover the fungal cells. Hymenium exposed permanently once the ascoma is mature, 60-80 µm thick,  blueing in KOH/Lugol's iodine. Lower wall strongly melanized and occluded, to ca 15 µm thick, with a colourless to pale yellow subhymenial layer 7-10 µm thick. Lateral exciple dark brown, composed of a thin layer of dark brown thick-walled parallel agglutinated hyphae ca 1.5 µm diam. Lip cells apparently absent. Interascal tissue of rather thick-walled gelatinized unbranched paraphyses 1.5-2 µm diam., enlarged and sometimes branching at the apex and with a brown epithecial layer. Asci 62-78 x 13-16.5 (-19) µm, cylindrical to cylindric-clavate, short-stalked, the apex rounded, rather thick-walled, thickened at the apex with a tholus 5-8 µm thick and with a narrow ocular chamber occasionally visible, not reacting in iodine but with a gelatinous outer coat that blues in KOH/Lugol's iodine, 8-spored. Ascospores (17-) 17.5-20 (-22) x 8-9.5 (-10) µm, ellipsoidal to cylindric-ellipsoidal, the ends rounded, colourless, with 5 (-7) transverse septa and most cells eventually divided longitudinally, the individual cells sometimes bulging, the central septum sometimes more constricted, gelatinous sheath not seen.