Eutypa spinosa  

Anamorph: conidiomata absent. Conidiophores in large irregular clusters or in a palisade on the stroma surface, short, dark brown, frequently branched with clusters of conidiogenous cells or with the conidiogenous cells simply the terminal cell of the conidiophore. Conidiogenous cells 12-21 x 2.5-3 (-4) µm, hyaline to pale brown, irregular in form but ± cylindrical, proliferating sympodially and usually with multiple denticles. Conidia 11-18 x 2-2.5 (-3) µm, irregularly falcate, the ends somewhat attentuated and ± acute, hyaline, aseptate, smooth- and thin-walled.
Teleomorph: stroma effuse, in wood or bark, strongly lifting and disrupting the substratum surface in broad plates, the surface black, delimited by a black zone line visible within the wood, in young material covered in tomentose brown hyphae. Ostioles separately emergent, very prominent, 200-400 µm diam. and 2-3 mm in height, ± cylindrical, ± furrowed or deeply split. Ascomata perithecia, 600-700 µm diam. and to 1.1 mm tall, in a single layer, close together and distorted due to contact with other perithecia, spherical to ovoid, with a long neck. Interascal tissue of very thin-walled tapering paraphyses, often deliquescent at maturity. Asci 25-35 x 5-6 µm (spore-bearing part, with a long tapering stalk 35-75 µm in length, with a small apical ring that blues in iodine, 8-spored. Ascospores (5.5-) 6-7.5 (-9) x (1.5-) 1.8-2.2 µm, allantoid, aseptate, pale yellow, thin- and smooth-walled, without an epispore or gelatinous sheath.