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Family: MycosphaerellaceaeGenus: Polythrincium
Anamorph: colonies punctiform or effuse, dark brown to black. Mycelium immersed, setae and appressoria not present. Conidiomata absent. Conidiophores to ca 100 x 6-9 µm, forming in compact clusters from an immersed basal stroma, well differentiated from sterile hyphae, unbranched or branched at the base, the upper part often curved and thickened on the side away from the curvature, smooth, mid brown. Conidiogenous cells not clearly distinguished from conidiophores, proliferating sympodially, undulate and cicatrized, the scars pigmented, flat and formed only on one side of the conidiogenous cell. Conidia 17-24 x 13-24 µm, clavate to cuneiform, hyaline to pale brown, smooth or verruculose, 1-septate, not formed in chains, without a gelatinous sheath or appendages. A microconidial (spermatial) morph is also reported, with conidiomata formed in autumn from the conidial stromata, producing minute cylindrical to ovoid hyaline spores ca 5 x 1.5 µm in size.
Teleomorph: ascomata forming after overwintering in fallen leaves from the same stromata as the conidiophores, perithecial, globose to pyriform. Interascal tissue absent. Asci 50-55 x 20-30 µm, clavate, fissitunicate, 8-spored. Ascospores 20-26 x 8-9 µm, hyaline to pale yellowish or pale brown, clavate to fusiform-ellipsoidal, straight or inaequilateral, 1-septate, the upper cell slightly longer and wider than the lower one, thin-walled, smooth, without a gelatinous sheath or appendages.