Leptosphaeria acuta  

Anamorph: Phoma piskorzii. Conidiomata aggregated into small to large clusters but mostly not coalescing, ± superficial, 80-100 µm diam., irregular in form and sometimes slightly elongate, black, smooth to irregularly roughened, the ostiole not conspicuous. Conidiomatal wall made of dark brown thin-walled angular cells to 9 µm diam., darker towards the apex. Conidiophores absent. Conidiogenous cells formed in a palisade lining the inner wall, 3.5-4.5 µm diam., globose to doliiform, proliferating percurrently but periclinal thickening and collarette not evident. Conidia 4.5-5.5 x 1.8-2.2 µm, bacilliform, sometimes slightly curved, aseptate, hyaline, thin-walled, often with guttules at each end, without an epispore or gelatinous sheath.
Teleomorph: Ascomata perithecial, in large clusters but rarely coalescing, 300-450 µm diam., ± superficial, the apex often strongly papillate and the base ± flat, sometimes surrounded by a narrow collar of stromatic tissue, black, smooth and glossy. Interascal tissue composed of cellular pseudoparaphyses 2.5-3 µm diam., branched and anastomosing. Asci 140-160 x 10-12.5 µm, cylindrical, with a long tapering base, the apex rounded, thick-walled and fissitunicate with a distinct ocular chamber, 8-spored. Ascospores arranged biseriately, 45-58 x 7-8.5 µm, fusiform, the apex ± obtuse and the base acute, usually 9- or 10-septate, constricted at the septa especially in the mid portion, golden brown, thin-walled, smooth, without an epispore, gelatinous sheath or appendages.