Polythrincium Kunze, Mykologische Hefte (Leipzig) 1: 13 (1817).
Index Fungorum number: IF 9515; Facesoffungi number: FoF 08549, 1 morphological species (Species Fungorum 2021), 1 species with molecular data.
Colonies punctiform or effuse, olivaceous brown. Sexual morph: Cymadothea trifolii. Asexual morph: Mycelium immersed. Stroma pseudoparenchymatous, brown to black. Setae and hyphopodia absent. Conidiophores macronematous, mononematous, caespitose, unbranched or with several branches arising at one point, the upper part curved and often thickened on the side away from the curvature, undulate, often torsive, mid pale brown, smooth. Conidiogenous cells polyblastic, integrated, terminal, sympodial, cylindrical, undulate, cicatrized; scars large, flat, unilateral. Conidia solitary, acropleurogenous, simple, cuneiform or pyriform, hyaline to pale brown, smooth or verruculose, uniseptate (adapted from Videira et al. 2017).
Type species: Polythrincium trifolii Kunze
Notes: Polythrincium is characterised by pseudoparenchymatous, brown to black stroma, polyblastic conidiogenous cells, cuneiform or pyriform conidia. Simon et al. (2009) confirmed the phylogenetic link between the sexual morph Cymadothea trifolii and Polythrincium trifolii by extracting DNA directly from leaf spot caused by the pathogen on Trifolium repens found in Germany (CBS H20110). The phylogenetic placement of Polythrincium is confirmed in Mycosphaerellaceae based on DNA sequence data. Molecular markers available for Polythrincium are LSU and an unverified ITS sequence.